This animation shows the passage of allergens (pollen) into the nasal cavity. The body response includes the release of histamine, a chemical that produces allergy symptoms in the body.Launch animation

This animation shows the brain and the changes that occur to it from Alzheimer's disease.Launch animation

This animation illustrates and compares the severity of an ankle sprain (Type I, II, III).Launch animation

This animation shows the cardiac conduction system and the arrhythmias of a fast and slow beating heart.Launch animation

This animation illustrates the location of basal ganglia in the brain. Injury to the basal ganglia may result in athetosis (constant writhing movements of the body).Launch animation

This animation shows the use of balloon angioplasty to open a narrowed coronary artery lumen caused by deposits of plaque.Launch animation

This animation shows the neurological control of normal bladder function.Launch animation

This animation shows the eyes response to invading foreign substances, resulting in blinking and the lacrimal glands production of tears which then pass into the nose through tear ducts.Launch animation

This animation depicts the process of blood clotting in an enlarged view of a small artery. Cells shown include red blood cells, platelets, fibrin, and clotting factors.Launch animation

This animation shows the cycle of blood circulation through the heart, arteries, veins, and lungs within the body.Launch animation

This animation defines normal blood pressure and the measurement of systole and diastole. Structures shown include a front-view of the heart beating, a cut-view of the heart beating, and blood flowing through a small artery.Launch animation

This animation shows one method in which a severe wrist fracture is treated by inserting a bone graft from the hip followed by fixation with a metal plate and screws.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the brain. Rotate the brain or pick from a list of terms to identify various structures.Launch animation

This animation highlights the major sections of the brain and explains their primary functions.Launch animation

This animation shows a breast reduction (lift) procedure.Launch animation

This animation illustrates the major structures of the respiratory system and shows the mechanism of breathing (respiration).Launch animation

This animation shows the formation of a bunion.Launch animation

From a top view of the voice box (larynx) and vocal cords, this animation shows the formation of a malignant tumor on the right vocal cord.Launch animation

This animation illustrates the cardiac conduction system, a group of specialized muscle cells that signal the rest of the heart to contract. An ECG tracing is shown in tandem with a normal heart beat.Launch animation

This animation shows a catheter being inserted into the heart where alcohol is injected causing the swollen ventricle wall to shrink.Launch animation

This animation displays a normal heart beating. Also shown are red blood cells traveling through an enlarged cut-section of a small artery and the percentage of the bloods components.Launch animation

This animations depicts how a cataract is seen in the eye.Launch animation

This animation traces the growth and migration of a fertilized egg cell through the fallopian tubes to the uterine lining. Enlarged views show the action of cilia in the fallopian tube transporting the egg and its implantation into the uterine lining.Launch animation

This animation shows a cerebral aneurysm growing and rupturing filling the brain with blood.Launch animation

This interactive animation shows the process of cervical dilation during labor.Launch animation

This animation describes and depicts the common reasons for having a cesarean section delivery. The location of an epideral application is shown in a side view followed by a Cesarean section delivery illustrated in both side and front views.Launch animation

This animation shows an enlarged view of a section of skin, highlighting its layers and various structures.Launch animation

This animation shows the process of conception in which a sperm unites with an egg cell to form a fertilized egg.Launch animation

This interactive animation takes you on a journey through the female reproductive system to see the processes of ovulation, fertilization and implantation of a fertilized egg (zygote).Launch animation

This animation shows the process in which an egg cell is fertilized by a sperm cell to form a fertilized egg (zygote).Launch animation

In a microscopic view, this animations shows the conception of identical (maternal) twins.Launch animation

This animations shows the head receiving two impacts. One on the front, and one on the side from a boxing glove.Launch animation

This animation shows corneal infections resulting from corneal injury.Launch animation

This animation shows a coronary artery bypass graft (CABG) procedure in which a portion of vein is grafted on the heart to reroute blood from a blocked section of a coronary artery.Launch animation

Shown in an enlarged view of a damaged coronary artery is the build-up of plaque and restriction of blood flow, progressing to complete arterial blockage and heart muscle ischemia (heart attack). Anteriorly, a normal heart beating is also illustrated.Launch animation

This animation describes a series of cosmetic surgeries, including forehead lift, eyelid lift, and facelift.Launch animation

This animation shows the mechanism of coughing caused by an irritant entering the windpipe (larynx), resulting in its dislodgement. The steps of the coughing reflex are shown from a side view of the body in tandem with a top view of the vocal cords.Launch animation

This animations depicts changes to the retina resulting from diabetes mellitus.Launch animation

This animation highlights the major parts of the digestive system and follows the breakdown of celery from consumption to excretion.Launch animation

This animation shows a Directional Coronary Atherectomy (DCA) procedure performed to remove the blockage from the coronary arteries by a tiny spinning cutter that slices away plaque lesions and stores them to be withdrawn.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the ear. Rotate the ear or pick from a list of terms to identify various structures.Launch animation

This animation shows the signs of the first phase of labor (early labor).Launch animation

This animation depicts the maturation of egg cells within ovary and illustrates the role of hormones in menstruation and egg cell fertilization and implantation.Launch animation

This animation illustrates the development cycle of an egg in an ovary and the sequence of events to fertilization of the egg or not.Launch animation

An electrocardiogram (ECG) enables the rhythm of the heart to be viewed in waveform. This interactive animation shows the ECG waveforms for normal sinus rhythm and various conditions of the heart.Launch animation

This animation illustrates the glands of the endocrine system, specifically enlarging the pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, and pancreas. A communication path within the neuroendocrine system is also shown.Launch animation

This animation illustrates the prostate gland and its surrounding structures and shows the effects of benign prostatic hypertrophy (BPH).Launch animation

This animation illustrates the prostate gland and its surrounding structures and shows the effects of benign prostatic hypertrophy (BPH).Launch animation

This animation shows the release of epinephrine and its effect of the heart.Launch animation

This animation gives a general comparison between anaerobic exercise (lifting weights) and aerobic exercise (jogging).Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the eye. Rotate the eye or pick from a list of terms to identify various structures.Launch animation

This animation shows the bodys response to a bee sting on the nose, giving a general description of the communication between the peripheral nervous system detecting the pain and the central nervous system issuing a reactive response.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the female reproductive system. Rotate to or pick from a list of terms to identify various structures of the system.Launch animation

Creating a new life is nothing short of a miracle. With the fetal development interactive tool, you can get an insider's view of a baby in the making - from conception to term. You can watch the entire development, specify portions of the pregnancy, or freeze the frame on a specific week by dragging the slider bars back and forth.Launch animation

This animation illustrates the development of a babys outer ear from its embryonic origins. Structures of a babys middle and inner ear are also shown from the front view.Launch animation

This animation shows the differences between the development of a single baby, identical twins, and non-identical twins.Launch animation

This animation illustrates the passage of air and exchange of oxygen and carbon dioxide within the lungs on both a gross and microscopic level.Launch animation

This animation shows the affects of untreated glaucoma.Launch animation

This animation shows uric acid crystals moving to the big toe joint causing pain.Launch animation

Through a series of magnifications of the ear, this animation depicts the movement, amplification, translation, and interpretation of sound waves traveling through the ears three regions, ultimately becoming neural messages sent to the brain.Launch animation

This animation shows the various structures of the ear and the process of hearing.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the heart. Rotate the heart, view in transparent mode, or pick from a list of terms to take you to various structures.Launch animation

This animation shows the procedure of a heart bypass surgery.Launch animation

This animation shows the development of the fetal heart from day 18 to day 57. A functional comparison is made between a fetal and newborn heart.Launch animation

This animation follows the passage of blood through the hearts chambers and valves.Launch animation

This animation depicts how certain ingested foods can cause regurgitation of the stomachs contents back into the esophagus resulting in the sensation of heartburn. The relationship between the location of the esophagus and heart is shown in a front view of the body.Launch animation

This animation shows displacement of an intervertebral disk (disk between the vertebrae).Launch animation

This animation depicts the process of maintaining homeostasis in the body through hormonal negative feedback mechanisms. An analogy is made between thermostat temperature regulation in a home to the hormonal control of sugar levels within the bloodstream.Launch animation

This animation shows the formation of a fetal face during the early weeks of development.Launch animation

This animation shows the effects of hypertension on a cerebral artery.Launch animation

This animation shows an enlarged view of femoral bone marrow containing immature specialized white blood cells (lymphocytes) and depicts their maturation and migration into either B cell or T cell lymphocytes.Launch animation

This animations shows the process of Intracytoplasmic sperm injection (ICSI), a procedure used to fertilize an egg cell outside of the body.Launch animation

This animation begins with an front view of the urinary tract and continues with the formation of kidney stones shown in a cut-section of the kidney. Severities of kidney stones are depicted, demonstrating various degrees of urine obstruction.Launch animation

This animation gives a cartooned comical view of birth through a vaginal delivery.Launch animation

Illustrated for a childs perspective, this animation depicts the growth of a baby within a uterus from the first month to the ninth month of pregnancy.Launch animation

Illustrated for a childs perspective, this cartooned animation explains the sperms role in determining if a baby will be a girl or a boy.Launch animation

Illustrated for a childs perspective, this cartooned animation explains how food and air are supplied from the mother to the baby through it's umbilical cord.Launch animation

Created for a childs perspective, this cartooned animation illustrates the appearance and origin of a sperm cell and egg cell as well as the development of a baby within the uterus.Launch animation

A vibrating suction cannula is shown removing abdominal fat.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the lungs. Rotate the lungs view in transparent mode, or pick from a list of terms to take you to various structures of the lungs.Launch animation

This animation shows an enlarged view of one lymph node filtering out micro-organisms from the fluid passing through.Launch animation

This animation discusses and depicts several aspects of the lymphatic system including a microscopic view of lymph formation, edema, breast lymphatics and the spread of breast cancer.Launch animation

This animation shows the process of macular degeneration in the eye.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the male reproductive system. Rotate to or pick from a list of terms to identify various structures of the system.Launch animation

This interactive animation shows the changes that occur during the menstrual cycle to hormone levels, body temperature, an ovary, and lining of the uterus.Launch animation

This animation discusses the four functions of muscle and displays the three different types of muscle tissue in external and microscopic views.Launch animation

This animation provides a general overview of the nervous system and shows the process in which nerve impulses are transmitted.Launch animation

This animation shows the early formation of the nervous system.Launch animation

This animation shows an enlargement of a blood capillary with red blood cells traversing through it. A section of the artery is enlarged further to display the exchange of oxygen and carbon dioxide between a capillary and its surrounding tissue.Launch animation

This animation compares the a normal adult knee joint and a knee joint affected by osteoarthritis.Launch animation

This animation begins by showing a hip fracture due to osteoporosis (fracture in neck of the femur, anterior view). The bone then dissolves into a frontal section to compare the bony interior of a normal femur to that of an osteoporotic femur.Launch animation

This animations shows the process of ovulation (the release a single egg cell from an ovary).Launch animation

This animations shows sporatic brain activity and a twitching hand that occur with Parkinson's disease, followed by treatment with dopamine stimulation.Launch animation

This animation shows a Percutaneous Transluminal Coronary Angioplasty (PTCA) procedure to open up blocked coronary arteries by inflating a tiny balloon to compress the plaque against the walls of the artery, flattening it out so that blood can once again flow through the blood vessel freely.Launch animation

This animation follows the processing of food through the digestive tract, focusing on the intestinal peristaltic movement (a series of wave-like muscle contractions that moves the food mixture down the digestive tract).Launch animation

This animation shows the process of a macrophage ingesting a foreign substance.Launch animation

This animation describes the regulation of the pituitary gland and the hormones it releases to regulate various organs and processes in the body.Launch animation

This animation illustrates the delivery of the placenta by strong uterine contractions and gentle abdominal pressure applied by a physician.Launch animation

This animation illustrate the formation of the placenta and blood barrier and their role in providing the embryo with nutrients and oxygen, removing waste products, and preventing harmful substance from entering in.Launch animation

This animation depicts hypertension caused by pre-eclampsia that adversely affects the fetus by causing constriction of the placental arteries.Launch animation

This animation illustrates the development cycle of an egg in an ovary and the sequence of events to fertilization of the egg or not.Launch animation

This animation shows the process of red blood cell formation and the components that comprise blood.Launch animation

This animation shows the bodys reflex response to a hot substance landing on the hand.Launch animation

This animation shows the process in which light is transformed by the retina as electical impulses that travel to the brain through the optic nerve.Launch animation

This animation shows a retinal detachment injury.Launch animation

In a side view of the body with the baby in utero, the mucous plug (bloody show) is illustrated followed by the rupturing of the amniotic sac (water breaking), indicating the onset of labor.Launch animation

This animation illustrates the various structures of the eye and how the shape of the eye affects vision (nearsightedness and farsightedness).Launch animation

This animation illustrates the development of the external sex organs in a female and male fetus.Launch animation

This animation shows a dislocation of the shoulder joint.Launch animation

This animation details the components of the fetal skeletal system and illustrates the process of bone development through ossification of the membranes and cartilage.Launch animation

This animation illustrates the organization of skeletal muscle, enlarging from a muscle belly up to its myofibrils. Simultaneously in side and front views, the actions of a leg muscle and its myofibrils are shown while performing leg extension exercises.Launch animation

This animation highlights the individual bones and groups of bones that comprise the skeletal system.Launch animation

This animation illustrates some common skin conditions such as moles, birthmarks, age spots, and warts.Launch animation

This interactive animation takes you on a 3-D journey to explore the anatomy of the skull. Rotate the skull, see it in an exploded view, or pick from a list of terms to identify its various structures.Launch animation

This animation depicts the inhalation of air and scent molecules from a rose into an enlarged sagittal view of the nasal cavity. The smell receptors are magnified further to show their action of relaying a neural message of scent to the brain.Launch animation

Normal, healthy lungs are compared to the lungs of a long-term smoker.Launch animation

From a side view of the head and neck, this animation shows the structures involved in snoring. The common causes for snoring are also discussedLaunch animation

This animation highlights the structures of the male reproductive system and the pathway of ejaculate. A testicle is sectioned and enlarged to depict its internal anatomy, including a microscopic view of individual sperm.Launch animation

This animation highlights from a mid-sagittal view the structures of the male reproductive system and the pathway of ejaculate. A testicle is sectioned and enlarged to depict its internal anatomy, including a microscopic view of individual sperm.Launch animation

This animation shows a stomach ulcer forming and then reducing in size as it heals.Launch animation

This animation shows a stroke resulting by an embolism traveling from an internal carotid artery and lodging within a cerebral artery in the brainLaunch animation

This animations shows a piece of clot breaking away from the heart, travelling to the brain, resulting in a stroke.Launch animation

This animation enlarges a section of skin to illustrate melanocytes producing melanin in response to sun exposure. Also depicted on this enlarged section is sunburn and skin cancer.Launch animation

From a side view of the head, this animation shows the step-by-step process and mechanism of chewing and swallowing a piece of celery.Launch animation

This animation shows an enlargement of a section of skin to highlight an individual sweat gland. The gland then expels sweat onto the surface of skin.Launch animation

This animation shows a heart with tachycardia.Launch animation

This animation begins with a top view of the tongue then magnifies and shows two individual taste buds detecting taste molecules. The various taste centers (bitter, sour, sweet, and salty) are highlighted on the tongue.Launch animation

This animation discusses and depicts the role and function of the amniotic fluid surrounding a fetus.Launch animation

This animation shows the difference between a smoker's and non-smoker's arteryLaunch animation

This animation depicts Twin to Twin Transfusion Syndrome (TTTS) and the use of laser surgery to correct the condition.Launch animation

From an front view of the stomach, this animation shows the development of an ulcer in the stomach lining.Launch animation

This animation demonstrates how an ultrasound identifies the solid and hollow areas of structures within a fetus.Launch animation

This interactive animation enables you to visualize how a fetus may appear at 17, 19, and 30 weeks by enabling you to toggling a flat ultrasound image with an illustration of the baby's actual position.Launch animation

In a general overview, the formation and passage of urine through the various components of the urinary system is shown. Enlarged areas include the kidney, sectioned kidney, nephrons, renal corpuscle, and passage of particles and red blood cells within.Launch animation

In an enlarged view of a cut section of a small artery, this animation shows a vaccine injection and follows the path of its antigens, initiating the body's development of antibodies.Launch animation

This animation shows the process of a normal vaginal delivery.Launch animation

This animation shows a vasectomy procedure.Launch animation

Allergens like pollen are nothing more than foreign plant antigens. The stimulus for sneezing gets triggered when allergens first enter the nasal tissue. Pollen allergens encounter the plasma cells in the nose, which respond by producing antibodies. These antibodies attach to mast cells, which are white blood cells containing the chemical histamine. As more antibodies are produced, they cause the mast cells to release histamine. Histamine then produces allergy symptoms. A stuffy and runny nose, sneezing and watery eyes help to remove the invading pollen. Medications called antihistamines may be used to help alleviate severe allergy symptoms. In a person with Alzheimer's Disease, neurofibrillary tangles and plaques develop causing both structural and chemical problems in the brain. Alzheimer's disease appears to disconnect areas of the brain that normally work together.

An ankle sprain occurs when the joints ligament is stretched or torn. Ligaments are bands or sheets of regular, tough fibrous tissue that connect bones together. Symptoms of an ankle sprain include swelling and discoloration near the affected area. Ankle sprains may be classified as follows:

Type I sprain ligaments stretched

Type II sprain ligaments slightly torn

Type III sprain ligaments completely torn

Treatment for a Type I sprain should include rest, ice, compression and immobilization, and elevation of the affected area. This is easy to remember if you think of the acronym RICE. If you suspect a ligament is torn or completely severed, see your medical care professional for treatment.

A change in the heart's normal electrical conduction system can result in an arrhythmia or irregular heartbeat. An arrhythmia can be an abnormally slow heartbeat, or an abnormally fast heartbeat. In some cases, it can be fatal. Athetosis, or constant writhing movements, is often caused by injury to deeply situated structures with the brain called basal ganglia. Angioplasty is a procedure to open narrowed or blocked arteries caused by deposits of plaque. If the blockage is not major, the problem may be corrected by inflating the balloon several times to compact the plaque against the arterial wall, widening the passage for the blood to flow through. Typically, a device called a stent is placed within the coronary artery to keep the vessel open. When the bladder fills with urine, sensory nerves send impulses to the brain indicating that the bladder is full. The sensory nerves connect with other nerves in the spinal cord to relay this information. In turn, the brain sends impulses back to the bladder instructing the bladder to empty its contents.

The nervous system enables a person to blink to prevent harmful substances from getting in the eyes. During the normal course of a day, a person blinks an average of 15 times a minute to keep the eyes healthy. The lacrimal gland provides lubricating fluid for the eyes. The eyelid moves fluid from the lacrimal gland and across the eye. Blinking also provides the eyes with protection from foreign objects.

When the eye becomes irritated, the lacrimal gland produces extra tears to wash out impurities. Excess fluid drains through the tear ducts and into the nasal cavity. An abundance of tears draining through the nasal cavity may cause the nose to run and a person to sniffle.

The body contains a natural process to stop bleeding from minor cuts in a matter of several minutes. When a small artery is cut, the collagen fibers in its tissue are exposed, which signals clotting process to begin. As platelets begin to adhere to the cut edges, they release chemicals to attract even more platelets. Eventually a platelet plug is formed, and the external bleeding stops. Clotting factors in the blood cause strands of blood-borne material, called fibrin, to stick together and seal the inside of the wound. Eventually, the cut blood vessel heals, and the blood clot dissolves after several days. As the heart pumps, the arteries carry oxygen-rich blood (shown in red) away from the heart and toward the bodys tissues and vital organs. These include the brain, liver, kidneys, stomach, and muscles, including the heart muscle itself. At the same time, the veins carry oxygen-poor blood (shown in blue) from the tissues back toward the heart. From there, it passes to the lungs to receive more oxygen. This cycle repeats itself when oxygen-rich blood returns to the heart from the lungs, which pumps it throughout the body. Normal blood pressure is important for proper blood flow to the bodys organs and tissues. Blood pressure moves from high pressure near the heart to low pressure away from the heart. The force of the blood on the walls of the arteries is called blood pressure. Blood pressure is measured both as the heart contracts, which is called systole, and as it relaxes, which is called diastole. Normal blood pressure is considered to be a systolic blood pressure of 115 millimeters of mercury a diastolic pressure of 70 millimeters of mercury (stated as "115 over 70"). If an individual were to have a consistent blood pressure reading of 140 over 90, he would be evaluated for having high blood pressure. If left untreated, high blood pressure can damage important organs, such as the brain and kidneys as well as lead to a stroke. If a bone fracture is severe, a bone graft may be used to help speed the healing process. In this example, a metal plate is also used and fixated with screws. The plate and screws will be removed after the bone has healed.

After the animation loads, click and drag the model to rotate it in any direction. Select a term from the structure list to travel to its location.

Click the "pin" button to hide or show the identification pin.

Click the "light bulb" button to view in highlight or full color mode.

Click the "double box" button to see and rotate the model in transparent mode.

The brain is composed of more than a thousand million neurons. Specific groups of them, working in concert, provide us with the capacity to reason, to experience feelings, and to understand the world. They also give us the capacity to remember numerous pieces of information.

The 3 major components of the brain are the cerebrum, cerebellum, and brain stem.

The cerebrum is divided into is left and right hemispheres, each composed of a frontal, temporal, parietal, and occipital lobes. The cerebral cortex (gray matter) is the outside portion of the cerebrum and provides us with functions associated with conscious thought. The grooves and folds increase the cerebrums surface area, allowing us to have a tremendous amount of gray matter inside of the skull. Deep to the gray matter is the cerebral "white matter". The white matter provides for the communication between the cortex and lower central nervous system centers.

The cerebellum is located near the base of the head. It creates automatic programs so we can make complex movements without thinking.

The brain stem connects the brain with the spinal cord and is composed of 3 structures: the midbrain, pons, and medulla oblongata. The brain stem provides us with automatic functions that are necessary for survival.

In a breast lift or breast reduction procedure, incisions are made to accommodate a higher position for the areola and nipple, as well as to remove excess skin and breast tissue. Stitches usually follow the circumference of the areola, the natural lower crease of the breast, and a vertical line extending between the areola and lower crease.

The two lungs are the primary organs of the respiratory system. Other components of the respiratory system conduct air to the lungs, such as the trachea (windpipe) which branches into smaller structures called bronchi.

The process of breathing (respiration) is divided into two distinct phases, inspiration (inhalation) and expiration (exhalation). During inspiration, the diaphragm contracts and pulls downward while the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. As a result, air rushes in and fills the lungs.

During expiration, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.

Bunions are usually caused by prolonged pressure put on the feet that compresses the big toe and pushes it toward the second toe. Over time, the condition may become painful as extra bone grows where the base of the big toe meets the foot. Malignant tumors of the vocal cords are typically caused by tobacco use. The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components of the cardiac conduction system are the SA node, AV node, bundle of HIS, bundle branches, and Purkinje fibers. The SA node (anatomical pacemaker) starts the sequence by causing the atrial muscles to contract. From there, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an Electrocardiogram (EKG or ECG). Doctors use an EKG to monitor the cardiac conduction systems electrical activity in the heart. In this case of cardiomyopathy, part of the septum dividing the ventricles, is interfering with the normal emptying of the left ventricle. This is one variety of the condition called hypertrophic obstructive cardiomyopathy (HOCM). A catheter is introduced into the heart and through it, concentrated alcohol is applied to the abnormal area, shrinking it, allowing the heart to function normally. The cardiovascular system is composed of the heart and the network of arteries, veins, and capillaries that transport blood throughout the body. The average adult male has between 5 to 6 liters of blood or blood volume, while the average adult female has between 4 to 5 liters. The blood carries oxygen and essential nutrients to all of the living cells in the body, and also carries waste products from the tissues to the systems of the body through which they are eliminated.

Most of the blood is made up of a watery, protein-laden fluid called plasma. A little less than half of this blood volume is composed of red and white blood cells, and other solid elements called platelets. Cataracts may develop with advancing age or in response to diseases such as diabetes. A cataract appears as a cloudy area in the lens. During the first 12 hours after conception, the fertilized egg cell remains a single cell. After approximately 30 hours, it divides from 1 cell into 2 and 15 hours later, the 2 cells divide into 4. And at the end of 3 days, the fertilized egg cell has become a berry-like structure made up of 16 cells. This structure is called a morula, which is Latin for mulberry.

The cells continue to divide 8 or 9 days following conception into a blastocyst. Although it is only the size of a pinhead, the blastocyst is composed of hundreds of cells. The blastocyst is slowly carried by tiny hair-like projections in the fallopian tube called cilia toward the uterus. During the critically important process of implantation, it must attach itself to the uterine lining where it will be able to get nourishment from the mothers blood supply. If the blastocyst is unable to attach, the pregnancy will fail to survive. The tissue of the brain is supplied by a network of cerebral arteries. If the wall of a cerebral artery becomes weakened, a portion of the wall may balloon out forming an aneurysm. A cerebral aneurysm may enlarge until is bursts, sending blood throughout the spaces in or surrounding the brain. Click and drag the slider bar to see the various stages of cervical dilation between 0 and 10 cm. Although Cesarean (C-sections) are relatively safe surgical procedures, they should only be performed in appropriate medical circumstances. Some of the most common reasons for a Cesarean are:

If the baby is in a feet first (breech) position If the baby is in a shoulder first (transverse) position If the babys head is too large to fit through the birth canal If labor is prolonged and the mothers cervix will not dilate to 10 centimeters If the mother has placenta previa, where the placenta is blocking the birth canal If there are signs of fetal distress which is when the fetus is in danger because of decreased oxygen flow to the fetus

Some common causes of fetal distress are: Compression of the umbilical cord Compression of major blood vessels in the mothers abdomen because of her birthing position Maternal illness due to hypertension, anemia, or heart disease

Like many surgical procedures, Cesarean sections require anesthesia. Usually, the mother is given an epidural or a spinal block. Both of these will numb the lower body, but the mother will remain awake. If the baby has to be delivered quickly, as in an emergency, the mother may be given a general anesthetic, which will make her fall asleep.

During the surgery, an incision is made in the lower abdomen followed by an incision made in the uterus. There is no pain associated with either of these incisions because of the anesthesia. Once the uterus is open, the doctor will let the amniotic fluid drain from the amniotic sac. Then the baby is carefully eased through the incision and out into the world. The procedure usually lasts about ten minutes.

Afterward, the physician delivers the placenta and stitches up the incisions in the uterus and abdominal wall. Usually, the mother is allowed to leave the hospital within a week, barring complications. Skin is the bodys largest organ. About six pounds of skin cover eighteen square feet on an average adult.

The top layer of skin is called the epidermis. It protects the underlying skin layers from the outside environment and contains cells that make keratin, a substance that waterproofs and strengthens the skin. The epidermis also has cells that contain melanin, the dark pigment that gives skin its color. Other cells in the epidermis allow us to feel the sensation of touch and provide the body with immunity against foreign invaders like germs and bacteria.

The very bottom layer of the skin is the hypodermis. It contains the fat cells, or adipose tissue, that insulate the body and help it conserve heat. The layer between the epidermis and the hypodermis is the dermis. It contains the cells that give skin strength, support, and flexibility. As a person ages, the cells in the dermis lose their strength and flexibility, causing the skin to lose its youthful appearance.

Located in the dermis are sensory receptors. They allow the body to receive stimulation from the outside environment and experience pressure, pain, and temperature. Small blood vessels provide the skin with nutrients, and remove its waste products.

Sebaceous glands produce the oil in the skin, which keeps it from drying out. The oil from the sebaceous glands also helps to soften hair and kill bacteria that get in the skins pores. These oil glands are all over the body, except on the palms of the hands and the soles of the feet.

During intercourse, sperm are released into the vagina near the cervix, swim through the uterus and travel up the fallopian tubes. Sperm are composed of 3 parts: a head, a middle section, and a tail. The tail propels the sperm, which is powered by energy cells stored in the middle section. The head of the sperm contains the mans genetic material and an enzyme-filled acrosomal cap needed to help the sperm penetrate through the outer membrane of the egg.

As an egg released by an ovary travels through a fallopian tube, it may encounter hundreds of sperm that have survived to reach this point in their journey. Eventually, one sperm may succeed in breaking through the eggs outer membrane.

After penetrating the eggs outer membrane, the sperm releases its nucleus, which unites with the nucleus from the egg. Fertilization or conception occurs when the sperm fuses with the egg to form a fertilized egg (zygote).

Click a circle in the "Navigation" box to travel to a particular section of the female reproductive system. At each section, select the "Click here to play animation" to see an action occur that leads to the successful conception of a fertilized egg. During sexual intercourse, sperm are released into the vagina near the cervix, which is the entrance to the uterus. The sperm travel through the cervix, into uterus and up the fallopian tubes.

After being release from an ovary, the egg cell moves through the fallopian tube by tiny cilia that line the tubes walls. The egg cell only survives for approximately 24 hours after ovulation. Of the millions of sperm that are released into the naturally acid environment of the womans reproductive tract, relatively few will survive to encounter the egg cell.

When one of the sperm cells finally succeeds in breaking through the egg cell's outer membrane, the egg cell forms a protective barrier preventing other sperm cells from entering. This ensures that only one sperm cell fertilizes the egg cell.

Next, the sperm cell releases its nucleus containing the mans chromosomes. After several hours, it unites with the nucleus of the egg cell, which contains the womans chromosomes. When the two nuclei fuse, their genetic material combines together to create a fertilized egg cell which is called a zygote. Millions of sperm are released during a single ejaculation. Their tails propel on their journey to encounter the single egg cell. Of the millions of sperm, only a few will survive to reach the egg and just one will penetrate the egg cells wall to combine its genetic material with that of the egg in the process called fertilization. If during the first week of cell division, the fertilized egg cell, or zygote, divides into 2 zygotes, identical twins will form. Each developing embryo contains the same genetic material as the other. In a severe impact to the head, the brain moves and hits the skull causing injury. During a boxing match, the brain moves from side to side after the impact of a punch. Following a concussion head injury, confusion and disorientation due to temporary distortion of the brain may result. Injury or infection of the cornea, the transparent front window of the eye, can lead to serious visual impairment.

Coronary artery bypass graft surgery (CABG) is an invasive procedure that involves taking a section of vein from the leg and grafting it onto a location on the heart, which allows blood to bypass the blocked portion of the coronary artery.

The procedure begins with the surgeon making a cut in the leg and removing a section of vein. Both ends of the vein are tied-off in the leg and cut is closed. The chest is opened and the blood is rerouted through a heart-lung machine. The heart is then stopped.

The surgeon locates the blocked coronary artery and attaches the section of vein taken from the leg to the aorta and to the coronary artery below the blocked segment of the artery. The surgeon may do as many bypasses on as many blocked coronary arteries as the patient needs.

Once each bypass graft is placed, it is checked for leaks. Following this, the heart is restarted. Once the heart is beating again, the surgeon will remove its attachments to the heart-lung machine and sew the openings closed. Following this the chest is closed. A pacemaker may be inserted during the procedure to help control any heart rhythm problems the patient may have.

The coronary arteries supply blood to the heart muscle itself. Damage to or blockage of a coronary artery can result in injury to the heart. Normally, blood flows through a coronary artery unimpeded. However, if the inner wall of a coronary artery becomes damaged, cholesterol plaque can build-up, progressively narrowing the available pathway through which blood can flow.

Clotted blood attempting to traverse the blood vessel may find it tortuous and too narrow for passage, and the artery may become completely constricted or blocked-off. The blocked artery results in a lack of oxygen, or ischemia, to the part of the heart muscle that the artery supplies. The result is a heart attack. Facial cosmetic surgery may include a forehead lift. In this procedure, a hairline incision is made, the forehead skin is pulled-up and excess skin tissue is removed. In an eyelid lift (blepharoplasty), creases and wrinkles around the eyes can be minimized by removing excess fat and skin from the upper and lower eyelids. A facelift usually consists of an incision along or above the hairline and in front of the ears. Excess fat and skin is removed and facial muscles may be tightened.

Coughing is a sudden expulsion of air from the lungs through the epiglottis at an amazingly fast speed (estimated at 100 miles per hour). With such a strong force of air, coughing is the bodys mechanism for clearing the breathing passageways of unwanted irritants.

In order for a cough to occur, several events need to take place in sequence. First, the vocal cords open widely, allowing additional air to pass through into the lungs. Then the epiglottis closes off the windpipe (larynx), and simultaneously, the abdominal and rib muscles contract, increasing the pressure behind the epiglottis. With the increased pressure, the air is forcefully expelled, and creates a rushing sound as it moves very quickly past the vocal cords. The rushing air dislodges the irritant, making it possible to breathe comfortably again.

Diabetes may affect the retina by causing the formation of whitish patches called exudates. Other indications may include tiny enlargements of the blood vessels resulting in microaneurysms and hemorrhages.

Digestion is the process in which food is broken down into nutrients used by the body. Food passes from the mouth through the esophagus to the stomach. The stomach churns the food and breaks it down further with its contents of hydrochloric acid and an enzyme called pepsin.

The process of breaking food down in the stomach takes a few hours. From there, it goes to the duodenum where it is broken down further by digestive bile produced by the liver and stored in the gallbladder along with enzymes from the pancreas. Enzymes are chemicals that speed up the digestion of specific types of food. For example, the enzyme trypsin breaks down the protein in steak, lipase helps to break down fat, and lactase breaks down the sugar in milk.

Once everything is broken down, the small intestine absorbs the nutrients the body needs. From there the nutrients go into the bloodstream and to the liver, where poisons are removed. Undigested food and water continue through the small intestine and go into the large intestine, where water is reabsorbed. Finally, feces are eliminated through the rectum and anus.

Directional Coronary Atherectomy (DCA) is a minimally invasive procedure to remove the blockage from the coronary arteries and allow more blood to flow to the heart muscle and ease the pain caused by blockages.

The procedure begins with the doctor injecting some local anesthesia into the groin area and putting a needle into the femoral artery, the blood vessel that runs down the leg. A guide wire is placed through the needle and the needle is removed. An introducer is then placed over the guide wire, after which the wire is removed. A different sized guide wire is put in its place.

Next, a long narrow tube called a diagnostic catheter is advanced through the introducer over the guide wire, into the blood vessel. This catheter is then guided to the aorta and the guide wire is removed. Once the catheter is placed in the opening or ostium of one the coronary arteries, the doctor injects dye and takes an x-ray.

If a treatable blockage is noted, the first catheter is exchanged for a guiding catheter. Once the guiding catheter is in place, a guide wire is advanced across the blockage, then a catheter designed for lesion cutting is advanced across the blockage site. A low-pressure balloon, which is attached to the catheter adjacent to the cutter, is inflated such that the lesion material is exposed to the cutter.

The cutter spins, cutting away pieces of the blockage. These lesion pieces are stored in a section of the catheter called a nosecone, and removed after the intervention is complete. Together with rotation of the catheter, the balloon can be deflated and re-inflated to cut the blockage in any direction, allowing for uniform debulking.

A device called a stent may be placed within the coronary artery to keep the vessel open. After the intervention is completed the doctor injects contrast media and takes an x-ray to check for any change in the arteries. Following this, the catheter is removed and the procedure is completed.

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After the membranes rupture and the water breaks, a woman may begin to experience the first phase of labor (early labor). The average time of early labor is extremely variable, lasting anywhere from 2 to 6 hours. In rare cases, it can last up to 24 hours.

During this time, the pressure of repeated regular contractions causes the cervix, which had been closed when labor began, to open up to a diameter of 3 centimeters while becoming much thinner.

Various techniques can be used to help alleviate the discomfort a woman may experience during the first phase of labor such as back-rubs and breathing exercises. All of the immature egg cells (oocytes) a woman will ever produce are stored in the ovaries by the time she is born. The average age that girls begin to menstruate is 12 years old. Each menstrual cycle occurs approximately every 28 days. During each cycle, hormonal messages from the brain cause the ovaries to develop a single mature egg cell for potential fertilization, even as other hormones instruct the uterine lining to thicken in preparation for nourishing the fertilized egg cell.

The cycle starts when a follicle grows within one of the ovaries. A follicle is composed of the developing egg cell and the support cells that surround and nourish it. On day 1 of the cycle, a small structure in the brain, the pituitary gland, releases two hormones, FSH and LH, both of which cause the follicle to begin growing.

Over the next 13 days, the growing follicle releases estrogen, a hormone that prepares the lining of the uterus to receive a fertilized egg cell. Meanwhile, the estrogen in the bloodstream causes the brain to release a surge of LH. In response to the LH surge, the follicle enlarges rapidly. On day 14, it ruptures and releases the egg cell in a process known as ovulation.

The ruptured follicle begins secreting the hormone progesterone, which also helps to prepare the uterine lining for a fertilized egg cell. The egg cell is swept into the fallopian tube entrance by its waving structures called fimbriae.

Once the egg cell is within the fallopian tube, it will either be fertilized by a sperm cell, or fertilization will fail to take place. If the egg cell is not fertilized within 24 hours after its release from the ovary, it will stop developing and will dissolve before reaching the uterus. The absence of a fertilized egg cell gradually causes a womans body to stop releasing the hormones that would otherwise prepare the uterus for the developing egg cell. In response, the uterus sheds its lining on days 24 through 28 during menstruation.

If a sperm does fertilize the egg cell, tiny hair-like cells called cilia will transport it towards the uterus. The fertilized egg now called a blastocyst, lodges in the uterine wall in a process called implantation to receive nourishment from the uterine lining. The remaining cells of the ruptured follicle in the ovary produce progesterone so that the uterine lining will stay rich in blood vessels, and the fertilized egg cell will survive.

A woman is born with all of the egg cells she will release throughout her lifetime. Starting at about age 12 through menopause, a womans reproductive cycle releases an egg about once a month.

Hormonal messages from the brain instruct the ovaries to develop several follicles in which a single dominant follicle in one of the ovaries will release an egg for fertilization. During this time, other hormones instruct the uterine lining to thicken in preparation for nourishing a fertilized egg.

There are several hormones that regulate the reproductive cycle. Follicle stimulating hormone (FSH) stimulates preparation of the egg for fertilization by instructing a follicle to begin dividing its genetic material (chromosomes).

The follicle then releases estrogen, the hormone that prepares the lining of the uterus to receive a fertilized egg. Increased levels of estrogen in the bloodstream cause a small structure in the brain, the pituitary gland, to stop releasing the hormone FSH, and to start releasing luteinizing hormone (LH).

LH causes the follicle to enlarge rapidly and to release its egg in a process known as ovulation. Once the egg is out of the follicle, the follicle begins secreting the hormone progesterone, which also helps to prepare the uterine lining for the fertilized egg. The remaining cells of the follicle shrink into a hormone producing mass of cells called a corpus luteum.

The egg is swept into the fallopian tube by its waving structures called fimbriae. Fertilization of the egg usually occurs in the fallopian tube. From there, it is transported to the uterus and implants itself in the uterine wall, where it is nourished by the uterine lining. In the ovary, the corpus luteum produces progesterone so that the egg can develop into a fetus.

If the egg is not fertilized within 24 hours after its release from the ovary, it stops developing and dissolves before reaching the uterus. The absence of a fertilized egg causes the body to stop releasing the hormones that prepare the uterus for implantation. In response, the uterus sheds its lining over a period of four to five days in a process known as menstruation.

Click the waveform pull-down list to view various waveforms showing normal and pathological conditions of the heart. The endocrine system is primarily composed of glands that produce chemical messengers called hormones. Glands of the endocrine system include the pituitary gland, the thyroid gland, the parathyroid glands, the thymus, and the adrenal glands. Other glands are also included within the endocrine system since they contain endocrine tissue that secretes hormones such as the pancreas, ovaries and testes.

The endocrine and nervous systems work very closely together. The brain continuously sends instructions to the endocrine system, and in return receives feedback from the endocrine glands. Because of this intimate relationship, the nervous and endocrine systems are referred to as the neuroendocrine system.

The hypothalamus is known as the master switchboard because its the part of the brain that controls the endocrine system. The pituitary gland, which hangs by a thin stalk from the hypothalamus, is called the master gland of the body because it regulates the activity of the endocrine glands.

The hypothalamus detects the rising level of the target organs hormones then sends either hormonal or electrical messages to the pituitary gland. In response, the pituitary gland releases hormones, which travel through the bloodstream to a target endocrine gland, instructing it to stop producing its hormones.

The endocrine system constantly adjusts hormone levels so that the body can function normally. This process is called homeostasis. The prostate gland is located underneath the bladder and is about the size of a chestnut. Part of the urethra is encased within the prostate gland. As a man ages, the prostate typically enlarges in size in a process called benign hypertrophy (non-cancerous enlargement).

The enlarged prostate crowds its surrounding structures and may cause the urethra to narrow. The narrowed urethra results in several of the symptoms of benign prostatic hypertrophy (BPH). Symptoms may include a slowed or delayed start in urination, the need to urinate frequently during the night, difficulty in emptying the bladder, a strong, sudden urge to urinate, and incontinence. Less than half of all men with BPH have symptoms of the disease, or their symptoms are minor and do not restrict their life style.

BPH is a normal physiological process of aging and treatment options are available. The choice of the appropriate treatment is based on the severity of the symptoms, the extent to which they effect lifestyle, and the presence of other medical conditions. Men with BPH should consult with their physician yearly to monitor the progression of the symptoms and decide the best course of treatment as needed. The prostate gland is located underneath the bladder and is about the size of a chestnut. Part of the urethra is encased within the prostate gland. As a man ages, the prostate typically enlarges in size in a process called benign hypertrophy (non-cancerous enlargement).
The enlarged prostate crowds its surrounding structures and may cause the urethra to narrow. The narrowed urethra results in several of the symptoms of benign prostatic hypertrophy (BPH). Symptoms may include a slowed or delayed start in urination, the need to urinate frequently during the night, difficulty in emptying the bladder, a strong, sudden urge to urinate, and incontinence. Less than half of all men with BPH have symptoms of the disease, or their symptoms are minor and do not restrict their life style.
BPH is a normal physiological process of aging and treatment options are available. The choice of the appropriate treatment is based on the severity of the symptoms, the extent to which they effect lifestyle, and the presence of other medical conditions. Men with BPH should consult with their physician yearly to monitor the progression of the symptoms and decide the best course of treatment as needed. During periods of stress, such as preparing to run in a race, the brain signals the adrenal glands to produce epinephrine or "adrenaline". Epinephrine increases the rate in which the heart beats. The increased cardiac output supplies more oxygen to the muscles, putting the body a heightened state to react. As a longer term response to stress, cortisol is secreted by the adrenal glands, promoting the release of energy. Weight lifting is a form of anaerobic exercise. It is very demanding, requiring a great deal of energy, which quickly depletes the bodys oxygen reserves. Sprinting and push-ups are other examples of anaerobic activities. They each create a situation called oxygen debt, which requires us to breathe deeply and rapidly in order to restore a proper oxygen level to the muscle cells.

If oxygen reserves become depleted while exercising, muscles convert a starch, called glycogen, into energy. This conversion process creates a waste product called lactic acid, which can be partly responsible for muscle soreness the next day.

Jogging is a form of aerobic exercise. Exercising over a long duration requires a steady level of energy for the body. If properly conditioned, the body will be able to supply adequate oxygen to meet its energy requirements during aerobic exercise and much less lac