The Human Body
The Main Organs Of The Human Body - Explained

Health Topics

The Human Body


Trachea (Windpipe)
Small Intestines
Large Intestines


Location: Internal: Inside the skull.
Function: Controls all the other organs of the body and ensures they work together as a team.

What Can Go Wrong (Lots!)
Strokes: Brain attack, blood flow to the brain is restricted.
Mini-Stroke: A 'small' stroke, can indicate something bigger is brewing.
Hemorrhage: Bleeding in the brain, most common cause is stroke.
Aneurysm: Blood vessel in the brain bursts, causing internal bleeding.
Alzheimer's Disease: Causes confusion, loss of memory and speech problems.
Tumor: Cancer which starts in the brain or spreads from another part of the body.
Amnesia: Loss of memory, usually after a traumatic event.
Concussion: Injury to the head, causes loss of consciousness. Never let a concussed person fall asleep.
Epilepsy: Electrical activity of the brain is briefly interrupted resulting in a seizure.
Chemical Imbalance: Causes various types of depression. Effects of depression.
Headaches: From stress headaches to migraines.
Head And Face Disorders: Symptom checker.

The brain is where our consciousness is located, it allows us to think, learn and create. Information is primarily passed to and from the brain to the rest of the body, along the nerves of the spinal cord. The brain is divided into 4 main areas: the cerebrum, cerebellum, diencephalon and brain stem.
(1) Cerebrum: This is the largest part of the brain. It is split into two halves called hemispheres. The left hemisphere is used for analytical thinking and the right hemisphere helps us look at situations as a whole and make emotional judgments. The main parts of the cerebrum are:
Frontal lobe: Controls mood, muscle movement, planning for the future, setting goals and juggling priorities.
Parietal lobe: Processes information about temperature, touch, taste and movement coming from other parts of the body. Maths and reading are also processed here.
Pons: Important center for controlling breathing and cardiovascular function. It also helps to coordinate eye movement and balance.
Occipital lobe: Processes visual information for sight.
Temporal lobe: Processes memory, language and hearing.
(2) Cerebellum: This is the second biggest part of the brain. It coordinates muscles, allowing precise movements, balance and posture.
(3) Diencephalon: Contains the thalamus and hypothalamus. The thalamus is highly sensitive to incoming information, it lets the brain know what is happening outside of the body.The hypothalamus keeps conditions in the body regular. It regulates signals of thirst, hunger and body temperate. It also controls the release of hormones (little messengers) from the pituitary gland.
(4) Brain stem: Critical for regulating your heart beat, digestion, breathing and blood pressure - all unconscious activities that you are not aware of.
The brain is encased in three layers of membranes called meninges. Between each layer is a clear fluid which cushions the brain and helps protect it from infection.
Can I Live Without It?
No, without a brain, we die instantly. Furthermore any injury to the brain is permanent - despite medical advances doctors have not found a cure for brain damage. Once cells in the brain die, we permanently lose the function they are responsible for.

Location: Runs down the neck, connects the voice box to the lungs.
Function: Also known as the windpipe, it allows the passage of air into the lungs.

Things That Can Go Wrong
Choking: Food or another object becomes lodged in the windpipe. Can be deadly.
Tracheitis: Inflammation of the lining of the windpipe.
The trachea is made of cartilage and ligaments. It connects the voice box (larynx) to the lungs where it branches into the right and left lung. It measures about 10 to 12 cm. It is an important part of the respiratory system, allowing air to flow in and out of the lungs. Any damage to the windpipe is potentially life-threatening. If the windpipe becomes blocked it may be necessary to cut a whole in it and to insert a tube to provide ventilation (tracheostomy).
Can I Live Without It?
Yes, although surgeons will need to insert a permanent tube via tracheostomy to ensure breathing is possible.


Location: Inside the ribcage.
Function: To feed oxygen into our blood supply and to remove carbon dioxide.

Things That Can Go Wrong
Lung cancer: Top-killing cancer, see causes of death in women.
Asthma: Airway constricts leading to breathing difficulties.
Pulmonary embolus: Blood clot that blocks the blood vessels in the lungs. Can cause sudden death.
Chronic bronchitis: Airways of the lungs become thickened which limits airflow.
Emphysema: Lung tissue breaks down causing difficulties in oxygen passing into the blood.
Influenza: Respiratory infection that is caused by a virus.
Pneumonia: Severe inflammation of the lungs, causes fluid buildup so the person can't breath.
Pleurisy: Inflammation of the lining of the lungs, causes pain when you breathe in.
Chest Problems: Symptom checker.
The lungs are a pair of spongy organs located inside the chest. They are the main part of ourĀ respiratory system. Their function is to deliver oxygen into the blood and to remove carbon dioxide from it. When we breathe in, air rushes through our nose or mouth, down the windpipe (trachea) and into the lungs. Once in the lungs the air eventually passes into tiny bubbles called alveoli. The alveoli are covered with equally tiny blood vessels one cell thick. Oxygen seeps from the alveoli into these vessels and the blood supply, and carbon dioxide waste seeps back from the blood for removal when we breathe out.
Can I Live Without Them?
It is possible to live with one lung, although your physical activity will be severely restricted. It is not possible to live without both lungs. If both lungs are removed because of cancer (thoracotomy), survival will depend on receiving a lung transplant.
Location: Between the lungs, slightly to the left side of the chest.
Function: To pump oxygenated blood around the body and to return un-oxygenated blood to the lungs.

Things That Can Go Wrong
Heart Disease: Conditions which affects the heart's function.
Coronary Heart Disease: Disease of the heart's arteries.
Heart Attack: Blood to the heart is suddenly blocked.
Irregular Heartbeat: Heart arrhythmia and palpitations.
Congestive Heart Failure: When the heart gradually fails.
High Blood Pressure: One of the main causes of heart problems.
Chest Pain: There are numerous causes of chest pain.
Angina Attacks: Strangling pain in the chest.
The heart is located slightly to the left side of your chest. It is a powerful organ made of cardiac muscle. Unlike other muscle in the body, it never tires. Its function is to pump blood around the body, and to do this is contracts and relaxes about 70 times a minute. Blood is a liquid that carries oxygen and food supplies to the cells of the body and takes waste and carbon dioxide away. It also distributes hormones and chemicals. Blood is transported around the body by a network of 100,000 km's of veins and smaller veins called capillaries. Yet it only takes less than 90 seconds for blood to circulate through this entire system. The system itself is called the cardiovascular or circulatory system. The heart is supplied with blood by the coronary arteries. If they become clogged with fat overtime blood flow will be restricted and a heart attack can occur (how a heart attack happens). Alternatively the heart can develop a mechanical fault which gradually weakens its pumping ability; this is known as congestive heart failure.
Can I Live Without It?
No, the heart is a vital organ. If the heart suddenly stops pumping, the person will die within seconds (sudden cardiac arrest). To assist in this situation read about hands only CPR. In other heart failure situations doctors can insert an artificial pump (ventricular assist device) to keep blood flowing, but this is only a temporary measure for people waiting for a heart transplant.
Related Questions
What is blood?
Location: Under the diaphragm, slightly to the right side of the body.
Function: To rid toxins from the blood, to control blood sugar and produce bile for digestion purposes.

Things That Can Go Wrong
Cirrhosis: Liver damage usually caused by either longterm alcohol abuse or hepatitis C.
Wilson's Disease: Genetic disorder where too much copper in the body damages the liver.

The liver is a vital organ, not only for its role in the digestive system, but for the work is does throughout the body. It is located on the right side of the tummy, just below the diaphragm. Its role is to regulate, convert, store and process countless substances that we eat, breathe in and absorb through the skin. At any one time the liver is filtering and correcting 13 percent of the body's entire blood supply. It takes out poisonous substances like alcohol, toxins, bacteria and air pollution. Any waste products are either then sent to the intestines for removal as feces or to the liver for further filtering and removing through urine. It also stores excess vitamins and produces about 80 percent of our natural supply of cholesterol.
Can I Live Without It?
No, if your liver failed you would die within 24 hours. A common sign of liver failure is jaundice where the whites of your eyes and skin turn yellow. If the liver fails, we die (unless a liver transplant is viable). Even liver dialysis can only be used short term.

Location: Above the small intestine, left side of the body.
Function: It stores food and gradually breaks it down by mixing it with gastric juices. It then squirts the remaining liquid into the small intestines.

What Can Go Wrong:
Indigestion and heartburn are the most common problems.
Gastric ulcers.
Gastroesophageal reflux disease (GERD).
Stomach cancer, although this is relatively rare.
An adult stomach can expand to store up to 3 liters of food. Food enters the stomach via the esophagus tube. Once in the stomach it is prevented from passing back into the esophagus by a small circular muscle called the cardiac sphincter. Occasionally the sphincter fails to work and stomach juices pass into the esophagus causing a sensation of heart burn. The stomach acts as a short-term storage facility which allows you to eat a large meal quickly but to break it down gradually over a number of hours. The stomach lining releases enzymes and hydrochloric acid to start the process of breaking food down. The acid kills any bacteria to prevent it causing any damage. The stomach protects itself from the effects of the acid by secreting a mucus that clings to the stomach walls. If this lining becomes damaged, it can result in painful stomach ulcers. The muscles in the wall of the stomach also assist by contracting (peristalsis) reducing food to a thick creamy mush. Gradually the liquid is squirted into the small intestines where the digestion process continues. In all, food spends about 4 and 6 hours being reduced in the stomach.
Can I Live Without It?
Yes, some people have their stomach removed (gastrectomy) to treat advanced cases of stomach cancer. Without a stomach, food passes directly from the esophagus into the intestines (Roux-en-Y reconstruction). Over time the body compensates; a small pouch develops in the small intestine which means food can be stored a little longer before being pushed on its way. The person usually needs to eat smaller portion sizes and may experience pain from time to time, but they can continue to live a relatively normal life.

Location: Left side of the body, near the stomach. It is about as big as your fist.
Function: Cleans the blood, destroys old red blood cells and fights infections.

What Can Go Wrong
Rupture: The spleen can be damaged by injury causing it to rupture.
Enlarge: It can become enlarged (splenomegaly) and rupture.

The spleen is part of the lymphatic system which keeps your body fluids in balance and fights infection. The spleen filters blood which flows through it, cleansing it of bacteria, viruses and other unwanted substances. It contains white blood cells (called macrophages) which surround and destroy dead tissue, foreign matter and bacteria. This helps to keep the blood 'clean' and protects the body from infection. It also destroys old or damaged red blood cells (which have an average life span of 120 days). They are then transported to another part of the body for either excretion or recycling to make new cells.
What Can Go Wrong
The spleen can be damaged by injury or it can become enlarged (splenomegaly) and rupture. Splenomegaly can cause the spleen to enlarge several times it normal size. Symptoms include fatigue, weakness and referred pain in the left shoulder. It can cause a loss of appetite and a sense of fullness after eating very little. Splenomegaly can be caused by viral and bacterial infections (such as mononucleosis), rheumatoid arthritis, leukemia and sickle cell anemia. If the spleen ruptures you will need immediate surgery to control the bleeding.
Can I Live Without It?
Yes, it is possible to live without your spleen because other parts of the body will take over its function. However you will find it more difficult to fight infections.

Location: Top of the small intestines.
Function: To secrete digestive enzymes to aid digestion and hormones to control blood sugar levels.

What Can Go Wrong:
Type 1 Diabetes: Pancreas no longer produce insulin.
Type 2 Diabetes: The pancreas loses it's ability to secrete enough insulin.
Pancreatitis: Inflammation of the pancreas.
Cystic fibrosis: A genetic disorder.
Pancreatic cancer: Fourth leading cause of cancer deaths in the U.S.
When you eat, the pancreas secretes digestive juices into the first part of the small intestines called the duodenum. These juices aid the digestion process by breaking down protein, fats and carbohydrates. They also contain sodium bicarbonate which neutralizes the acid coming from the stomach. Another important role of the pancreas is to control levels of sugar in the blood. It does this by secreting 3 substances: (1) insulin, which stimulates cells to use sugar (glucose), thus lowering sugar levels and (2) glucagon- has the opposite effect and triggers cells to release glucose, increasing blood sugar levels. It acts as a control mechanism for the body produces too much insulin and (3) somatostatin, which appears to regulate insulin and glucagon.
What Can Go Wrong
As the pancreas is embedded so deep in the body, it can be difficult to diagnose when things go wrong with it. The most common conditions linked to it are:
Type 1 Diabetes: The cells of the pancreas no longer produce insulin because they have been attacked by the body's immune system.
Type 2 Diabetes: The pancreas loses it's ability to secrete enough insulin.
Pancreatitis: Inflammation of the pancreas where the pancreatic enzymes start digesting the pancreas itself. Alcohol abuse or gallstones can cause this problem.
Cystic fibrosis: A genetic disorder which cause the pancreas tubes to become blocked with a sticky mucus.
Pancreatic cancer: Fourth leading cause of cancer deaths in the U.S.
Can I live Without It?
Yes it is possible to live without the pancreas, but you will need to take insulin daily as well as pancreatic enzyme supplements to help digestion.

Location: Sits just under the liver.
Function: Stores bile produced by the liver. Bile is a liquid which helps the body digest fats.

What Can Go Wrong
Gallstones: Small painful stones form in the gallbladder.
Pancreatitis: Gallstones block the ducts that drain the pancreas.
Gallbladder Cancer: Relatively rare.
The gallbladder's role is to collect bile produced by the liver and store it until needed. Bile is a yellow-green fluid and the liver produces about 1 liter of it a day. Once it arrives for storage in the gallbladder the water is removed concentrating the liquid. Before eating your gallbladder expands to the size of a small pear. After eating it contracts, squeezing bile into the small intestines to break down fat in the food we eat. When all the bile has been excreted the gallbladder looks flat and deflated.
What Can Go Wrong
Most problems occur as a result of the presence of gallstones (cholelithiasis). These are small stones which form when cholesterol, one of the ingredients of bile, hardens into a crystal-type material. While usually harmless, gallstones can be painful and cause nausea. If the gallbladder becomes inflamed (due to gallstones), you may develop severe pain and fever (cholecystitis); this can require surgery if it recurs. If the gallstones block the ducts that drain the pancreas, the pancreas can become inflamed. This dangerous condition is called gallstone pancreatitis and needs immediate care. Gallbladder cancer is relatively rare and is normally only diagnosed at a late stage because symptoms are similar to gallstones.
Can I Live Without It?
Yes, removal of the gallbladder (cholecystectomy) will not have any signficant impact on your life. The bile duct will be redirected to secrete bile directly into the small intestine, instead of being stored in the pancreas. There is a slight risk of diarrhea (as bile is being continually fed into the intestines) and fat malabsorption (problems breaking down and absorbing fats in your food); but this can normally be sorted with medications.

Location: At the bottom of the ribcage, towards the back of the body.
Function: To clean the blood and make urine from the waste products. Note: Kidney function is sometimes referred to as 'renal function'. It means the same thing.

What Can Go Wrong
Kidney Failure: Can happen suddenly (due to trauma) or over the longterm due to medical conditions like diabetes or high blood pressure.

The kidneys are a pair of bean-shaped organs located in the small of the back. Their role is to clean the blood and keep the level of water in the body under control. They draw water and other substances from the blood and dispel any waste products through urine. They work cleverly, only taking unnecessary water out of the body. So if you drink a lot of liquids, you will urinate a lot, this is to stop too much water swishing around the cells and bloating. If you don't drink much, you will produce your kidneys will produce less and more concentrated urine. Urine runs from each kidney down a tube called a urethra and into the bladder. When the bladder is full you will feel the urge to urinate. All blood in the body flows through the kidneys every 10 minutes, so your blood is filtered 150 times a day. Your kidneys also have a role in regulating blood pressure. If blood pressure drops, they secrete an enzyme called renin. Renin triggers a chain of biological events that cause the kidneys to absorb more water and salt, thus raising blood pressure.
What Can Go Wrong
Most renal (kidney) failure takes years to happen, it is not normally an overnight problem. Common condition which damage the kidneys include uncontrolled diabetes and high blood pressure. Poisoning (by taking certain prescription medications) or a blow to the kidneys can also lead to disease. Extreme trauma, a blow directly to the kidneys could cause instant failure. Signs of failure include darkened skin, need to urinate more often, feeling itchy or numb, feeling tired and having muscle cramps.
Can I Live Without Them?
You can live a healthy and normal life with just one kidney. However, if both kidneys are damaged and about 90 percent of kidney function has been lost, you can only survive with dialysis. A dialysis machine works like an artificial kidney replicating the blood cleaning action. In extreme cases of kidney failure, long-term survival is only usually possible with donor organs.
Location: In the pelvis, behind the pelvic bone.
Function: To store urine until you are ready to urinate. Read about the urinary system.

What Can Go Wrong
Urinary Tract Infection: Also called cystitis.
Urinary Incontinence: Leakages when you sneeze.
Interstitial Cystitis: Inflammation of the bladder wall.
Bladder Cancer: Relatively common type of cancer.
The average adult bladder can comfortably hold about a pint of water, beyond this it stretches to a point where it can be painful. Once it starts to fill the bladder walls sends a nerve message to the brain that it is starting to get full and needs to be emptied. This is when you become aware of it and can make a conscious decision to go to the toilet. Urine flows out of the bladder down a tube called the urethra. The opening between the bladder and urethra is controlled by a sphincter muscle. When you decide you want to urinate, this sphincter muscles relaxes and urine flows down the urethra and out of the body. The urethra tube is much shorter in a woman than a man, which is why she is more prone to urinary tract infections. A woman's urethra is about 2.5cm long, compared to a man's which on average is 15cm. A shorter urethra means a shorter distance for the bacteria to travel to infect the bladder. The urethra starts at the bladder and ends at the vaginal opening. As the end is located very close to the anus, this is a common source of bacteria.
What Can Go Wrong
A urinary tract infection of the bladder, also known as cystitis is the most common problem. Other issues include urinary incontinence (loss of bladder control), interstitial cystitis and bladder cancer (6th most common cancer in the U.S.).
Can I Live Without It?
Yes you can live without your bladder but an alternative method of collecting your urine will be necessary. Surgical removal of the bladder (usually due to cancer) is called a cystectomy. Once it is taken out, the surgeon will either create a pouch inside your body with part of your intestines to act as a bladder, or you will need to wear an external bag to store urine outside the body.

Location: Abdomen
Function: To digest food and absorb the nutrients into the blood. Together the small and large intestines are also known as your bowels.

What Can Go Wrong
See conditions of the large intestines below which can also affect the small intestines.
Abdominal Problems: Symptom checker.

The small intestines are 5 meters long and look like a pile of coiled sausages. Although it is longer than the large intestines, it is smaller in width which is why it is called the 'small' intestines. The first section is called the duodenum. The stomach squirts small amounts of food into the duodenum where it is combined with digestives juices (bile) from the pancreas. Bile is rich in enzymes which helps to break down carbohydrates and fats; it also contains sodium bicarbonate which neutralizes the stomach acid. Food is moved along the intestines by a muscular movement called peristalsis. The lining of the intestines is covered in tiny finger-like projections called microvilli which increase the overall surface area for absorption significantly. Each microvillus contains a tiny blood vessel, through which nutrients are absorbed from the food and into the blood supply. This is how you absorb nutrients from your food. By the time food passes from the small into the large intestines, no more breaking down is necessary.
Can I Live Without It?
Yes you can. Some people do have part or all of their small intestine removed (small bowel resection), either because it is diseased (by cancer) or blocked due to a birth defect. In most cases the diseased or blocked part is removed and both healthy ends are then reconnected. If the entire small intestines needs to be removed the surgeon will make an opening in your stomach to attach a drainage bag which you need to empty regularly. This surgery is known as an ileostomy.

Location: Surrounds the small intestines.
Function: Absorb water from food passed from the small intestines and turns the remaining waste product into feces.

What Can Go Wrong
IBS: Irritable Bowel Syndrome
Inflammatory bowel disease (IBD)
Crohn's Disease
Colon Polyps
Celiac Disease
Thread Worms
Rectal or Colon Cancer
See, also, Bowel Disorders

The large intestine is about 1.5 meters long, it consists of the cecum (the first part of the large intestines to which the appendix is attached to) and the colon. Food spends up to 16 hours in this last stage of the digestive tract. The role of the large intestine is not to break food down, this was completed in the small intestines. Instead, its role is to absorb vitamins and water and to compact the remaining waste product into feces. The feces is stored in the rectum until it can be discharged via the anus. The large intestines is home to over 700 species of bacteria (bacterial flora) which play and important role in keeping our body healthy. They produce lots of vitamins, particularly vitamin K and biotin (a type of B vitamin) for absorption by the blood. This source of vitamins is particularly important at times when dietary intake is low.
What Can Go Wrong
A huge range of problems, for example diverticulitis or abscesses can form which perforate the lining of the intestines. Rectal or colon cancer can cause blockages. Minor issues like thread worms can cause an itchy bottom and constipation can cause tummy aches and excess gas.
Can I Live Without It?
Yes you can. Surgery to remove part or all of the large intestines is called a colectomy. If enough of the intestine is not damaged, the 'bad' part can be removed and then the healthy parts can be re-sewn back together. This is a relatively common surgery and most patients go on to make a full recovery. If the entire large intestines needs to be removed a colostomy is necessary. This is where the end of the intestine is pulled through the abdominal wall, and a colostomy bag is attached for removal of waste.

Location: Attached to the large intestine.
Function: Unknown

What Can Go Wrong

The appendix has no known function, scientists suspect it may have been necessary hundreds of thousands years ago by our ancestors for digesting tough foods like tree bark. Our digestion system doesn't seem to need it these days and it may very well disappear from the human body in the future. The appendix is rich in lymphoid cells which are known to fight infections. However whether or not these are used by the immune system is not known.
What Can Go Wrong
Appendicitis is where food from the intestines flows by mistake into the appendix. The appendix contracts to force the food back, but blockages can occur leading to inflammation of the appendix. This causes sudden pain around the belly button, chills, nausea, loss of appetite and vomiting. It can easily be treated by surgically removing the appendix. If the appendix bursts before treatment, you will have less pain for a short period of time, however the lining of the abdomen can then become infected and you become much sicker.
Can I live Without It?
Yes, the appendix can be removed with no known repercussions.

Other Useful Guides

Recommended Health Screenings For Women: Including Pap smear and mammograms.
Female Reproductive System: How pregnancy happens, female organs.
Reproductive Disorders In Women: Symptom checker, female cancers, PCOS, fibroids and more.
Back Problems: Check your symptoms for a cause.
Hospital Departments Explained: What each department treats.
Muscles Of The Body: Muscular system and how it works.
Bone and Joint Problems: Aches, brittle bones and other problems.
How The Female Body Develops: From puberty to menopause and old age.
Skin Care Questions: Dry, sensitive or combination. What skin type are you?
Latest Health Statistics: Life expectancy, diseases and other interesting stats.

Back To Homepage: Womens Health Advice

Please Note: Information provided on this site is no substitute for professional medical help. See Disclaimer.
Copyright. All rights reserved.