5 Major Organs of the Body

An organ is a group of tissues arranged to form a structural unit specialized to perform a common function. Tissues are a group of structurally similar cells that perform the same function, and tissues of different types combine to form an organ. Brain, heart, kidney, and lungs are a few examples of organs.

5 Vital Organs of a Human Body
The human body consists of 5 major organs considered vital for survival; the brain, heart, lungs, liver and kidney. We can not live without any of these 5 vital organs, and any problem with any of these organs requires immediate medical attention; otherwise, it could be life-threatening. Now let’s have a look at these organs in detail.

The brain is the most complex organ of the human body located in the head and is protected within the skull. It functions as the body's control center that controls thought, emotion, memory, motor skills, vision, physical sensations, blood pressure, breathing and more. The brain and spinal cord, together they form the central nervous system. The brain is divided into three main parts; the cerebrum, the cerebellum, and the brainstem.

It is the largest part of the brain and is divided into two hemispheres. The hemisphere is divided into four lobes: the frontal lobes, parietal lobes, temporal lobes, and occipital lobes.

The cerebellum is located at the back of the head below the occipital lobes and helps maintain posture, balance, and equilibrium.

The brainstem connects the cerebrum to the spinal cord and cerebellum and comprises the midbrain, pons, and medulla oblongata.

The heart is a fist-sized muscular organ located between the lungs in the middle of the chest, slightly left of the chest bone. The heart pumps blood and circulates oxygen and nutrients throughout the body through the circulatory system.
The heart is divided into four chambers: two upper chambers (the right and left atria) and two lower chambers (the right and left ventricles)

Right atrium
The right atrium receives the deoxygenated blood via the vena cava, the two largest veins. The superior vena cava carries blood from the brain and arms, and the inferior vena cava carries blood from the legs and abdomen into the right atrium. Then the right atrium transmits the blood to the right ventricle.

Right ventricle
The right ventricle pumps the received deoxygenated blood to the lungs via the pulmonary artery.

Left atrium 
The pulmonary vein carries the oxygenated blood from the lungs to the left atrium, which pumps the blood to the left ventricle.

Left ventricle
The left ventricle is responsible for pumping oxygenated blood to all body parts.

The lungs are the leading organs of the respiratory system. We have two lungs located in the chest cavity on either side of the chest. The right lung is divided into three lobes, an upper, middle and lower lobe, and the left lung has two lobes, an upper and a lower lobe. The lungs are protected and cushioned by two thin layers of tissues called the pleura. The lungs and primary function is to extract the oxygen from the air we breathe, pass it into the bloodstream, and remove carbon dioxide and release it into the atmosphere. The trachea or windpipe divides into left and right bronchi, connected to the lungs. In the lungs, the bronchi further split into smaller tubes called bronchioles.  The alveoli are tiny sacs at the end of the bronchioles, where the oxygen is transferred from inhaled air into the blood. The oxygenated blood is then transferred from the lungs to the heart via pulmonary veins.

The liver is the largest organ of the body after skin, weighing around 3 pounds. Reddish-brown in color, the liver sits in the right upper portion of the stomach just below the diaphragm. The liver is half-moon shaped and has two sections or lobes. The liver performs many important functions, including filtering blood coming from the digestive tract, filtering out toxic compounds, bile secretion, regulating blood sugar level and more.
Let’s now discuss the function of the liver in detail:

  • The liver produces bile, an important fluid for the digestion process as it breaks fats in the small intestine.
  • It produces albumin, the most abundant plasma protein that helps maintain the vascular system’s oncotic pressure and carries hormones, enzymes, and medicines throughout your body.
  • Blood coming from the stomach and intestine gets filtered into the liver. It breaks down and removes toxins, byproducts, and other harmful substances.
  • The liver produces proteins that play a key role in regulating the process of blood clotting.
  • It converts excess glucose from the bloodstream into glycogen for storage, which can later be
    converted into glucose as needed.
  • It fights infections by removing some bacteria from the bloodstream and making immune factors.


The kidneys are bean-shaped organs about the size of a fist. They are located just below the ribs on either side of the spine. The kidneys are the urinary system's primary organs and consist of about a million tiny units called nephrons. Each nephron consists of a filter called the glomerulus and a tubule.
Kidneys perform many vital functions:

  • Purify blood by removing the waste products.
  • Maintain fluid balance by excreting excess amount of water as urine.
  • Regulate minerals and chemicals like sodium, potassium, calcium, phosphorus, magnesium and more in the blood.
  • Maintain blood pressure level.
  • The kidney produces erythropoietin, a hormone that stimulates the production of red blood cells.
  • Promote bone health by converting vitamin D into its active form.
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