An organ is a structure that has a specific shape and function in the body. And there are approximately 74 major organs in the human body that combine to form organ systems. The essential organs in different human anatomy locations are as below.
List of Organs of the body
- Organs of Digestion: Esophagus, Stomach, liver, pancreas, small intestine, large intestine, rectum, anus, and mesentery.
- Respiration: Lungs, nose, trachea, bronchi.
- Excretion: Kidneys, urinary bladder, urethra, ureters.
- Circulation: Heart, blood vessels, spleen.
- The Nervous system: Brain and spinal cord.
- Reproduction: Testis & penis in the male. Uterus, ovaries & mammary glands in the female.
- Endocrine system: Pituitary gland, adrenal, thyroid, pancreas, parathyroid, prostate glands.
- Sense organs: Skin, tongue, nose, eyes, ears.
- Of the Immune system: Spleen, thymus, bone marrow, lymph nodes, lymph vessels.
Organs in the body and their function in detail
Each organ is made up of a group of tissues. And based on this, each organ has a specific set of tissues and also a particular shape to suffice the needs of the body.
These organs start from the mouth and end with the rectum. They are of different types like
- Small intestine
- Large intestine
Mouth and Pharynx
The mouth is the entry point for any food substance to enter the human body.
The mouth has teeth, a tongue, and salivary glands.
Here, the food is chewed, moistened, and sent to the stomach through the esophagus.
This is the organ that has a tube-like structure and connects the mouth and stomach.
In the digestive system, it helps the passage of food from the mouth to the stomach.
It is one of the largest internal organs having a sack-like structure.
It is located in the belly portion of the body, tilted towards the left of the axis.
In an adult, it has a capacity is up to 2.5 liters.
It has foldings called rugae which expand to accommodate more food.
Food consumed stays in the stomach for about an hour or two.
The stomach wall secretes HCl and gastric juice. HCL destroys any microbes in the food while the amylase in the gastric juice digests carbohydrates.
The stomach wall readily absorbs water, alcohol, and digested carbohydrates.
This is a long tube-like structure with a length of about 5 to 6 meters.
It is a continuation of the stomach up to the Cecum and has three major parts like
The food from the stomach enters the small intestine at the duodenum.
The duodenum is of 25cms long, and it receives the secretions of bile juice and pancreatic juice.
The jejunum is 3 meters long, and the ileum is 3 meters long.
Here, in the small intestine, there is a mixing of food with digestive juices, and chemical digestion and also absorption of food take place.
The food stays here for approximately 8 hours before entering the large intestine.
This is an extension of the small intestine but has a greater diameter. It is 1.5 meters long and can be divided into
- ascending colon,
- transverse colon,
- descending colon,
- sigmoid colon and
This organ of the digestive system helps in the absorption of water from undigested food; stores the bowel before being excreted as feces.
Further, it hosts many gut-friendly bacteria that synthesize Vitamin-K and also help in the absorption of vitamin B12.
This is a recently discovered structure and is thought to be a complete organ as it functions specifically and has a complete structure.
The mesentery helps to fix the intestine to the abdominal walls like glue.
Accessory organs of digestion
These are the vital organs that aid in digestion. These consists of
- Salivary glands
There are three pairs of salivary glands in the facial region. They secrete saliva into the mouth to keep it moist and help in the digestion of carbohydrates.
It is considered the biggest organ in the human body. It weighs around 2 to 3 kg making it the heaviest internal organ in a healthy adult.
It is located on the right side of the body above the stomach, as seen in the image above.
It is an essential organ of metabolism and one of the principal organs in the human body that detoxifies substances.
It helps to convert any toxic substances or drugs into water-soluble inert materials. These are then readily excreted by the kidneys.
It is the organ where glucose is stored as glycogen and fat are converted to high-density and low-density lipoproteins.
It is also the place where bile is formed and released into the intestine for excretion. It is the most robust and active organ in the body. Damage to any portion of the liver is regenerated and repaired for efficient function.
It is a small organ below the liver. Here the bile juice from the liver is concentrated before being released into the gut. See the image above for the location.
This organ located near the stomach acts as both an exocrine gland and also the endocrine gland.
While the endocrine part secretes hormones like insulin, and somatotropin, which regulates glucose levels in the blood.
Organs of Circulation
These include the heart and blood vessels like the arteries, veins, and capillaries.
This is the primary organ of the blood circulatory system. It is one of the organs on the left side of the body.
The heart’s function is to pump blood to reach the body’s deeper tissues.
It is the organ that functions non-stop from the time of its formation in the womb until an individual’s death.
It has veins flowing in blood from the back and arteries going out of the heart. In an adult, it beats at an average of 72 beats per minute. It is made of cardiac muscles, which are part of the muscular system.
Arteries, Veins & Capillaries
These are duct-like organs that are connected to the heart. Arteries carry blood from the heart to all the tissues and cells of the body.
Veins bring impure blood from all the tissues and cells back to the heart. Capillaries are the finest ducts that emerge from arteries and converge again into veins.
They reach the cells, provide nutrition, and collect waste for expulsion by blood. There are few structural and functional differences between arteries and veins.
Organs of respiration
The list includes
These are the principal organs of the respiratory system.
They take oxygen-rich air from the atmosphere into the body and expel carbon dioxide.
The oxygen from the air in the lungs is carried by blood circulating through the alveoli.
These lungs are sponge-like and can constrict and dilate. The average capacity is 4 liters of air.
Organs of the nervous system
This is the master organ of the body as all the organ systems of the human body are under its control.
The skull, which is a bony frame of the head, houses the brain.
The brain is made up of nerve cells and neuroglia.
It consists of parts like the cortex, cerebral hemisphere, cerebellum, medulla oblongata, and pons. It extends into the spinal cord.
For more details, refer to the article Parts of the brain.
Its essential functions include judgment, memory, reasoning, sleep, temperature control, body movements, reflex actions, etc. It exerts its action through neurotransmitters.
This is the long cord located in the vertebral column.
It begins from the base of the brain and extends to hip bones into the sacrum.
The spinal cord gives out many nerves that pass through the entire body.
Along with the brain, it is a part of the nervous system.
Organs of the urinary system
These are the main organs involved in the excretion process.
There is a single pair of kidneys present on the dorsal side of the body in such a way that each kidney is located on either side of the vertebral column.
Kidneys are bean-shaped and brownish in color with millions of nephrons inside.
These nephrons form an efficient filtration mechanism.
The waste from the blood is removed as it passes through millions of nephrons.
This filtrate waste is sent into the urinary bladder through the Ureter.
These are the long ducts that connect the kidneys to the urinary bladder.
They carry the formed urine from nephrons to the bladder for expulsion.
This is a storage vesicle that stores urine brought from the kidneys by the ureters until there is voluntary urination.
This tube-like extension originates from the urinary bladder and opens to the outside.
These constitute five major organs which are parts of different organ systems. These include
This is the largest organ of the body in terms of area. It belongs to the integumentary system.
It accounts for a few square meters in area. It covers the whole body, gives shape, and protects the inner tissues from germs.
It also acts as an organ of the sense of touch. The skin has sweat ducts, oil glands, and hair. In times of excess heat, the body expels sweat through the skin to reduce body temperature.
Sweat, sodium, chloride, and other waste are excreted from the body. This skin also acts as an organ of excretion.
Glands in the skin secrete an oily substance to prevent water loss and keep the surface smooth.
The eyes are one of the 5 sense organs. They are the most vital organs which help in daily life activities.
They are a pair located in eye sockets in the skull on the front side of the head.
They are responsible for vision. The eyes are connected to the brain through optic nerves, which help in sight.
They work together with the ears for better balance, with the nose and tongue to enhance the appetite at the sight of food.
These are meant for hearing and body balance. They are a pair, each located on one side of the head.
The ears perform specific functions like the sense of hearing and the maintenance of body balance.
This way, they help in communication and safety.
This is an organ of respiration but also has the function of the sense of smell.
It has olfactory nerve endings in the nasal layers, which predict the scent.
It also has hair to catch dust entering the respiratory tract.
This is the organ located in the mouth. It has sensory buds which act as chemoreceptors.
The specific functions of the tongue are to recognize the taste, make a speech, and chew the food.
This gland is located in the brain but releases important organs that regulate body physiology.
This is an endocrine gland located near the neck region. It secretes thyroid hormones, which regulate metabolism and also body temperature.
This is also the endocrine gland located along with the thyroid gland. They secrete parathormone, which regulates calcium levels in the blood.
This endocrine gland has two portions the inner medulla, which secretes epinephrine, while the outer cortex secretes mineral and glucocorticoid hormones.
Epinephrine is the fight or flight hormone (emotion-related), while corticoids regulate body metabolism.
This is a small reddish-brown colored gland present in the brain. It secretes the hormone melatonin, which regulates the circadian rhythm.
Refer for more details on glands in the body
Organs of the Lymphatic system
This includes organs like
This organ is a part of the lymphatic system. It is located in the belly region near the intestines and stomach. It is involved in the infiltration of blood and the destruction of old and worn-out red blood cells. This also serves as a reservoir of blood and even recovers iron from damaged RBC for reuse.
An essential organ of the immune system, located near the sternum. This organ helps in the development of immune cells. It decreases in size as age progresses.
These are oval-shaped organs lying along the length of the lymph vessels. They help in the filtration of lymph, destruction of cell debris, and proliferation of T and B-lymphocytes.
These are the vessels that are found running beside the blood vessels. They carry the lymph away from tissues to mix into venous blood.
Reproductive system organs
The organs can be differentiated into male and female organs.
The male organs include
These are the external gland-like structures present in males near the groin. They have vas-differentia, which forms sperms.
This gland secretes the prostate hormone. Present in males helps in the passage of sperms from the urethra.
This is present only in males. It is a sexual organ and also functions to expel urine out of the body.
The female organs include
This organ is well developed in the female reproductive system. It helps to host the fertilized zygote for nine months.
Here the zygote grows into a baby. It provides all the required nutrients to the baby during the period.
These are present in women as extended portions of the uterus, as seen in the picture above.
They are a pair and help form ova, which can fertilize with sperm and form a baby.
This is tissue, not an organ, and is present inside the large bones. It exists as yellow and red bone marrow.
As a person ages, the red portion of it turns yellow. This bone marrow is essential in producing red blood cells, white blood cells, and even thrombocytes.
- This is a series of interconnected compartments of cells and the secretions in the body which are present around all the essential organs.
- They act as a shock absorber and help protect the organs from jerks and movements by the body.
- The Interstitium is also responsible for the chemotaxis phenomenon whereby the white blood cells move to the specific region of injury.
Frequently Asked Questions and Answers
What are the 5 vital organs?
A vital organ is one without which the body cannot survive for long. We can list 5 of them as 1. Brain, 2. Heart, 3. Lungs, 4. Liver, and 5. kidneys.