What are the organs of the body and their functions?

What are the organs of the body and their functions?

There are five vital organs in the human body which people need to keep alive. These are also a number of other organs which work together with these vital organs to make sure the body works well.

Continue reading to learn more about the body’s organs, the different organ systems and some guidelines on how to maintain optimum health.

Vital organs 

The vital organs are the ones a person will need to survive. A problem with any of these organs can get life threatening quickly.

Living without certain organs is not feasible. That said, a person can live without one of the pair in the case of the paired kidneys and lungs.

The sections below will look in more detail into the five vital organs.


The brain is the center for control of the body. By developing, receiving, and storing nerve impulses, feelings , emotions, physical sensations, and more it forms the core of the central nervous system.

The skull encloses the brain, thus protecting it against injury.

Neurologists are Physicians studying the nervous system. Researchers also described various areas of the brain over time including brain structures that operate similarly to individual organs.

The brain consists of three major subparts: the nucleus, the cerebellum and the brainstem. Inside these regions, there are many main components of the brain that form the central nervous system along with the spinal cord.

The major areas of the central nervous system include:

  • The medulla: This is the lowest part of the brainstem. It helps control heart and lung function.
  • The pons: Located above the medulla in the brainstem, this area helps control eye and facial movement.
  • The spinal cord: Extended from the base of the brain and down the center of the back, the spinal cord helps with many automatic functions, such as reflexes. It also sends messages to and from the brain.
  • The parietal lobe: Situated in the middle of the brain, the parietal lobe supports the identification of objects and spatial reasoning. It also plays a role in interpreting pain and touch signals.
  • The frontal lobe: The frontal lobe, which is located in the front of the head, is the largest section of the brain. It plays a role in many conscious functions, including personality and movement. It also helps the brain interpret smells.
  • The occipital lobes: Positioned near the back of the brain, the occipital lobe primarily interprets vision signals.
  • The temporal lobes: Located on either side of the brain, the temporal lobes play a role in numerous functions, including speech, scent recognition, and short-term memory.

The two halves of the brain are known as the right and left hemispheres. These two hemispheres are connected by a corpus callosum.


The heart is the circulatory system’s most important organ which helps deliver blood to the body. Pumping this freshly oxygenated blood through the blood vessels and around the body works with the lungs to add oxygen to the blood.

The heart has an electrical system inside too. Within the heart, electrical impulses help ensure it beats at a consistent rhythm and proper rate.

As the body needs more blood, the heart rate rises, for example during intense exercise. It diminishes during rest time.

There are four chambers inside the heart. The upper two chambers are called atria, and the lower two are called ventricles.

Blood flows from the veins of the heart and body (except the lungs) into the right atrium and then it flows into the right ventricle. It flows from there into the pulmonary artery which has branches which reach the lungs. The blood then oxygenates through the lungs.

This oxygenated blood travels from the lungs to the left atrium and then through the left ventricle, through the pulmonary veins which lead back and join together. The heart pumps the blood from there into an artery that branches out to spread blood to itself and other parts of the body (except the lungs).

The heart has four valves that make sure blood is circulating in the right direction. Heart valves are:

  • the tricuspid valve
  • the pulmonary valve
  • the mitral valve
  • the aortic valve


The lungs function by oxygenating blood with the heart. They do this by filtering the air a person breathes, and then removing excess carbon dioxide for oxygen in exchange.

Several parts of the lungs help the body take in the air, filter it and oxygenate the blood afterwards. Those are:

  • The left and right bronchi: The trachea splits into these tubes, which extend into the lungs and have branches. These smaller bronchi split into even smaller tubes called bronchioles.
  • The alveoli: The alveoli are tiny air sacs at the end of the bronchioles. They work like balloons, expanding when a person inhales and contracting when they exhale.
  • The blood vessels: There are numerous blood vessels in the lungs for carrying blood to and from the heart.

A person can live without one lung with extensive medical care but they can not survive without one lung.

The diaphragm, a thick muscle band directly below the lungs, helps the lungs expand and contract when a person breathes.


The liver is the metabolic system’s most important organ. It helps convert nutrients into usable substances, detoxifies some substances and filters blood from the digestive tract through a vein before joining venous blood flow from other parts of the body. Oxygenated blood gets through an artery to the liver.

Most liver mass is found in the upper right side of the abdomen, just below the rib cage.

The liver plays many roles in digestion and filtering the blood, including:

  • producing bile
  • helping the body filter out toxic substances, including alcohol, drugs, and harmful metabolites
  • regulating blood levels of various important chemicals, including amino acids
  • making cholesterol
  • removing some bacteria from the blood
  • making some immune factors
  • clearing bilirubin from the blood
  • regulating the process of blood clotting, so that a person does not bleed too much and does not develop dangerous blood clots

The liver is working with the gallbladder to carry bile to the small intestine. The liver pours bile into the gallbladder, which then stores and releases the bile later when the body uses it for digestion aid.

A person can live without portions of his liver, but the liver is vital to life itself.


The kidneys are a couple of bean-shaped organs, each about a fist ‘s size. They are on either side of the back and are protected inside the lower part of the rib cage. They help filter blood, and remove the body’s waste.

Blood flows from the renal artery into the kidneys. Each kidney comprises around one million tiny filtration units, known as nephrons. They help filter the waste into the urine and then return the blood filtered through the renal vein to the body.

Also, the kidneys produce urine by removing waste from the blood. Urine flows through the ureters from the kidneys, then down into the urinary bladder.

A person can live on one kidney only. When a person has severe kidney failure, dialysis can filter the blood until they get a kidney transplant, or their kidney gets some function back. Some people have to undergo long term hemodialysis.

Non-vital organs

Non-vital organs are those without which a person can live. However, this does not mean that life-threatening or harmful conditions affecting certain organs are never. Many infections and cancers in non-vital organs , especially without prompt treatment, pose life-threats.

Non-vital injuries can also damage vital organs, such as when a gallstone damages liver function.

The sections below will delineate in more detail the non-vital organs of the body.


Small and pear-shaped, the gallbladder lies just below the liver, in the right upper quadrant of the abdomen. This has cholesterol, bile salts, bile, and bilirubin.

In a healthy person, the liver releases bile into the gallbladder, which is processed by the gallbladder and then released into the small intestine to travel down the common bile duct to aid digestion.

Some people, however, develop gallstones which block the gallbladder or biliary tree, causing intense pain and digestive interference. This may also often conflict with function of the liver or pancreas.


The pancreas is located in the upper left portion of the abdomen and has two essential roles: it acts as both an exocrine gland and an endocrine gland.

As an exocrine gland, the pancreas is producing enzymes that a person needs to help digest and convert their food into energy. Amylase, lipase, trypsin, and chymotrypsin comprise these enzymes.

The pancreas also produces and releases insulin in its role as an endocrine gland, which helps the body extract glucose from the blood and convert it into energy.

Insulin problems can cause dangerously high blood glucose levels and the onset of diabetes.

In addition, the pancreas produces and releases glucagon, which increases blood glucose levels.

The principal pancreatic duct connects to the common bile duct that flows from the liver and gallbladder. Problems within the biliary tree, liver, or gallbladder may therefore also affect the pancreas.


The stomach is an organ shaped in J, near the top of the abdomen.

Food soon begins its journey into the stomach after a person swallows. The food transfers from the throat down into the esophagus. At the end of the esophagus is the stomach.

Stomach muscles help break it down, and digest food. Some regions of the stomach also contain enzymes within its lumen lining, which help digest food. For example, the enzyme pepsin breaks down proteins so they can develop into amino acids.

Also, stomach helps to store chyme until it moves into the intestines. Chyme refers to food which has combined with secretions in the stomach.

Anatomists usually divide the stomach into five subparts. These are:

  • The cardia: Located just beneath the esophagus, this portion of the stomach includes the cardiac sphincter. The sphincter prevents food from flowing back up the esophagus or into the mouth.
  • The fundus: This is situated to the left of the cardia and underneath the diaphragm.
  • The body: Food begins breaking down in the body, which is also the largest part of the stomach.
  • The antrum: This is the lower part of the stomach. It contains partially digested food before it flows to the small intestine.
  • The pylorus: This portion of the stomach connects to the small intestine. It includes a muscle called the pyloric sphincter, which controls when and how much stomach content flows into the small intestine.


The intestines are a group of tubes which help filter out waste, absorb water and some electrolytes and digest food.

Partially digested food passes first through the small intestine, consisting of three parts: duodenum, jejunum , and ileum. This is where most nutrient digestion and absorption occurs.

Food then is feces as it passes across the large intestine and inside. This begins with the cecum, spreads to the remaining colon and ends with the rectum. The rectum is the last fece stop before expulsion from the anus occurs.

Organ systems

Doctors usually list dozens of organs, although an organ is defined differently from expert to expert. Most organs play a role in the systems of organs which work together to perform certain functions.

The sections below will outline in greater detail the organ systems of the body.

Nervous system

The brain and spinal cord constitute the central nervous system, which processes and sends nerve signals, interprets information and produces thought pattern.

The peripheral nervous system is called the portion of the nervous system which communicates with the central nervous system. Overall, the peripheral and central nervous systems also include an extensive network of neurons. Those fibrous bundles located throughout the body send sensation, temperature, and pain information.

The nervous system helps the body regulate all functions including all other organs.

The stomach, for example, releases the hormone ghrelin which indicates to the brain that it is time to eat. This triggers feelings of hunger and encourages a person to eat which leads to the start of the digestion process.

The nervous system integrates with virtually any other body part. For example, when there’s an injury in that area, nerve fibers in the hand tell the brain.

Meanwhile, nerves in the skin relay information about external temperature. This can cause the brain to initiate involuntary responses, such as sweating or shivering, that control body temperature.

Other nerves also interact with the muscle, which assists in coordinating movement.

Learn more about the central nervous system here.

Reproductive system

The reproductive system includes the organs that allow a person to reproduce sexual pleasure and experience it. The reproductive system, in females, also supports a fetus’ growth.

The reproductive system works collaboratively with other organs and organs. The hypothalamus and pituitary gland, for example, help to regulate the production and release of hormones such as oestrogen and testosterone.

The male reproductive system organs include:

  • the testes
  • the epididymis
  • the vas deferens
  • the ejaculatory ducts
  • the prostate gland
  • the seminal vesicles
  • the penis
  • the bulbourethral glands

The female reproductive system organs include:

  • the mammary glands in the breasts
  • the ovaries
  • the fallopian tubes
  • the uterus
  • the vagina
  • the vulva
  • the clitoris
  • a system of various glands, such as the Bartholin glands, which help lubricate the vagina
  • the cervix


The skin is the most extensive organ in the body. It is part of the integumentary system , which includes skin , hair , nails, and fat.

The integumentary system helps to control body temperature, protect the body from harmful infections, render sunlight vitamin D and provide sensory input.

The skin consists of three structures:

  • The epidermis: This is the outer layer of skin. It contains three types of cells. Squamous cells are the outer layer of skin, which the body constantly sheds. Basal cells are the next layer, located under the squamous cells. Melanocytes produce melanin, which is skin pigment. The more melanin the melanocytes produce, the darker a person’s skin is.
  • The dermis: This is the middle layer of skin, located under the epidermis. It contains blood vessels, lymph vessels, hair follicles, sweat glands, nerves, sebaceous glands, and fibroblasts. A flexible protein called collagen holds the dermis together.
  • The subcutaneous fat layer: This is the deepest layer of the skin. It helps keep the body warm and reduces the risk of injury by absorbing heavy blows.

Muscular system

The muscular system comprises a vast muscle network. There are three muscle types:

  • Skeletal muscles: These are voluntary muscles, which means that a person can decide when to move them. The biceps and triceps are examples of skeletal muscles.
  • Cardiac muscles: These are involuntary muscles that help the heart pump blood.
  • Smooth muscles: These are also involuntary muscles. Smooth muscles line the bladder, intestines, and stomach.

Endocrine system

The endocrine system is a whole-body network of glands. Such glands release major chemicals called hormones, which help regulate virtually every organ and organ system in the body.

Progesterone, for example , helps regulate the menstrual cycle and plays an important part in sustaining a pregnancy.

There are several major glands within the endocrine system including:

  • the pancreas
  • the thyroid
  • the adrenal glands
  • the pituitary
  • the parathyroid
  • the thyroid
  • the hypothalamus
  • the pineal gland
  • the ovaries
  • the testes

Immune system

The immune system helps the body prevent infections and when they occur, it fights them off.

Many organs have a part to play in the immune system. For example, the skin prevents dangerous pathogens from entering the body, and salivary glands release saliva that may help break down some dangerous sources of food-borne infection.

The lymphatic system plays an essential role in the immune system by releasing disease-fighting lymphocytes. There are many lymph nodes throughout the body. Some people notice that their lymph nodes enlarge when they get sick.

Digestive system

The digestive system is the group of organs that digest food, as well as the different structures within which substances are released to aid digestion and absorption.

It includes:

  • the mouth
  • the esophagus
  • the salivary glands
  • the gallbladder
  • the liver
  • the pancreas
  • the stomach
  • the small and large intestines
  • the appendix
  • the rectum
  • the anus

Circulatory system

The circulatory system is composed of the many blood vessels that circulate in the body. It includes veins, arteries, capillaries, arterioles, and venules.

The lymphatic system is a part of the circulatory system as well. It helps maintain fluid balance in the body by collecting excess fluid from the blood and other particles. Within this system are lymph nodes.


Each organ within the body is its own complex system , consisting of many smaller parts. Many organs rely on several other parts of the body, too. For example, the lungs have to work with the nose , mouth, throat, windpipe and sinuses to properly breathe.

This complexity of a system of organs and organs means that certain doctors prefer to specialize in a single organ system. Cardiologists, for example, treat heart problems but while pulmonologists study the lungs.

Anyone who feels they have a problem with one of their organs or organs should see a doctor or receive referral from a healthcare provider.