There are approximately 74 major organs in the human body. They combine together to form the organ systems which carry out our body vital functions.
Below, we will see important organs that are present in different locations of human anatomy.
List of Organs of the body:
As you know, organs are formed by a group of tissues. They can be grouped in different sections like
- Organs of Digestion: Esophagus, Stomach, liver, pancreas, small intestine, large intestine, rectum, and anus.
- Organs of Respiration: Lungs, nose, trachea, bronchi.
- Organs of Excretion: Kidneys, urinary bladder, urethra
- Organs of Circulation: Heart, blood vessels, spleen.
- Organs of the Nervous system: Brain and spinal cord.
- Organs of Reproduction: Testis & penis in the male. Uterus, ovaries & mammary glands in the female.
- Organs of the Endocrine system: Pituitary gland, adrenal, thyroid, pancreas, parathyroid, prostate glands.
- Organs of Senses: Skin, tongue, nose, eyes, ears.
- Organs of the Immune system: Spleen, thymus, bone marrow
- Organs of metabolism: Liver
Organs in the body and their function:
Stomach: It is one of the largest internal organs of the body. It is a sack-like structure located in the belly portion of the body. Its capacity is up to 2.5 liters.
It has folding called rugae by which it expands to accommodate more food. Food consumed stays in the stomach for about an hour. The stomach wall secretes HCl which destroys any microbes in the food. Further, it readily absorbs water and alcohol and digests some portion of carbohydrates.
Small intestine: This is a long tube-like structure as long as 6 to 20 meters in length. It is a continuation to the stomach. The food from the stomach enters the small intestine and stays for 8 hours. Here the food is digested and then the nutrients are absorbed into the bloodstream.
Large intestine: This is an extension of the small intestine but has a greater diameter. It is divided into ascending colon, transverse colon, descending colon, sigmoid colon and rectum. It helps in absorption water from undigested food; it stores bowel before being excreted as feces. Further, it hosts many friendly bacteria that synthesize Vitamin-K and also helps in the absorption of vitamin-B12.
The esophagus is the starting organs of this digestive system.
Liver: It is considered the biggest organ in the human anatomy. It is located on the right-hand side above the stomach. It is an essential organ of metabolism and one of the principal organs of 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.
Heart: This is the primary organ of the blood circulatory system. It is one of the organs on the left side of the body.
It is the organ that functions non-stop from the time of its formation in the womb till the death of an individual.
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 finest ducts which emerge from arteries and converge again into veins. They reach deeper most cells and provide nutrition and collect waste for expulsion by blood. There are few structural and functional differences between arteries and veins.
Lungs: These are the principal organs of the respiratory system. They help in taking of oxygen-rich air from the atmosphere into the body and give out carbon dioxide.
The oxygen from the air in the lungs is carried by blood when it circulates through the alveoli. These lungs are balloon-like and can expand and relax. The average capacity is 4 liters of air.
It is made up of nerve cells and neuroglia. It consists of parts like cortex, cerebral hemisphere, cerebellum, medulla oblongata, pons. It extends into the spinal cord. Its essential functions include judgment, memory, reasoning, sleep, temperature control, body movements, reflex actions, etc. It exerts its action through neurotransmitters.
Spinal cord: This is the cord located in the vertebral column. It begins from the brain and extends to hip bones like the sacrum. It has many nerves passing through the entire body. Both the brain and spinal cord are part of the nervous system.
Kidneys: These are the main organs of the excretory system. They are involved in removing waste from the blood. There is a single pair of kidneys present towards the dorsal side of the body. They are bean-shaped and brownish in color. Each kidney is located on either side of the vertebral column.
Kidneys are the organs of excretion in the body. They filter waste products from the blood for expulsion. A nephron is the basic unit of excretion in the kidney. Each kidney has millions of nephrons that combine to perform such large demands of filtration.
Ureters: These are the long ducts that connect kidneys to the urinary bladder. They carry the formed urine from nephrons to the bladder for expulsion.
Urinary bladder: This is a storage vesicle which stores urine brought from kidneys by the ureters until there is voluntary urination.
Skin: This is the largest organ of the body concerning the area.
It accounts for a few meters. 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 the temperature. Along with 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
Eyes: The most vital organs of the body.
They are a pair located in eye sockets in the skull on the front side of the head.
They are responsible for vision. Eyes are connected to the brain through optic nerves which help insight.
Ears: These are the organs of hearing. They are a pair each located on one side of the head. An ear is responsible for the sense of hearing and maintenance of balance.
Nose: 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.
Tongue: The organ of taste in the mouth. It has sensory buds to recognize the taste. It is movable and helps in speech and talk.
Pancreas: This organ located near the stomach acts as both an exocrine gland and also the endocrine gland. The exocrine gland secretes digestive enzymes like amylase, trypsin, lipase which digest carbohydrates, proteins and fats respectively. See the pancreatic enzymes for more details
While the endocrine part secretes hormones like insulin, somatotropin which regulate glucose levels in the blood.
Thyroid gland: This is an endocrine gland located near the neck region. It secretes thyroid hormones which regulate metabolism and also body temperature.
Parathyroid gland: This is also the endocrine gland located along with the thyroid gland. They secrete parathormone which regulates calcium levels in the blood.
Adrenal gland: This endocrine gland has two portions as inner medulla which secretes epinephrine while the outer cortex secretes mineral and glucocorticoid hormones. Epinephrine is the hormone of fight or flight (emotion-related) while corticoids regulate body metabolism.
Salivary glands: There are three pairs of salivary glands in the facial region. They secrete saliva into the mouth to keep it moist.
Spleen: 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, 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.
Gallbladder: 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.
Thymus gland: 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.
Ovaries: These are present in women near the lower part of the belly.
They are a pair and help in the formation of ova which can fertilize with sperm and go on to form a baby.
Refer for more details on glands in the body
Uterus: This organ is well developed in the female reproductive system. It helps to host the fertilized zygote for 9 months. Here the zygote grows into a baby. It provides all the required nutrients to the baby during the period.
Testis: These are the external gland-like structures present in males near the groin. They have vas-differentia which forms sperms.
Prostate gland: This gland secretes prostate hormone. Present in males helps in the passage of sperms from the urethra.
Bone marrow: This is tissue and 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 the production of red blood cells, white blood cells, and even thrombocytes.
Penis: This is present only in males. It is a sexual organ and also functions to expel the urine out of the body.
Interstitium: This is a series of interconnected compartment of cells and the secretions in the body which are present around all the essential organs. They act as a shock absorber and help in protecting 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.
Reference: Principles of Anatomy and Physiology.
Organs of all the mammals work in a similar pattern. They are controlled by the same set of hormones and receptors. This knowledge of human organs helps us understand disease mechanisms and provide ideas for medical intervention. This is the reason why organs from animals are isolated for new drug testing in the labs.