(ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿá†ò“ ¬ L 2óêÂ첑2à!o#B%¿&F(¶)¾*Ù+O-Æ/<1U2x3­5·6ˆ8~::<ÿÿÿÿ°Index Welcome to the Body Adventure index. Just click on a letter to access a subject of interest. It is also possible to go directly to a subject by typing the word at any time. ™The Hand The most versatile part of the skeleton, the hand enables people to grasp and manipulate objects. It is comprised of the wrist (carpal bones), palm (metacarpals) and fingers (phalanges). Movement and sensation are supplied by three main nerves, the median nerve, the ulnar nerve and the radial nerve. Movements are achieved largely via tendons which connect the forearm muscles to the bones of the hand. _The Heart The heart consists of the two atria which receive blood, and the two ventricles which pump blood to the lungs and the body. There are four valves which ensure that blood flow is always in the right direction. With each beat, the right ventricle pumps deoxygenated blood to the lungs, and the left ventricle pumps newly oxygenated blood to the rest of the body. The heart beats more than 2.5 billion times during an average lifetime. The heart is a more energy efficient pump than any ever designed by man. In this detailed model of the heart, the four chambers and the great vessels are all well seen. Antibodies Antibodies serve as an important part of the immune system. Antibodies are made in response to exposure to common pathogens like viruses and bacteria. Antibodies are very specific and will only stick to the surface of the microorganism or other particle that elicited their production. Here several antibodies are shown as they attach to foreign particles within the bloodstream. The Brain The brain is the organ which controls our thoughts, speech, emotions and actions. The brain is also the control center for all of the bodies vital functions including breathing, heartbeat, and temperature. In humans, the largest part of the brain is the cerebrum with its many deep folds. These folds greatly increase the surface area of the cerebral cortex. Many functions such as sight, hearing, sensation and voluntary movement have been shown to be processed by very specific regions of the cerebral cortex. þBronchioles and Alveoli At their very end the bronchioles branch into many tiny air sacs called alveoli. The alveoli are lined with cells that have very thin walls. The tiny blood vessels which travel through these cell walls are only big enough to allow one red blood cell to pass through at a time. The air that we breathe thus comes into close contact with the individual blood cells. In the lungs, the blood cells unload carbon dioxide which is breathed out and pick up oxygen which is then delivered to the rest of the body. ’The Carina The trachea divides into right and left mainstem bronchi at the carina. This picture was taken with a bronchoscope which is used for looking down into the airways. Doctors use the bronchoscope to look directly at the airways within the lungs. The bronchoscope can also be used to remove foreign objects from the airways or to take small tissue samples which help in the diagnosis of lung diseases. ÊThe Inside of the Colon. Like the stomach and the small intestine, the colon can be looked at by endoscopy. The test, called colonoscopy, is performed by inserting a flexible tube into the rectum. Like the endoscope used to look at the upper GI tract, the colonoscope has a light and a lens at its end. This photograph shows the inside of the colon as seen through a colonoscope. The inside of the colon is characterized by its periodic purse string indentations called haustra. ´The Colon A watery mixture of undigested food passes from the small intestine into the large intestine or colon. The colon is a large muscular tube that consists of four sections: the ascending colon, the transverse colon, the descending colon and the sigmoid colon. Within the colon, excess water is reabsorbed and feces is formed. Rhythmic contractions of the colon called peristalsis serve to move the feces along the length of the colon. Body Adventure Move the mouse to rotate the body and then click to bring up the cursor. If you like the demo and want to get the complete Body Adventure on either CD ROM or diskette, ask for the product at a store near you or call Knowledge Adventure direct at 1-800-542-4240. ÍThe Eardrum The eardrum or tympanic membrane vibrates in response to sound waves. These vibrations are then transferred to the inner ear by the movement of the tiny bones (ossicles) of the middle ear. There are three of these bones which are called the malleus (hammer), incus (anvil) and the stapes (stirrup). The malleus is attached directly to the eardrum and the incus. The incus is attached to the stapes which is connected to the inner ear via the oval window. ¹Hair Cells of the Inner Ear The vibrations caused by sound are transmitted to the inner ear by the movement of the stapes within the oval window. This movement creates waves in the fluid of the inner ear. Within the inner ear, there are orderly rows of hair cells which respond to sounds of differing frequency. The hair cells are stimulated to send messages to the brain by the movement of the fluid waves. It is these messages that the brain perceives as hearing. The Stomach seen by Endoscopy Physicians can look at the inside of the stomach using an instrument called an endoscope. The endoscope is a flexible tube with a light and a lens at its end. This photograph shows what the inside of the stomach looks like when seen through an endoscope. The stomach is actually a strong muscle which helps break down food by mechanical action and secretion of acid. The stomach lining also secretes a mucous coating which protects it from the acid. Sometimes, the mucous barrier is disrupted resulting in an ulcer. Female Reproductive System The female reproductive system consists of the uterus, the fallopian tubes, and the two ovaries. During a woman's fertile years, an ovum is released each month by one of the ovaries. The fallopian tube has a feathered opening near the ovary which picks up the ovum and then provides passageway to the uterus. Fertilization will generally occur in the fallopian tube. The newly formed zygote will then complete its trip down the fallopian tube and implant within the uterine wall where development will take place. ‰The Coronary Arteries The tissue of the heart is called the myocardium. The heart has a high metabolism and requires a large oxygen supply. Blood flow to the myocardium itself is supplied by the coronary arteries which take off from the aorta just after its connection with the heart. Most blood flow to the heart occurs during its relaxation phase (diastole) rather than during the contraction phase (systole). ¾The Heart's Conduction System The heart is comprised of cells that will automatically contract rythmically for as long as they have nutrients and oxygen. Normally, the signal to begin a contraction starts at the sinoatrial node in the right atrium. This signal then propagates through the atrioventricular node and down to reach all parts of the ventricles. The heart usually beats about sixty to eighty times per minute, pumping about one pint of blood with each stroke. ‰The Auditory Pathway Sound waves are channeled into the ear by the external ear which is called the pinna. The sound waves then travel through the auditory canal until they reach the eardrum. The eardrum vibrates in response to these sound waves. Movement of the eardrum is conveyed by the bones of the middle ear to the inner ear. Within the inner ear, the sound is detected and a signal is sent to the brain.  Hemoglobin Red blood cells are completely filled with hemoglobin, a special molecule designed to carry around oxygen and carbon dioxide. Red blood cells have no nuclei which enables more hemoglobin to fit within each cell. The hemoglobin molecule is comprised of four basic units. In the adult human there are two alpha chains and two beta chains. Sickle cell disease is a common illness resulting from a single small substitution in the beta chains. There is also a single iron atom in the center of each hemoglobin molecule which is needed to carry around the oxygen or carbon dioxide. This is why iron supplements are sometimes taken to help treat anemia (low blood level). €The Kidneys This colorful illustration shows an artist's view of the kidneys. The two kidneys function both to remove wastes from the body, and to regulate the amount of salt and water within the body. The kidneys also produce several important hormones such as erythropoietin which regulates the production of red blood cells and renin which plays a role in the regulation of blood pressure. ÅThe Larynx The large circular structure in this picture is the larynx. The two smaller structures sitting above the larynx are the arytenoid cartilages. The front of the larynx is often called the Adam's apple. The vocal cords strech between the two arytenoid cartilages and the Adam's apple. The two vocal cords vibrate when air from the lungs passes over them. These vibrations make sounds which are modifed by the palate, tongue and lips to form speech. pThe Liver The liver is the largest internal organ in the body. The liver produces many important proteins and substances as well as being the major route for detoxifying harmful chemicals. It is also the place where absorbed food travels first to be processed and packaged for use by the rest of the body. The liver thus serves as the main chemical factory within the body. iThe Liver and Gall Bladder One of the important functions of the liver is the production of bile. Bile is secreted into the biliary tree (shown in green), and then concentrated in the gall bladder. The gall bladder releases the bile into the small intestine at the same time the stomach empties food into the small intestine. The bile helps to make fats in our food easier to digest. cThe Lungs People are dependent on breathing to supply oxygen for use by all the cells of the body and to get rid of carbon dioxide. The airways of the lungs begin with the trachea and then branch again and again to form very small airways called bronchioles. The bronchioles lead to tiny air sacs where the air we breathe comes into contact with the blood supply. øA Lymph Node Antibodies are made by immune cells known as lymphocytes. Lymphocytes mature and do much of their work within lymph nodes. In the lymph nodes the lymphocytes interact with other important immune cells to eliminate foreign material from the body. Nerve Fibers Often the axons of many neurons will be bundeled together to form nerve fibers. These fibers connect the central nervous system with the rest of the body. Both sensation and movement are dependent on these nerve fibers which carry the messages throughout the body. _The Small Intestine The stomach empties its partially digested food into the small intestine where the process of digestion is completed. Within the small intestine food is broken down into tiny particles which are then absorbed. The small intestine is essentially a long muscular tube with a special lining designed to enable absorption of these tiny food particles. dA Single Neuron The nervous system is comprised of the brain, spinal cord, and peripheral nerves. The basic function of the nervous system is to transmit messages from one place to another. The cells which do this job are called neurons. Neurons can vary widely in their shape, but they all have several basic things in common. Like all cells there is a cell body. The cell body has many short branches coming off of it called dendrites which allow communication with nearby neurons. The body also has a single long branch called the axon which permits messages to be carried to distant neurons in other parts of the body. cOvum with Sperm Many sperm are seen on the surface of this single ovum. Only one of the sperm will penetrate into the ovum. After this, the ovum surface undergoes a change which prevents any other sperm from entering. Following fertilization, the genetic material (DNA) from the ovum and the sperm combine to form the single cell which will develop into a new person. The Pancreas The pancreas serves two very important roles. It secretes enzymes which help to digest food, and it produces enzymes which are released into the blood. Insulin is one of these latter enzymes which is needed by the body to regulate sugar levels within the blood. Red Blood Cell This tiny biconcave disk is a single red blood cell. Red blood cells serve to carry oxygen to every part of the body as well as carrying carbon dioxide back to the lungs. Red blood cells are made in the marrow of bones and have an average lifespan of about ninety days. Skeletal Muscle Cells Muscle cells form fibers that permit movement through coordinated contraction and relaxation. There are three different types of muscle in the body: skeletal muscle, smooth muscle and cardiac muscle. This photograph shows skeletal muscle fibers which are responsible for voluntary movement of the body such as running and jumping. Smooth muscle is found within the organs and is not under conscious control. The cardiac muscle has the unique property of rythmically contracting on its own without a need for constant direction to do so. ýThe Skull The skull is comprised of the cranium and the facial bones. The cranium is the hard and flat part of the skull which surrounds the delicate brain and protects it from harm. The skull also serves to house the senses of sound, sight, smell and taste. ÃThe Testes The two testicles function to produce sperm and testosterone (the male sex hormone). Within the testicles are innumerable delicate tubes called seminiferous tubules in which the sperm are made. The seminiferous tubules lead via the vas efferens to the epididymis where the newly formed sperm mature. The sperm each have a small head containing the genetic material (DNA) and a long tail that is used to swim through the female reproductive system. ÝNormal Bone Structure Bones are not simply solid. Instead, they have a complex stucture with a surface layer (periosteum) and a cortex made of hard dense bone which surrounds the internal spongy bone. The bone marrow in which the blood cells are made lies within the spongy bone. The complex structure of the spongy bone is shown in this photograph. All bone is characterized by an orderly cartilaginous framework that is mineralized with calcium and phosphorus to make it resilient and strong. ¥Tracheal Epithelium The trachea and larger bronchi have a special lining. This purpose of this lining is to remove the little particles that get into our lungs from the air that we breathe. The lining has two types of cells, goblet cells and ciliated cells. The goblet cells secrete sticky mucous that traps particles. The ciliated cells are covered with tiny hairs that rhythmically beat to move the particles up and out of the lungs. {The Ureters The ureters are the long tubes which connect the kidneys to the bladder. The ureters have muscular walls which serve to propel urine down into the bladder via a wavelike pumping action called peristalsis. The ureters tunnel through the bladder wall at an angle which helps keep urine from refluxing back up into the kidneys. The bladder is then emptied through the urethra.