Anatomy

Animal Cell Anatomy

The cell is the basic unit of life. All organisms are made up of cells (or in some cases, a single cell). Most cells are very small; most are invisible without using a microscope. Cells are covered by a cell membrane and come in many different shapes. The contents of a cell are called the protoplasm.

The following is a glossary of animal cell terms:
cell membrane - the thin layer of protein and fat that surrounds the cell. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.centrosome - (also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. The centriole is the dense center of the centrosome.cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located.Golgi body - (also called the Golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. It produces the membranes that surround the lysosomes. The Golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell.lysosome - (also called cell vesicles) round organelles surrounded by a membrane and containing digestive enzymes. This is where the digestion of cell nutrients takes place.mitochondrion - spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell.nuclear membrane - the membrane that surrounds the nucleus.nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced. Some cells have more than one nucleolus.nucleus - spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane.ribosome - small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis.rough endoplasmic reticulum - (rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transports materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane).smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transports materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body, lysosomes, and membranes.vacuole - fluid-filled, membrane-surrounded cavities inside a cell. The vacuole fills with food being digested and waste material that is on its way out of the cell.
Related Pages:
Animal Cell Anatomy Label Me! PrintoutLabel the animal cell diagram using the separate page with a glossary of animal cell terms. Answers
Animal Cell Anatomy Label Me! PrintoutLabel the animal cell diagram using the attached glossary of animal cell terms.Answers
3-D Jello Animal Cell ModelMake your own giant animal cell model using Jello and candies (and then eat it).

Mitosis, Animal CellLabel the animal cell mitosis diagram.Answers
Neuron Anatomy: Label the CellLabel the axon, dendrites, cell body, nucleus, Schwann's cells, and nodes of Ranvier.Answers
Plant CellLabel the plant cell diagram using the glossary of plant cell terms.Answers











Label Amoeba DiagramUsing the definitions listed below, label the amoeba.


cell membrane - the thin layer of protein and fat that surrounds the amoeba; it allows some substances to pass into the cell, and blocks other substances.contractile vacuole - a cavity within the amoeba that excretes excess water and waste; the waste is brought to the cell membrane and is then eliminated from the amoeba.cytoplasm - a jelly-like material that fills most of the cell; the organelles (like the nucleus) are surrounded by cytoplasm.food vacuole - a cavity within the amoeba in which food is digested (broken down in order to be absorbed by the amoeba).food being engulfed by pseudopods - the amoeba "eats" by surrounding bits of food with pseudopods that form around the food; the amoeba then incorporates the food into the cell, forming a food vacuole.nucleus - the major organelle of the amoeba, located centrally; it controls reproduction (it contains the chromosomes) and many other important functions (including eating and growth).pseudopods - temporary "feet" that the amoeba uses to move around and to engulf food.




Answers - Bacterium Cell Label Me! PrintoutLabel the bacterium cell diagram below using the bacterium cell glossary below.



The cell is the basic unit of life. The following is a glossary of Bacterium cell terms.
basal body - A structure that anchors the base of the flagellum and allows it to rotate.capsule - A layer on the outside of the cell wall. Most but not all bacteria have a capsule.cell wall - A thin membrane located outside the plasma membrane and within the capsule.DNA - The genetic material of the bacterium; it is located within the cytoplasm.cytoplasm - The jellylike material inside the plasma membrane in which the genetic material and ribosomes are located.
flagellum - A long whip-like structure used for locomotion (movement). Some bacteria have more than one flagellum.pili - (singular is pilus) Hair-like projections that allow bacterial cells to stick to surfaces and transfer DNA to one another.plasma membrane - A permeable membrane located within the cell wall. It serves many functions for the cell, including energy generation and transport of chemicals .ribosome - Small organelles composed of RNA-rich granules that are sites of protein synthesis. The ribosomes are located within the cytoplasm.


Label the Chicken Egg (#1)Label the cross section of a newly-laid chicken egg.


air cell - an empty space located at the large end of the egg; it is between the inner and outer shell membranes. chalaza - a spiral, rope-like strand that anchors the yolk in the thick egg white. There are two chalazae anchoring each yolk; one on the top and one on the bottom. (The plural of chalaza is chalazae.)germinal disc - a small, circular, white spot (2-3 mm across) on the surface of the yolk; it is where the sperm enters the egg. The nucleus of the egg is in the blastodisc.shell - the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg. The shell is made of calcium carbonate.albumin - the egg white.yolk - the yellow, inner part of the egg where the embryo will form. The yolk contains the food that will nourish the embryo as it grows.




Label the Chick Embryo (72 hours)Label the cross section of a 72-hour old chicken embryo.


allantois - a large sack that holds some of the embryo's waste. It is located near the far end (the posterior) of the embryo, close to the leg buds. brain - the developing brain takes up much of the head area (at the anterior) of the embryo. eye - at this point in development, the eye consists of an eye cup and lens, and is located near the brain. heart - the developing heart is above (anterior to) the wing buds and below (posterior to) the head. leg bud - the beginning of the development of the of the legs are small bumps of tissue located just above (anterior to) the tail bud. spinal cord - the developing spinal cord runs through the length of the embryo, from the brain to the tail. tail bud - the beginning of the development of the of the tail is located at the far end (the posterior) of the embryo. wing bud - the beginning of the development of the wings are small bumps of tissue located in the mid-section of the embryo.
Label the Chicken Egg (10 days old) #1Label a 10-day old chicken embryo in egg.


air cell - a space at the large end of the egg, between the inner and outer shell membranes. albumin - the egg white. It provides protein and water for the embryo and protects it from microorganisms. eggshell - the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg. It is made of calcium carbonate. embryo - the developing chick inside the egg. eye - large and prominent on the head. leg - one of the lower limbs of the chick. tail - located at the far end (the posterior) of the embryo. wing - one of the upper limbs of the chick. yolk - the yellow part of the egg; it contains nourishment (food) for the embryo.



Animal Cell Mitosis.
Mitosis is the duplication and division of a eukaryotic cell's nucleus and nuclear material (DNA). The stages of mitosis are: [interphase (the cell when not undergoing mitosis, but the DNA is replicated)], prophase, metaphase, anaphase, and telophase.

Terms to Use:
Anaphase - the phase of mitosis in which the chromosomes begin to separate.Centrioles - paired cylindrical organelles, arranged at right angles to each other, located at the center of a microtubule.Centromeres - a centromere is the constricted region of a nuclear chromosome - microfibers attach to the centromere during mitosis.Chromosomes - structures in the nucleus that contain DNA molecules that contain the genes.
Interphase - the phase of a cell's life cycle in which DNA is replicated.Microtubules - tiny filaments (about 25 nanometers in diameter) that are active in mitosis.Metaphase - the phase of mitosis in which the chromosomes line up at the equator (the central plane) of the cell.Prophase - the phase of mitosis in which the duplicated chromosomes condense, the nuclear envelope dissolves, and centrioles divide and move to opposite ends of the cell.Telophase - the last phase of mitosis, when the chromosomes migrate to opposite ends of the cell, two new nuclear envelopes form, and the chromosomes uncoil.


Answers Animal Cell MitosisLabel Me! PrintoutLabel the mitosis diagram using the terms below.
Mitosis is the duplication and division of a eukaryotic cell's nucleus and nuclear material (DNA). The stages of mitosis are: [interphase (the cell when not undergoing mitosis, but the DNA is replicated)], prophase, metaphase, anaphase, and telophase.

Terms to Use:
Anaphase - the phase of mitosis in which the chromosomes begin to separate.Centrioles - paired cylindrical organelles, arranged at right angles to each other, located at the center of a microtubule.Centromeres - a centromere is the constricted region of a nuclear chromosome - microfibers attach to the centromere during mitosis.Chromosomes - structures in the nucleus that contain DNA molecules that contain the genes.
Interphase - the phase of a cell's life cycle in which DNA is replicated.Microtubules - tiny filaments (about 25 nanometers in diameter) that are active in mitosis.Metaphase - the phase of mitosis in which the chromosomes line up at the equator (the central plane) of the cell.Prophase - the phase of mitosis in which the duplicated chromosomes condense, the nuclear envelope dissolves, and centrioles divide and move to opposite ends of the cell.Telophase - the last phase of mitosis, when the chromosomes migrate to opposite ends of the cell, two new nuclear envelopes form, and the chromosomes uncoil.

Read the definitions, then label the neuron diagram below.

axon - the long extension of a neuron that carries nerve impulses away from the body of the cell.
axon terminals - the hair-like ends of the axon
cell body - the cell body of the neuron; it contains the nucleus (also called the soma)
dendrites - the branching structure of a neuron that receives messages (attached to the cell body)
myelin sheath - the fatty substance that surrounds and protects some nerve fibers
node of Ranvier - one of the many gaps in the myelin sheath - this is where the action potential occurs during saltatory conduction along the axon
nucleus - the organelle in the cell body of the neuron that contains the genetic material of the cell
Schwann's cells - cells that produce myelin - they are located within the myelin sheath.





Plant Cell Anatomy

The cell is the basic unit of life. Plant cells (unlike animal cells) are surrounded by a thick, rigid cell wall.

The following is a glossary of plant cell anatomy terms.
amyloplast - an organelle in some plant cells that stores starch. Amyloplasts are found in starchy plants like tubers and fruits.ATP - ATP is short for adenosine triphosphate; it is a high-energy molecule used for energy storage by organisms. In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts.cell membrane - the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.cell wall - a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.centrosome - (also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell.chlorophyll - chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green.chloroplast - an elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts.christae - (singular crista) the multiply-folded inner membrane of a cell's mitochondrion that are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated).cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located.Golgi body - (also called the golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell.granum - (plural grana) A stack of thylakoid disks within the chloroplast is called a granum.mitochondrion - spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell.nuclear membrane - the membrane that surrounds the nucleus.nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced.nucleus - spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membranephotosynthesis - a process in which plants convert sunlight, water, and carbon dioxide into food energy (sugars and starches), oxygen and water. Chlorophyll or closely-related pigments (substances that color the plant) are essential to the photosynthetic process.ribosome - small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis.rough endoplasmic reticulum - (rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transport materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane).smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transport materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body and membranesstroma - part of the chloroplasts in plant cells, located within the inner membrane of chloroplasts, between the grana.thylakoid disk - thylakoid disks are disk-shaped membrane structures in chloroplasts that contain chlorophyll. Chloroplasts are made up of stacks of thylakoid disks; a stack of thylakoid disks is called a granum. Photosynthesis (the production of ATP molecules from sunlight) takes place on thylakoid disks.vacuole - a large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell.


Read the definitions, then label the strata (layers) of the tropical rainforest diagram below.

canopy - the upper parts of most of the trees (about 65 to 130 feet or 20 to 40 m tall). This leafy environment is full of life: insects, arachnids, many birds, some mammals, etc.
emergents - the tops of the tallest trees, which are much higher than the average trees (the canopy).
forest floor - the ground - it is teeming with animal life, especially insects and arachnids, plus large animals (like anacondas and jaguars).
understory - a dark, cool environment that is under the leaves but over the ground. Most of the understory of a rainforest has so little light that plant growth is limited. There are short, leafy, mostly non-flowering shrubs, small trees, ferns, and vines (lianas) that have adapted to filtered light and poor soil.





The Brain
Human Anatomy

Introduction
Structureand Function
Brain Cells
Spinal Cord
Animal BrainComparisons
Glossary
Classroom Activitiesand Links

Introduction to the Brain
THE FUNCTIONS OF THE BRAIN The human brain is a complex organ that allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives information, analyzes information, and stores information (our memories).
The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body.
SIZE OF THE HUMAN BRAIN The average human brain weighs about 3 pounds (1300-1400 g).
At birth, the human brain weighs less than a pound (0.78-0.88 pounds or 350-400 g). As a child grows, the number of cell remains relatively stable, but the cells grow in size and the number of connections increases. The human brain reaches its full size at about 6 years of age.
COMPOSITION OF THE BRAIN The brain consists of gray matter (40%) and white matter (60%) contained within the skull. Brain cells include neurons and glial cells.
The brain has three main parts: the cerebrum, the cerebellum, and the brain stem (medulla). NOURISHMENT OF THE BRAIN Although the brain is only 2% of the body's weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. Blood vessels (arteries, capillaries, and veins) supply the brain with oxygen and nourishment, and take away wastes. If brain cells do not get oxygen for 3 to 5 minutes, they begin to die.
Cerebrospinal fluid (CSF) surrounds the brain.
THE NERVOUS SYSTEM The brain and spinal cord make up the central nervous system (CNS). The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body.
The nerves that connect the CNS to the rest of the body are called the peripheral nervous system.
The autonomic nervous system controls our life support systems that we don't consciously control, like breathing, digesting food, blood circulation, etc. PROTECTION The cells of the nervous system are quite fragile and need extensive protection from being crushed, being infected by disease organisms, and other harm. The brain and spinal cord are covered by a tough, translucent membrane, called the dura matter. Cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts.
The cranium (the top of the skull) surrounds and protects the brain. The spinal cord is surrounded by vertebrae (hollow spinal bones). Also, some muscles serve to pad and support the spine.
More subtly, the blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain.
STRUCTURE AND FUNCTION OF THE HUMAN BRAIN
The brain has three main parts, the cerebrum, the cerebellum, and the brain stem. The brain is divided into regions that control specific functions.
THE CEREBRUM:Frontal Lobe
Behavior
Abstract thought processes
Problem solving
Attention
Creative thought
Some emotion
Intellect
Reflection
Judgment
Initiative
Inhibition
Coordination of movements
Generalized and mass movements
Some eye movements
Sense of smell
Muscle movements
Skilled movements
Some motor skills
Physical reaction
Libido (sexual urges)
Occipital Lobe
Vision
Reading
Parietal Lobe
Sense of touch (tactile sensation)
Appreciation of form through touch (stereognosis)
Response to internal stimuli (proprioception)
Sensory combination and comprehension
Some language and reading functions
Some visual functions
Temporal Lobe
Auditory memories
Some hearing
Visual memories
Some vision pathways
Other memory
Music
Fear
Some language
Some speech
Some behavior and emotions
Sense of identity
Right Hemisphere (the representational hemisphere)
The right hemisphere controls the left side of the body
Temporal and spatial relationships
Analyzing nonverbal information
Communicating emotion
Left Hemisphere (the categorical hemisphere)
The left hemisphere controls the right side of the body
Produce and understand language
Corpus Callosum
Communication between the left and right side of the brain
THE CEREBELLUM
Balance
Posture
Cardiac, respiratory, and vasomotor centers
THE BRAIN STEM
Motor and sensory pathway to body and face
Vital centers: cardiac, respiratory, vasomotor
Hypothalamus
Moods and motivation
Sexual maturation
Temperature regulation
Hormonal body processes
Optic Chiasm
Vision and the optic nerve
Pituitary Gland
Hormonal body processes
Physical maturation
Growth (height and form)
Sexual maturation
Sexual functioning
Spinal Cord
Conduit and source of sensation and movement
Pineal Body
Unknown
Ventricles and Cerebral Aqueduct
Contains the cerebrospinal fluid that bathes the brain and spinal cord

The Spinal Cord


The spinal cord is a bundle of nerves that connects the brain to other parts of the body. It is protected by a series of doughnut-shaped bones called vertebrae, which surround the spinal cord.
The human spinal cord is about 43-45 cm long and approximately as wide as a human finger. There are 13,500,000 neurons that transmit electro-chemical signals in the spinal cord. The cord weighs approximately 35 grams. The vertebral column (bones) that supports it is about 70 cm long and has 31 segments and 31 pairs of spinal nerves.
Spinal Cord Vertebrae
7 cervical (neck) segments
12 thoracic segments
5 lumbar segments
5 sacral segments
4 fused coccygeal segment
ANIMAL BRAIN COMPARISONS

BRAINS OF VARIOUS ANIMALS
ANIMAL
BRAIN WEIGHT (G)
BODY WEIGHT
% OF BODY WEIGHT
NUMBER OF NEURONS
SPERM WHALE
7800 g
15 tons=30,000 pounds= 13500 kg
0.06 %

ELEPHANT
6000



BOTTLE-NOSED DOLPHIN
1500 g
500 kg
0.3 %

HUMAN ADULT
1300-1400
150 pounds= 68 kg=68000 g
2 %
100 Billion
HORSE
532



CHIMPANZEE
420



HUMAN BABY
350 - 400



DOG (BEAGLE)
72
9 to 18 kg
0.5 %

CAT
30



SQUIRREL
22



ALLIGATOR
8.4
250 kg
0.003 %

OWL
2.2



RAT
2
400 gm
0.5 %

TURTLE
0.3



VIPER
0.1



GREEN LIZARD
0.08




GLOSSORY

A
acetylcholine - a neurotransmitter that carries nerve impulses across a synapse from one neuron to another or from a neuron to a muscle.
afferent - carrying something (like a nerve impulse) toward the central part.
amygdala - a part of the brain (and part of the limbic system) that is used in emotion.
anterior - towards the front.
anterior commissure - a small fiber that connects the right and left cerebral hemispheres of the brain.
arachnoid - one of the three membranes that protects the brain and spinal cord. The space between the arachnoid and the pia (another membrane) is filled with cerebrospinal fluid, protecting the brain from physical blows and providing the brain with nutrients.
association cortex - any part of the cortex in which information is analyzed, processed, or stored.
astroglia or astrocyte - a type of glial cell that supports neurons.
autonomic nervous system - controls our life support systems that we don't consciously control, like breathing, digesting food, blood circulation, etc.
axon - the long extension of a neuron that carries nerve impulses away from the body of the cell.
axodendritic synapse - a synapse formed by contact between a presynaptic axon and a postsynaptic dendrite.
B
basal ganglia - groups of hundreds of thousands of neurons at the base of the cerebrum and in the upper brainstem; they help control well-learned movements (like walking) and sensation.
blood-brain barrier - the blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain.
brain - the organ in the body that is responsible for thought, memory, sensory interpretation, movement, and other vital functions.
brainstem or brain stem - the base of the brain. This part of the brain connects the brain's cerebrum to the spinal cord. The brain stem controls many automatic and motor functions. The brain stem is composed of the medulla oblongata, the pons, the midbrain, and the reticular formation.
C
cauda equina - (meaning "horse's tail" in Latin) the bundle of nerve roots below the end of the spinal cord.
caudal - toward the tail.
cell body (soma) - the cell body of the neuron; it contains the nucleus.
central nervous system (CNS) - the brain and spinal cord
central sulcus - a large groove in the brain that separates the frontal and parietal lobes
cerebellum - the part of the brain below the back of the cerebrum. It regulates balance, posture, movement, and muscle coordination.
cerebral aqueduct - the part of the ventricular system that connects the third and fourth ventricles
cerebral cortex - the outer layer of the cerebrum, composed of six cell layers of deeply folded and ridged gray matter.
cerebral hemisphere - one side of the cerebrum, the left or right side of the cerebrum.
cerebrospinal fluid (CSF) - a clear, watery liquid that surrounds and protects the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts. This fluid circulates through the brain and the spinal canal.
cerebrum - the largest and most complex portion of the brain. It controls thought, learning, and many other complex activities. It is divided into the left and right cerebral hemispheres that are joined by the corpus callosum, which communicates between the two hemispheres. The right side of the brain controls the left side of the body, and vice versa. Each cerebral hemisphere is divided into four lobes: the frontal lobe (responsible for reasoning, emotions, judgment, and voluntary movement); the temporal lobe (contains centers of hearing, smells, and memory); the parietal lobe (responsible for touch and spoken language ability), and the occipital lobe (responsible for centers of vision and reading ability).
choroid plexus - vascular structures within the ventricular system that produce cerebrospinal fluid.
corpus callosum- a large bundle of nerve fibers that connect the two cerebral hemispheres.
cortex - the outer layer of the cerebrum, composed of six cell layers of deeply folded and ridged gray matter.
cranial nerves - 12 pairs of nerves that carry information to and from sense organs, muscles and internal organs. The cranial nerves include: olfactory nerve (smell), optic nerve (sight), oculomotor nerve (eye movement, dilation of pupil), trochlear nerve (eye movement), trigeminal nerve (sensation from the head and chewing muscles), abduccens nerve,
cranium - the top of the skull; it protects the brain. The cranium and the facial bones make up the skull.
CSF (cerebrospinal fluid) - a clear, watery liquid that surrounds the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts.
D
dendrites - the branching structure of a neuron that receives messages.
dorsal - on the back or upper surface.
dorsal root - a bundle of nerve fibers that bring information to the spinal cord.
dura matter - a tough, translucent membrane that protects the brain and spinal cord.
E
efferent - carrying something (like a nerve impulse) away from the central part.
electroencephalogram (EEG) - a graphical record of the electrical activity of the brain. Electrodes are placed on the scalp to obtain this information.
"Eloquent" brain - The parts of the brain that control the senses, speech, and motor functions.
endocrine gland - ductless glands that secrete endocrine hormones; examples include the pituitary and thyroid.
F
fornix - a pathway that connects the hippocampus and the mamillary bodies.
frontal lobe - the top, front regions of each of the cerebral hemispheres. They are used for reasoning, emotions, judgment, and voluntary movement.
G
ganglion - a group of neuron bodies (not in the brain or spinal cord)
glial cells - nerve cells that form a supporting network for the neurons in the brain. The word "glia" comes from the Greek word for glue.
gray matter - central nervous tissue that is relatively dark in color (in contrast to white matter) because of the relatively high proportion of nerve cell nuclei present
gyrus - (plural is gyri) - these are high areas on the brain that are separated by fissures.
H
hormones - biochemical substances that are produced by specific cells, tissues, or glands in the body. Hormones regulate the growth and functions of cells and tissues in the body. A examples of a hormone is insulin, which is secreted by the pancreas. Hormones were first discovered by the British scientists William Bayliss and Ernest Starling in 1902.
hypothalamus - a region in the upper part of the brainstem that acts as a relay to the pituitary gland - it controls body temperature, circadian cycles, sleep, moods, hormonal body processes, hunger, and thirst. The hypothalamus is part of the limbic system and works with the pituitary gland.
I
inferior colliculus - a structure in the midbrain that is used in hearing
L
lateral - to the side
left hemisphere - the left half of the cerebrum - it is the center for speech and language. In some left-handed people, however, the right hemisphere controls speech.
limbic system - the interconnected areas of the brain that are used in emotions and some other behaviors.
M
medulla oblongata - the lowest section of the brainstem (at the top end of the spinal cord); it controls automatic functions including heartbeat, breathing, swallowing, etc.
meninges - a series of three protective membranes (the dura matter, the arachnoid, and the pia) that cover the brain and the spinal cord.
microglia - a type of glial cell in the CNS
midbrain (mesencephalon) - a middle area of the brainstem that contains many important nerves (including the origins of the third and fourth cranial nerves which control eye movement and eyelid opening).
motor cortex - the part of both frontal lobes of the brain that controls voluntary muscle movements.
motoneurons (multipolar neurons) - neurons responsible for movement - the cell bodies of these neurons are located within the brain or spinal cord and the axons are located in muscle fibers
myelin - a fatty substance that covers axons.
myelin sheath - a fatty substance that surrounds and protects some nerve fibers.
N
neuroglia - connective or supporting tissues of the nervous system.
neuron - a nerve cell. Neurons have specialized projections (dendrites and axons) and communicate with each other via an electrochemical process. The word "neuron" was coined by the German scientist Heinrich Wilhelm Gottfried von Waldeyer-Hartz in 1891 (he also coined the term "chromosome").
neuroscience - the study of the brain and the nervous system.
neurotransmitters - chemicals that transmit nerve impulses between neurons. Some neurotransmitters include acetylcholine, dopamine, endorphin, epinephrine, serotonin, and histamine.
node of Ranvier - one of the many gaps in the myelin sheath - this is where the action potential occurs during saltatory conduction along the axon
nucleus - the organelle in the cell body of the neuron (and all cells) that contains the genetic material of the cell (DNA in chromosomes). It is where DNA (deoxyribonucleic acid) replicates itself, and where RNA (ribonucleic acid) is made.
O
occipital lobe - the region at the back of each cerebral hemisphere that contains the centers of vision and reading ability.
optic chiasm - controls vision and the optic nerve. It is the area in the front of the brain where the optic nerves cross one another.
P
paleoneuroloy - the study of fossils brains (from brain casts, called endocasts).
parietal lobe - the middle lobe of each cerebral hemisphere between the frontal and occipital lobes; it contains important sensory centers.
peripheral nervous system - the part of the nervous system that includes the cranial nerves and the spinal nerves.
pia - the innermost layer of the meninges. It is adjacent to the surface of the brain and the arachnoid.
pineal body - a pinecone-shaped gland-like structure located in the brain. It produces melanin and influences the onset of puberty.
pituitary gland - a gland attached to the base of the brain that secretes hormones.
plexus - a network of nerves or veins
pons - the part of the brainstem that joins the hemispheres of the cerebellum and connects the cerebrum with the cerebellum. It is where the four pairs of cranial nerves originalte: the fifth (facial sensation); the sixth (eye movement); the seventh (taste, facial expression, eyelid closure); and the eighth (hearing and balance)
posterior - towards the back
posterior fossa - the part of the skull that contains the brain stem and the cerebellum.
proprioception - the response to internal stimuli.
pseudounipolar cells - a type of neuron that has two axons (instead of one axon and one dendrite). One axon is oriented towards the spinal cord, the other axon is oriented toward either skin or muscle.
R
reticular formation - a network of nerve cells in the brainstem that are involved in maintaining sleep or wakefulness.
right hemisphere - the right half of the cerebrum - it processes visual information.
S
Schwann's cells - cells that produce myelin
sensory cortex - any part of the brain that receives messages from a sense organ (like the eyes, nose, tongue, or ears) or messages of touch and temperature from anywhere in the body.
sensory neuron (bipolar neuron) - an afferent nerve cell that carries sensory information (like sound, touch, taste, smell, or sight) to the central nervous system.
skull - the bones that comprise the head.
soma (cell body) - the cell body of the neuron; it contains the nucleus.
somatosensory cortex - an area of the sensory cortex in the parietal lobes that receives messages of touch, temperature, and certain other bodily sensations.
spinal cord - a thick bundle of nerve fibers that runs from the base of the brain to the hip area, running through the spine (vertebrae).
stereognosis - the appreciation of form through touch
sulcus (plural sulci) - a long groove on the surface of the brain
suprachiasmatic nucleus - the area of the hypothalamus that controls circadian rhythms (day and night cycles and the biological clock) and reproduction cycles.
synapse - a structure where an impulse passes from one neuron to another across a gap. The word "synapse" was coined by Sir Charles Scott Sherrington in 1897.
T
tactile sensation - the sense of touch
tectum - the dorsal (top) portion of the midbrain (mesencephalon)
tegmentum - ventral (bottom) part of the midbrain (mesencephalon)
temporal lobe - the region at the lower side of each cerebral hemisphere; contains centers of hearing and memory.
thalamus - a small structure at the top of the brainstem that serves as a relay center for sensory information, pain, attention, and alertness.
V
ventral - lower or underneath
ventricle - four small hollow spaces in the brain that are filled with cerebrospinal fluid - they contain the choroid plexus, which produce cerebrospinal fluid (CSF).
vertebra (plural vertebrae) - one of many small bones that make up the spine. The spinal cord runs through the vertebrae.
viscera - organs in the body
W
white matter - heavily myelinated central nervous tissue that is light in color (in contrast to gray matter) - it consists mostly of axons covered with the insulating lipid-protein sheath myelin.
Answers: Label the Brain Diagram
The Brain
Read the definitions below, then label the brain anatomy diagram.

Cerebellum - the part of the brain below the back of the cerebrum. It regulates balance, posture, movement, and muscle coordination.Corpus Callosum - a large bundle of nerve fibers that connect the left and right cerebral hemispheres. In the lateral section, it looks a bit like a "C" on its side.Frontal Lobe of the Cerebrum - the top, front regions of each of the cerebral hemispheres. They are used for reasoning, emotions, judgment, and voluntary movement.Medulla Oblongata - the lowest section of the brainstem (at the top end of the spinal cord); it controls automatic functions including heartbeat, breathing, etc.Occipital Lobe of the Cerebrum - the region at the back of each cerebral hemisphere that contains the centers of vision and reading ability (located at the back of the head).
Parietal Lobe of the Cerebrum - the middle lobe of each cerebral hemisphere between the frontal and occipital lobes; it contains important sensory centers (located at the upper rear of the head).Pituitary Gland - a gland attached to the base of the brain (located between the Pons and the Corpus Callosum) that secretes hormones.Pons - the part of the brainstem that joins the hemispheres of the cerebellum and connects the cerebrum with the cerebellum. It is located just above the Medulla Oblongata.Spinal Cord - a thick bundle of nerve fibers that runs from the base of the brain to the hip area, running through the spine (vertebrae).Temporal Lobe of the Cerebrum - the region at the lower side of each cerebral hemisphere; contains centers of hearing and memory (located at the sides of the head).



Human Digestive System
Human Anatomy
The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat, our body has to break the food down into smaller molecules that it can process; it also has to excrete waste.
Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body. The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals.
The Digestive Process:The start of the process - the mouth: The digestive process begins in the mouth. Food is partly broken down by the process of chewing and by the chemical action of salivary enzymes (these enzymes are produced by the salivary glands and break down starches into smaller molecules).
On the way to the stomach: the esophagus - After being chewed and swallowed, the food enters the esophagus. The esophagus is a long tube that runs from the mouth to the stomach. It uses rhythmic, wave-like muscle movements (called peristalsis) to force food from the throat into the stomach. This muscle movement gives us the ability to eat or drink even when we're upside-down.
In the stomach - The stomach is a large, sack-like organ that churns the food and bathes it in a very strong acid (gastric acid). Food in the stomach that is partly digested and mixed with stomach acids is called chyme.
In the small intestine - After being in the stomach, food enters the duodenum, the first part of the small intestine. It then enters the jejunum and then the ileum (the final part of the small intestine). In the small intestine, bile (produced in the liver and stored in the gall bladder), pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food.
In the large intestine - After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides, Lactobacillus acidophilus, Escherichia coli, and Klebsiella) in the large intestine help in the digestion process. The first part of the large intestine is called the cecum (the appendix is connected to the cecum). Food then travels upward in the ascending colon. The food travels across the abdomen in the transverse colon, goes back down the other side of the body in the descending colon, and then through the sigmoid colon.
The end of the process - Solid waste is then stored in the rectum until it is excreted via the anus.
Digestive System Glossary:anus - the opening at the end of the digestive system from which feces (waste) exits the body.appendix - a small sac located on the cecum.ascending colon - the part of the large intestine that run upwards; it is located after the cecum.bile - a digestive chemical that is produced in the liver, stored in the gall bladder, and secreted into the small intestine.cecum - the first part of the large intestine; the appendix is connected to the cecum.chyme - food in the stomach that is partly digested and mixed with stomach acids. Chyme goes on to the small intestine for further digestion.descending colon - the part of the large intestine that run downwards after the transverse colon and before the sigmoid colon.duodenum - the first part of the small intestine; it is C-shaped and runs from the stomach to the jejunum.epiglottis - the flap at the back of the tongue that keeps chewed food from going down the windpipe to the lungs. When you swallow, the epiglottis automatically closes. When you breathe, the epiglottis opens so that air can go in and out of the windpipe.esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle movements (called peristalsis) to force food from the throat into the stomach.gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile (a digestive chemical which is produced in the liver) into the small intestine.ileum - the last part of the small intestine before the large intestine begins.jejunum - the long, coiled mid-section of the small intestine; it is between the duodenum and the ileum.liver - a large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which breaks down fats) and some blood proteins.mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food).pancreas - an enzyme-producing gland located below the stomach and above the intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine.peristalsis - rhythmic muscle movements that force food in the esophagus from the throat into the stomach. Peristalsis is involuntary - you cannot control it. It is also what allows you to eat and drink while upside-down.rectum - the lower part of the large intestine, where feces are stored before they are excreted.salivary glands - glands located in the mouth that produce saliva. Saliva contains enzymes that break down carbohydrates (starch) into smaller molecules.sigmoid colon - the part of the large intestine between the descending colon and the rectum.stomach - a sack-like, muscular organ that is attached to the esophagus. Both chemical and mechanical digestion takes place in the stomach. When food enters the stomach, it is churned in a bath of acids and enzymes.transverse colon - the part of the large intestine that runs horizontally across the abdomen.

Digestive System (simple version)
Read the definitions, then label the digestive system anatomy diagram below.
anus - the opening at the end of the digestive system from which feces exit the body.appendix - a small sac located near the start of the large intestine.esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle movements (called peristalsis) to force food from the throat into the stomach.gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile (a digestive chemical which is produced in the liver) into the small intestine.large intestine - the long, wide tube that food goes through after it goes through the small intestine.liver - a large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which breaks down fats) and some blood proteins.mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food).pancreas - an enzyme-producing gland located below the stomach and above the intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine.rectum - the lower part of the large intestine, where feces are stored before they are excreted from the body.small intestine - the long, thin winding tube that food goes through after it leaves the stomach.stomach - a sack-like, muscular organ that is attached to the esophagus. When food enters the stomach, it is churned in an acid bath.


Ear Anatomy
Human Anatomy
Sound is collected by the pinna (the visible part of the ear) and directed through the outer ear canal. The sound makes the eardrum vibrate, which in turn causes a series of three tiny bones (the hammer, the anvil, and the stirrup) in the middle ear to vibrate. The vibration is transferred to the snail-shaped cochlea in the inner ear; the cochlea is lined with sensitive hairs which trigger the generation of nerve signals that are sent to the brain.
On average, people can hear sounds in the frequencies between 20 to 20,000 Hertz.

Definitions:
anvil - (also called the incus) a tiny bone that passes vibrations from the hammer to the stirrup.cochlea - a spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form.eardrum - (also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it.Eustachian tube - a tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. When you "pop" your ears as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear.hammer - (also called the malleus) a tiny bone that passes vibrations from the eardrum to the anvil.
nerves - these carry electro-chemical signals from the inner ear (the cochlea) to the brain.outer ear canal - the tube through which sound travels to the eardrum.pinna - (also called the auricle) the visible part of the outer ear. It collects sound and directs it into the outer ear canalsemicircular canals - three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance.stirrup - (also called the stapes) a tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to 0.33 cm long).




Label the Ear Anatomy Diagram
Human Anatomy
Sound is collected by the pinna (the visible part of the ear) and directed through the outer ear canal. The sound makes the eardrum vibrate, which in turn causes a series of three tiny bones (the hammer, the anvil, and the stirrup) in the middle ear to vibrate. The vibration is transferred to the snail-shaped cochlea in the inner ear; the cochlea is lined with sensitive hairs which trigger the generation of nerve signals that are sent to the brain.
Read the definitions below, then label the ear anatomy diagram.


anvil - (also called the incus) a tiny bone that passes vibrations from the hammer to the stirrup.cochlea - a spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form.eardrum - (also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it.Eustachian tube - a tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. When you "pop" your ears as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear.hammer - (also called the malleus) a tiny bone that passes vibrations from the eardrum to the anvil.
nerves - these carry electro-chemical signals from the inner ear (the cochlea) to the brain.outer ear canal - the tube through which sound travels to the eardrum.pinna - (also called the auricle) the visible part of the outer ear. It collects sound and directs it into the outer ear canalsemicircular canals - three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance.stirrup - (also called the stapes) a tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to 0.33 cm long).


Label the Eye Diagram

Read the definitions, then label the eye anatomy diagram below.
Cornea - the clear, dome-shaped tissue covering the front of the eye. Iris - the colored part of the eye - it controls the amount of light that enters the eye by changing the size of the pupil Lens - a crystalline structure located just behind the iris - it focuses light onto the retina Optic nerve - the nerve that transmits electrical impulses from the retina to the brain
Pupil - the opening in the center of the iris- it changes size as the amount of light changes (the more light, the smaller the hole) Retina - sensory tissue that lines the back of the eye. It contains millions of photoreceptors (rods and cones) that convert light rays into electrical impulses that are relayed to the brain via the optic nerve Vitreous - a thick, transparent liquid that fills the center of the eye - it is mostly water and gives the eye its form and shape (also called the vitreous humor)



Answers: Label the Eye Diagram #2
Human Anatomy
Read the definitions, then label the eye anatomy diagram below.
Cornea - the clear, dome-shaped tissue covering the front of the eye. Eyebrow - a patch of dense hair located above the eye. Eyelash - one of the many hairs on the edge of the eyelids. Eyelid - the flap of skin that can cover and protect the eye. Iris - the colored part of the eye - it controls the amount of light that enters the eye by changing the size of the pupil. Lens - a crystalline structure located just behind the iris - it focuses light onto the retina. Optic nerve - the nerve that transmits electrical impulses from the retina to the brain. Pupil - the opening in the center of the iris- it changes size as the amount of light changes (the more light, the smaller the hole). Retina - sensory tissue that lines the back of the eye. It contains millions of photoreceptors (rods and cones) that convert light rays into electrical impulses that are relayed to the brain via the optic nerve. Tear - clear, salty liquid that is produced by glands in the eyes. Vitreous - a thick, transparent liquid that fills the center of the eye - it is mostly water and gives the eye its form and shape (also called the vitreous humor).



Parts of The Face
More Anatomy Activities




Heart Interior Anatomy Diagram
The heart is a fist-sized, muscular organ that pumps blood through the body. Oxygen-poor blood enters the right atrium of the heart (via veins called the inferior vena cava and the superior vena cava). The blood is then pumped into the right ventricle and then through the pulmonary artery to the lungs, where the blood is enriched with oxygen (and loses carbon dioxide). The oxygen-rich (oxygenated) blood is then carried back to the left atrium of the heart via the pulmonary vein. The blood is then pumped to the left ventricle, then the blood is pumped through the aorta and to the rest of the body. This cycle is then repeated. Every day, the heart pumps about 2,000 gallons (7,600 liters) of blood, beating about 100,000 times.



Read the definitions, then label the label anatomy diagram below.



aorta - the biggest and longest artery (a blood vessel carrying blood away from the heart) in the body. It carries oxygen-rich blood from the left ventricle of the heart to the body.inferior vena cava - a large vein (a blood vessel carrying blood to the heart) that carries oxygen-poor blood to the right atrium from the lower half of the body.left atrium - the left upper chamber of the heart. It receives oxygen-rich blood from the lungs via the pulmonary vein.left ventricle - the left lower chamber of the heart. It pumps the blood into the aorta.mitral valve - the valve between the left atrium and the left ventricle. It prevents the back-flow of blood from the ventricle to the atrium.pulmonary artery - the blood vessel that carries oxygen-poor blood from the right ventricle of the heart to the lungs.
pulmonary valve - the flaps between the right ventricle and the pulmonary artery. When the ventricle contracts, the valve opens, causing blood to rush into the pulmonary artery. When the ventricle relaxes, the valves close, preventing the back-flow of blood from the pulmonary artery to the right atrium.pulmonary vein - the blood vessel that carries oxygen-rich blood from the lungs to the left atrium of the heart.right atrium - the right upper chamber of the heart. It receives oxygen-poor blood from the body through the inferior vena cava and the superior vena cava.right ventricle - the right lower chamber of the heart. It pumps the blood into the pulmonary artery.septum - the muscular wall that separates the left and right sides of the heart.superior vena cava - a large vein that carries oxygen-poor blood to the right atrium from the upper parts of the body.tricuspid valve - the flaps between the right atrium and the right ventricle. It is composed of three leaf-like parts and prevents the back-flow of blood from the ventricle to the atrium.


Heart Anatomy Glossary
Human Anatomy
The heart is a fist-sized, muscular organ that pumps blood through the body. Oxygen-poor blood enters the right atrium of the heart (via veins called the inferior vena cava and the superior vena cava). The blood is then pumped into the right ventricle and then through the pulmonary artery to the lungs, where the blood is enriched with oxygen (and loses carbon dioxide). The oxygen-rich (oxygenated) blood is then carried back to the left atrium of the heart via the pulmonary vein. The blood is then pumped to the left ventricle, then the blood is pumped through the aorta and to the rest of the body. This cycle is then repeated. Every day, the heart pumps about 2,000 gallons (7,600 liters) of blood, beating about 100,000 times.
aorta - the biggest and longest artery (a blood vessel carrying blood away from the heart) in the body. It carries oxygen-rich blood from the left ventricle of the heart to the body.
inferior vena cava - a large vein (a blood vessel carrying blood to the heart) that carries oxygen-poor blood to the right atrium from the lower half of the body.
left atrium - the left upper chamber of the heart. It receives oxygen-rich blood from the lungs via the pulmonary vein.
left ventricle - the left lower chamber of the heart. It pumps the blood through the aortic valve into the aorta.
mitral valve - the valve between the left atrium and the left ventricle. It prevents the back-flow of blood from the ventricle to the atrium.
pulmonary artery - the blood vessel that carries oxygen-poor blood from the right ventricle of the heart to the lungs.
pulmonary valve - the flaps between the right ventricle and the pulmonary artery. When the ventricle contracts, the valve opens, causing blood to rush into the pulmonary artery. When the ventricle relaxes, the valves close, preventing the back-flow of blood from the pulmonary artery to the right atrium.
pulmonary vein - the blood vessel that carries oxygen-rich blood from the lungs to the left atrium of the heart.
right atrium - the right upper chamber of the heart. It receives oxygen-poor blood from the body through the inferior vena cava and the superior vena cava.
right ventricle - the right lower chamber of the heart. It pumps the blood into the pulmonary artery.
septum - the muscular wall that separates the left and right sides of the heart.
superior vena cava - a large vein that carries oxygen-poor blood to the right atrium from the upper parts of the body.
tricuspid valve - the flaps between the right atrium and the right ventricle. It is composed of three leaf-like parts and prevents the back-flow of blood from the ventricle to the atrium.














Label the Body DiagramLabel the human body diagram using the word list below.


anklearmbelly buttonchestchin
earelboweyefingersfoot
handheadheelhipknee
legmouthnoseneckshin
shoulderthightoeswaistwrist


Human Skeleton
Human Anatomy
The human skeleton consists of 206 bones. We are actually born with more bones (about 300), but many fuse together as a child grows up. These bones support your body and allow you to move. Bones contain a lot of calcium (an element found in milk, broccoli, and other foods). Bones manufacture blood cells and store important minerals. The longest bone in our bodies is the femur (thigh bone). The smallest bone is the stirrup bone inside the ear. Each hand has 26 bones in it. Your nose and ears are not made of bone; they are made of cartilage, a flexible substance that is not as hard as bone. Joints: Bones are connected to other bones at joints. There are many different types of joints, including: fixed joints (such as in the skull, which consists of many bones), hinged joints (such as in the fingers and toes), and ball-and-socket joints (such as the shoulders and hips). Differences between males and females: Males and females have slightly different skeletons, including a different elbow angle. Males have slightly thicker and longer legs and arms; females have a wider pelvis and a larger space within the pelvis, through which babies travel when they are born.


Label the Lungs Diagram
Read the definitions, then label the lung anatomy diagram below.
bronchial tree - the system of airways within the lungs, which bring air from the trachea to the lung's tiny air sacs (alveoli).cardiac notch - the indentation in the left lung that provides room for the heart.diaphragm - a muscular membrane under the lungs.larynx - a muscular structure at the top of the trachea, containing the vocal cords.left inferior lobe - the bottom lobe of the lung on the left side of the body.left superior lobe - the top lobe of the lung on the left side of the body.right inferior lobe - the bottom lobe of the lung on the right side of the body.right middle lobe - the middle lobe of the lung on the right side of the body.right superior lobe - the top lobe of the lung on the right side of the body.trachea (windpipe) - the tube through which air travels from the larynx to the lungs.



Skin Anatomy
Human Anatomy

The skin is an organ that forms a protective barrier against germs (and other organisms) and keeps the inside of your body inside your body, and keeps what's outside of your body outside. Skin also helps maintain a constant body temperature. Human skin is only about 0.07 inches (2 mm) thick.
Skin is made up of two layers that cover a third fatty layer. The outer layer is called the epidermis; it is a tough protective layer that contains melanin (which protects against the rays of the sun and gives the skin its color). The second layer (located under the epidermis) is called the dermis; it contains nerve endings, sweat glands, oil glands, and hair follicles. Under these two skin layers is a fatty layer of subcutaneous tissue (the word subcutaneous means "under the skin").
On average, an adult has from 18-20 square feet (about 2 square meters) of skin, which weighs about 6 pounds (2.7 kg).


blood vessels - Tubes that carry blood as it circulates. Arteries bring oxygenated blood from the heart and lungs; veins return oxygen-depleted blood back to the heart and lungs.dermis - (also called the cutis) the layer of the skin just beneath the epidermis.epidermis - the outer layer of the skin.hair follicle - a tube-shaped sheath that surrounds the part of the hair that is under the skin. It is located in the epidermis and the dermis. The hair is nourished by the follicle at its base (this is also where the hair grows).hair shaft - The part of the hair that is above the skin.hair erector muscle - a muscle is connected to each hair follicle and the skin - it contracts (in response to cold, fear, etc.), resulting in an erect hair and a "goose bump" on the skin.
melanocyte - a cell in the epidermis that produces melanin (a dark-colored pigment that protects the skin from sunlight).Pacinian corpuscle - nerve receptors that respond to pressure and vibration; they are oval capsules of sensory nerve fibers located in the subcutaneous fatty tissuesebaceous gland - a small, sack-shaped gland that releases oily (fatty) liquids onto the hair follicle (the oil lubricated and softens the skin). These glands are located in the dermis, usually next to hair follicles.sweat gland - (also called sudoriferous gland) a tube-shaped gland that produces perspiration (sweat). The gland is located in the epidermis; it releases sweat onto the skin.subcutaneous tissue - fatty tissue located under the dermis.


Label the Spine and SkullRead the definitions, then label the spine diagram below.

7 cervical vertebrae - 7 vertebrae located in the neck, below the skull. coccyx - 4 fused vertebrae located below the sacrum. 5 lumbar vertebrae - 5 vertebrae located below the thoracic vertebra and above the sacrum. sacrum - 5 fused vertebrae located below the lumbar region and above the coccyx. skull - the bones in the head that protect the brain. 12 thoracic vertebrae - 12 vertebrae in the mid-back, below the cervical vertebra and above the lumbar vertebrae.



Label Tongue Taste Areas Diagram
The tongue is a strong muscle in the mouth that is covered with papillae (small bumps on the tongue) and taste buds (that sense bitter, salty, sweet, and sour tastes). The taste buds are clustered along the sides of the tongue.
Read the descriptions, and then label the tongue below.
bitter - Bitter tastes (like the taste of tonic water) are mostly sensed towards the back and rear sides of the tongue. salty and sweet - Salty tastes and sweet tastes (like sugar) are mostly tasted at the tip of the tongue. sour - Sour tastes (like lemon juice) are mostly tasted at the sides of the tongue, at the middle and towards the front.




Label the Tooth

Read the definitions, and then label the tooth below.
Bone - the hard supportive tissue in which the tooth's root is anchored. Crown - the visible part of a tooth. Dentin - the hard but porous tissue located under both the enamel (and cementum) of the tooth. Dentin is harder than bone. Enamel - the tough, shiny, white outer surface of the tooth. Gum - the soft tissue that surrounds the base of the teeth.
Nerves and Blood Vessels - nerves transmit signals, and blood vessels carry nutrients to the tooth - they run through the tooth's root within the pulp. Pulp - the soft center of the tooth. The pulp contains blood vessels and nerves; it nourishes the dentin. Root - the anchor of a tooth that extends into the bone of the jaw. The number of human tooth roots ranges from one to four.





Tooth Anatomy




























People use their teeth to bite and chew food - they are the first step in the digestion of food. The long, sharp canine teeth tear up food (like meat). The wide, flat molars grind and mash up food. While we chew food, the tongue pushes the food to the teeth and saliva helps digestion and wets the food. Teeth also help us say certain sounds.
People have two sets of teeth in their lives, the primary teeth (also called the baby, milk or deciduous teeth) and the permanent teeth (also called the adult or secondary teeth). Children have 20 primary teeth; they are replaced by the permanent teeth by about age 13. Adults have 32 permanent teeth.
Primary Teeth:Most babies are born with no visible teeth -- the teeth are forming inside the gums. The 20 primary teeth (also called baby teeth or first teeth) erupt (poke through the gums) over the time from when a baby is from about 6 months to a year old.
Permanent Teeth:Primary teeth fall out and are replaced by 32 permanent teeth (also called the adult teeth). This happens over the time from when a child is from about 6 to 14 years old.
As a permanent tooth forms under the gums and in the jawbone, the roots of the primary tooth it is replacing dissolve. Then the primary tooth becomes loose and falls out. The permanent tooth will fill the space.
Wisdom Teeth:
Wisdom teeth (also called the third molars) are molars that usually erupt from the ages of 17 to 21. Tooth Glossary:
Cementum - a layer of tough, yellowish, bone-like tissue that covers the root of a tooth. It helps hold the tooth in the socket. The cementum contains the periodontal membrane.
Crown - the visible part of a tooth.
Dentin - the hard but porous tissue located under both the enamel and cementum of the tooth. Dentin is harder than bone.
Enamel - the tough, shiny, white outer surface of the tooth.
Gums - the soft tissue that surrounds the base of the teeth.
Nerves - nerves transmit signals (conveying messages like hot, cold, or pain) to and from the brain.
Periodontal membrane/ligament - the fleshy tissue between tooth and the tooth socket; it holds the tooth in place. The fibers of the periodontal membrane are embedded within the cementum.
Pulp - the soft center of the tooth. The pulp contains blood vessels and nerves; it nourishes the dentin.
Root - the anchor of a tooth that extends into the jawbone. The number of roots ranges from one to four.












Label the Teeth

Read the definitions below, then label the permanent teeth.

canine (also called cuspid) - the pointy tooth located between the incisors and the premolars. A canine tooth has 1 root. Adults have 4 canine teeth (2 in the top jaw and 2 in the bottom jaw). Canine means, "of or like a dog." incisors - the front teeth, used for cutting food. An incisor has 1 root. Adults have 8 incisors (4 in the top jaw and 4 in the bottom jaw). premolars (also called bicuspids) - the teeth located between the canine and the molars. A premolar tooth has 1 root. Bicuspids have two points (cusps) at the top. Adults have 8 premolars (4 in the top jaw and 4 in the bottom jaw). molars - the relatively flat teeth located towards the back of the mouth, used for grinding food. Molars in the top jaw have 3 roots; molars in the lower jaw have 2 roots. Adults have 12 molars (6 in the top jaw and 6 in the bottom jaw).








Label the Urinary Read the definitions, then label the urinary tract diagram below.

bladder - a hollow organ that stores urine until it is excreted. kidney - two bean-shaped organs that take waste from the blood and produce urine. ureter - two tubes, each of which carries urine from a kidney to the bladder. urethra - the tube that carries urine from the bladder out of the body.














External Genital Organs





The external genital organs include the mons pubis, labia majora, labia minora, Bartholin's glands, and clitoris. The area containing these organs is called the vulva. The external genital organs have three main functions:
· Enabling sperm to enter the body
· Protecting the internal genital organs from infectious organisms
· Providing sexual pleasure
The mons pubis is a rounded mound of fatty tissue that covers the pubic bone. During puberty, it becomes covered with hair. The mons pubis contains oil-secreting (sebaceous) glands that release substances that are involved in sexual attraction (pheromones). The labia majora (literally, large lips) are relatively large, fleshy folds of tissue that enclose and protect the other external genital organs. They are comparable to the scrotum in males. The labia majora contain sweat and sebaceous glands, which produce lubricating secretions. After puberty, hair appears on the labia majora.
The labia minora (literally, small lips) can be very small or up to 2 inches wide. The labia minora lie just inside the labia majora and surround the openings to the vagina and urethra. A rich supply of blood vessels gives the labia minora a pink color. During sexual stimulation, these blood vessels become engorged with blood, causing the labia minora to swell and become more sensitive to stimulation.
The area between the vaginal opening and the anus, below the labia majora, is called the perineum. It varies in length from almost 1 to more than 2 inches (2 to 5 centimeters).
The labia majora and the perineum are covered with skin similar to that on the rest of the body. The skin is thick, dry, and sometimes scaly. In contrast, the labia minora are lined with a mucous membrane, whose surface is kept moist by fluid secreted by specialized cells.
The opening to the vagina is called the introitus. The vaginal opening is the entryway for the penis during sexual intercourse and the exit for menstrual blood and vaginal discharge as well as a baby. When stimulated, Bartholin's glands (located beside the vaginal opening) secrete a thick fluid that supplies lubrication for intercourse. The opening to the urethra, which carries urine from the bladder to the outside, is located above and in front of the vaginal opening.
The clitoris, located between the labia minora at their upper end, is a small protrusion that corresponds to the penis in the male. The clitoris, like the penis, is very sensitive to sexual stimulation and can become erect. Stimulating the clitoris can result in an orgasm.

Internal Genital Organs
The internal genital organs form a pathway (the genital tract). This pathway consists of the following:
· Vagina (part of the birth canal), where sperm are deposited and from which a baby can emerge
· Uterus, where an embryo can develop into a fetus
· Fallopian tubes (oviducts), where a sperm can fertilize an egg
· Ovaries, which produce and release eggs
Sperm can travel up the tract, and eggs down the tract.


Internal Female Genital Organs
At the beginning of the tract, just inside the opening of the vagina, is the hymen, a mucous membrane. In virgins, the hymen usually encircles the opening like a tight ring, but it may completely cover the opening. The hymen helps protect the genital tract but is not necessary for health. It may tear at the first attempt at sexual intercourse, or it may be so soft and pliable that no tearing occurs. The hymen may also be torn during exercise or insertion of a tampon or diaphragm. Tearing usually causes slight bleeding. In women who have had intercourse, the hymen may be unnoticeable or may form small tags of tissue around the vaginal opening.
Vagina: The vagina is a narrow, muscular but elastic organ about 4 to 5 inches long in an adult woman. It connects the external genital organs to the uterus. The vagina is the main female organ of sexual intercourse. The penis is inserted into it. It is the passageway for sperm to the egg and for menstrual bleeding or a baby to the outside.
Usually, there is no space inside the vagina unless it is stretched open—for example, during an examination, sexual intercourse, or childbirth. The lower third of the vagina is surrounded by elastic muscles that control the diameter of its opening. These muscles contract rhythmically and involuntarily during orgasm.
The vagina is lined with a mucous membrane, kept moist by fluids oozing from cells on its surface and by secretions from glands in the cervix (the lower part of the uterus). A small amount of these fluids may pass to the outside as a clear or milky white vaginal discharge, which is normal. During a woman's reproductive years, the lining of the vagina has folds and wrinkles. Before puberty and after menopause (if the woman is not taking estrogen), the lining is smooth.
Uterus and Cervix: The uterus is a thick-walled, muscular, pear-shaped organ located in the middle of the pelvis, behind the bladder, and in front of the rectum. The uterus is anchored in position by several ligaments. The main function of the uterus is to sustain a developing fetus. The uterus consists of the cervix and the main body (corpus).
The cervix is the lower part of the uterus, which protrudes into the upper end of the vagina. It can be seen during a pelvic examination. Like the vagina, the cervix is lined with a mucous membrane, but the mucous membrane of the cervix is smooth.
Sperm can enter and menstrual blood can exit the uterus through a channel in the cervix. The channel is usually narrow, but during labor, the channel widens to let the baby through. The cervix is usually a good barrier against bacteria, except around the time an egg is released by the ovaries (ovulation), during the menstrual period, or during labor. Bacteria that cause sexually transmitted diseases (see Sexually Transmitted Diseases: Introduction) can enter the uterus through the cervix during sexual intercourse.
The channel through the cervix is lined with glands that secrete mucus. This mucus is thick and impenetrable to sperm until just before ovulation. At ovulation, the consistency of the mucus changes so that sperm can swim through it and fertilization can occur. At this time, the mucus-secreting glands of the cervix can store live sperm for up to about 5 days, but occasionally slightly longer. These sperm can later move up through the corpus and into the fallopian tubes to fertilize an egg. Almost all pregnancies result from intercourse that occurs during the 3 days before ovulation. However, pregnancies sometimes result from intercourse that occurs up to 6 days before ovulation or during the 3 days after ovulation. For some women, the time between a menstrual period and ovulation varies from month to month. Consequently, pregnancy can occur at different times during a menstrual cycle.
The corpus of the uterus, which is highly muscular, can stretch to accommodate a growing fetus. Its muscular walls contract during labor to push the baby out through the cervix and the vagina. During the reproductive years, the corpus is twice as long as the cervix. After menopause, the reverse is true.
As part of a woman's reproductive cycle (which usually lasts about a month), the lining of the corpus (endometrium) thickens. If the woman does not become pregnant during that cycle, most of the endometrium is shed and bleeding occurs, resulting in the menstrual period.
Fallopian Tubes: The two fallopian tubes, which are about 2 to 3 inches (about 5 to 7 centimeters) long, extend from the upper edges of the uterus toward the ovaries. The tubes do not directly connect with the ovaries. Instead, the end of each tube flares into a funnel shape with fingerlike extensions (fimbriae). When an egg is released from an ovary, the fimbriae guide the egg into the relatively large opening of a fallopian tube.
The fallopian tubes are lined with tiny hairlike projections (cilia). The cilia and the muscles in the tube's wall propel an egg downward through the tube to the uterus. The egg may be fertilized by a sperm in the fallopian tube (see Normal Pregnancy: Fertilization).
Ovaries: The ovaries are usually pearl-colored, oblong, and about the size of a walnut. They are attached to the uterus by ligaments. In addition to producing female sex hormones (estrogen and progesterone) and male sex hormones, the ovaries produce and release eggs. The developing egg cells (oocytes) are contained in fluid-filled cavities (follicles) in the wall of the ovaries. Each follicle contains one oocyte.






How Many Eggs?
A baby girl is born with egg cells (oocytes) in her ovaries. Between 16 and 20 weeks of pregnancy, the ovaries of a female fetus contain 6 to 7 million oocytes. Most of the oocytes gradually waste away, leaving about 1 to 2 million present at birth. None develop after birth. At puberty, only about 300,000—more than enough for a lifetime of fertility—remain. Only a small percentage of oocytes mature into eggs. The many thousands of oocytes that do not mature degenerate. Degeneration progresses more rapidly in the 10 to 15 years before menopause. All are gone by menopause.
Only about 400 eggs are released during a woman's reproductive life, usually one during each menstrual cycle. Until released, an egg remains dormant in its follicle-suspended in the middle of a cell division. Thus, the egg is one of the longest-lived cells in the body. Because a dormant egg cannot perform the usual cellular repair processes, the opportunity for damage increases as a woman ages. A chromosomal or genetic abnormality is thus more likely when a woman conceives a baby later in life.



All living things reproduce. Reproduction — the process by which organisms make more organisms like themselves — is one of the things that sets living things apart from nonliving things. But even though the reproductive system is essential to keeping a species alive, unlike other body systems it's not essential to keeping an individual alive.

In the human reproductive process, two kinds of sex cells, or gametes, are involved. The male gamete, or sperm, and the female gamete, the egg or ovum, meet in the female's reproductive system to create a new individual. Both the male and female reproductive systems are essential for reproduction.
Humans, like other organisms, pass certain characteristics of themselves to the next generation through their genes, the special carriers of human traits. The genes parents pass along to their offspring are what make kids similar to others in their family, but they're also what make each child unique. These genes come from the father's sperm and the mother's egg, which are produced by the male and female reproductive systems.
Understanding the male reproductive system, what it does, and the problems that can affect it can help you better understand your son's reproductive health.
About the Male Reproductive System
Most species have two sexes: male and female. Each sex has its own unique reproductive system. They are different in shape and structure, but both are specifically designed to produce, nourish, and transport either the egg or sperm.
Unlike the female, whose sex organs are located entirely within the pelvis, the male has reproductive organs, or genitals, that are both inside and outside the pelvis. The male genitals include:
· the testicles
· the duct system, which is made up of the epididymis and the vas deferens
· the accessory glands, which include the seminal vesicles and prostate gland
· the penis
In a guy who has reached sexual maturity, the two testicles, ortestes, produce and store millions of tiny sperm cells. The testicles are oval-shaped and grow to be about 2 inches (5 centimeters) in length and 1 inch (3 centimeters) in diameter. The testicles are also part of the endocrine system because they produce hormones, including testosterone. Testosterone is a major part of puberty in boys, and as a guy makes his way through puberty, his testicles produce more and more of it. Testosterone is the hormone that causes boys to develop deeper voices, bigger muscles, and body and facial hair, and it also stimulates the production of sperm.
Alongside the testicles are the epididymis and the vas deferens, which make up the duct system of the male reproductive organs. The vas deferens is a muscular tube that passes upward alongside the testicles and transports the sperm-containing fluid called semen. The epididymis is a set of coiled tubes (one for each testicle) that connects to the vas deferens.
The epididymis and the testicles hang in a pouch-like structure outside the pelvis called the scrotum. This bag of skin helps to regulate the temperature of testicles, which need to be kept cooler than body temperature to produce sperm. The scrotum changes size to maintain the right temperature. When the body is cold, the scrotum shrinks and becomes tighter to hold in body heat. When it's warm, the scrotum becomes larger and more floppy to get rid of extra heat. This happens without a guy ever having to think about it. The brain and the nervous system give the scrotum the cue to change size.
The accessory glands, including the seminal vesicles and the prostate gland, provide fluids that lubricate the duct system and nourish the sperm. The seminal vesicles are sac-like structures attached to the vas deferens to the side of the bladder. Theprostate gland, which produces some of the parts of semen, surrounds the ejaculatory ducts at the base of the urethra, just below the bladder. The urethra is the channel that carries the semen to the outside of the body through the penis. The urethra is also part of the urinary system because it is also the channel through which urine passes as it leaves the bladder and exits the body.
The penis is actually made up of two parts: the shaft and theglans. The shaft is the main part of the penis and the glans is the tip (sometimes called the head). At the end of the glans is a small slit or opening, which is where semen and urine exit the body through the urethra. The inside of the penis is made of a spongy tissue that can expand and contract.
All boys are born with a foreskin, a fold of skin at the end of the penis covering the glans. Some boys are circumcised, which means that a doctor or clergy member cuts away the foreskin. Circumcision is usually performed during a baby boy's first few days of life. Although circumcision is not medically necessary, parents who choose to have their children circumcised often do so based on religious beliefs, concerns about hygiene, or cultural or social reasons. Boys who have circumcised penises and those who don't are no different: All penises work and feel the same, regardless of whether the foreskin has been removed.
What the Male Reproductive System Does
The male sex organs work together to produce and release semen into the reproductive system of the female during sexual intercourse. The male reproductive system also produces sex hormones, which help a boy develop into a sexually mature man during puberty.
When a baby boy is born, he has all the parts of his reproductive system in place, but it isn't until puberty that he is able to reproduce. When puberty begins, usually between the ages of 10 and 14, the pituitary gland — which is located near the brain — secretes hormones that stimulate the testicles to produce testosterone. The production of testosterone brings about many physical changes. Although the timing of these changes is different for every guy, the stages of puberty generally follow a set sequence.
· During the first stage of male puberty, the scrotum and testes grow larger.
· Next, the penis becomes longer, and the seminal vesicles and prostate gland grow.
· Hair begins to appear in the pubic area and later it grows on the face and underarms. During this time, a male's voice also deepens.
· Boys also undergo a growth spurt during puberty as they reach their adult height and weight.
A male who has reached puberty will produce millions of sperm cells every day. Each sperm is extremely small: only 1/600 of an inch (0.05 millimeters long). Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules. At birth, these tubules contain simple round cells, but during puberty, testosterone and other hormones cause these cells to transform into sperm cells. The cells divide and change until they have a head and short tail, like tadpoles. The head contains genetic material (genes). The sperm use their tails to push themselves into the epididymis, where they complete their development. It takes sperm about 4 to 6 weeks to travel through the epididymis.
The sperm then move to the vas deferens, or sperm duct. The seminal vesicles and prostate gland produce a whitish fluid calledseminal fluid, which mixes with sperm to form semen when a male is sexually stimulated. The penis, which usually hangs limp, becomes hard when a male is sexually excited. Tissues in the penis fill with blood and it becomes stiff and erect (an erection). The rigidity of the erect penis makes it easier to insert into the female's vagina during sexual intercourse. When the erect penis is stimulated, muscles around the reproductive organs contract and force the semen through the duct system and urethra. Semen is pushed out of the male's body through his urethra — this process is called ejaculation. Each time a guy ejaculates, it can contain up to 500 million sperm.
When the male ejaculates during intercourse, semen is deposited into the female's vagina. From the vagina the sperm make their way up through the cervix and move through the uterus with help from uterine contractions. If a mature egg is in one of the female's fallopian tubes, a single sperm may penetrate it, and fertilization, or conception, occurs.
This fertilized egg is now called a zygote and contains 46 chromosomes — half from the egg and half from the sperm. The genetic material from the male and female has combined so that a new individual can be created. The zygote divides again and again as it grows in the female's uterus, maturing over the course of the pregnancy into an embryo, a fetus, and finally a newborn baby.
Things That Can Go Wrong With the Male Reproductive System
Boys may sometimes experience reproductive system problems, including:
Disorders of the Scrotum, Testicles, or EpididymisConditions affecting the scrotal contents may involve the testicles, epididymis, or the scrotum itself.
· Testicular trauma. Even a mild injury to the testicles can cause severe pain, bruising, or swelling. Most testicular injuries occur when the testicles are struck, hit, kicked, or crushed, usually during sports or due to other trauma. Testicular torsion, when one of the testicles twists around, cutting off its blood supply, is also a problem that some teen males experience, although it's not common. Surgery is needed to untwist the cord and save the testicle.
· Varicocele. This is a varicose vein (an abnormally swollen vein) in the network of veins that run from the testicles. Varicoceles commonly develop while a boy is going through puberty. A varicocele is usually not harmful, although it can damage the testicle or decrease sperm production. Take your son to see his doctor if he is concerned about changes in his testicles.
· Testicular cancer. This is one of the most common cancers in men younger than 40. It occurs when cells in the testicle divide abnormally and form a tumor. Testicular cancer can spread to other parts of the body, but if it's detected early, the cure rate is excellent. Teen boys should be encouraged to learn to perform testicular self-examinations.
· Epididymitis is inflammation of the epididymis, the coiled tubes that connect the testes with the vas deferens. It is usually caused by an infection, such as the sexually transmitted disease chlamydia, and results in pain and swelling next to one of the testicles.
· Hydrocele. A hydrocele occurs when fluid collects in the membranes surrounding the testes. Hydroceles may cause swelling in the scrotum around the testicle but are generally painless. In some cases, surgery may be needed to correct the condition.
· Inguinal hernia. When a portion of the intestines pushes through an abnormal opening or weakening of the abdominal wall and into the groin or scrotum, it is known as an inguinal hernia. The hernia may look like a bulge or swelling in the groin area. It can be corrected with surgery.
Disorders of the Penis
Disorders affecting the penis include:
· Inflammation of the penis. Symptoms of penile inflammation include redness, itching, swelling, and pain. Balanitis occurs when the glans (the head of the penis) becomes inflamed. Posthitis is foreskin inflammation, which is usually due to a yeast or bacterial infection.
· Hypospadias. This is a disorder in which the urethra opens on the underside of the penis, not at the tip.
· Phimosis. This is a tightness of the foreskin of the penis and is common in newborns and young children. It usually resolves itself without treatment. If it interferes with urination, circumcision (removal of the foreskin) may be recommended.
· Paraphimosis. This may develop when a boy's uncircumcised penis is retracted but doesn't return to the unretracted position. As a result, blood flow to the head of the penis may be impaired, and your son may experience pain and swelling. A doctor may use lubricant to make a small incision so the foreskin can be pulled forward. If that doesn't work, circumcision may be recommended.
· Ambiguous genitalia. This occurs when a child is born with genitals that aren't clearly male or female. In most boys born with this disorder, the penis may be very small or nonexistent, but testicular tissue is present. In a small number of cases, the child may have both testicular and ovarian tissue.
· Micropenis. This is a disorder in which the penis, although normally formed, is well below the average size, as determined by standard measurements.
If your son has symptoms of a problem with his reproductive system or he has questions about growth and sexual development, talk with your doctor — many problems with the male reproductive system can be treated.