Organs are the body parts formed by a group of tissues.
In a human body, there are 74 organs present in different locations.
These are the key structures in the anatomy and control many physiological functions.
They are also interlinked with each other to carry out their tasks effectively.
Any damage or disturbance to these organs significantly alters the health and well-being of an individual.
List of Organs of the body:
- Organs of Digestion: Stomach, liver, small intestine, large intestine, rectum, and anus.
- Organs of Respiration: Lungs, nose, bronchi.
- Organs of Excretion: Kidneys, urinary bladder, urethra
- Organs of Circulation: Heart, blood vessels, spleen.
- Organs of Nervous system: Brain and spinal cord.
- Organs of Reproduction: Uterus, Testis & penis in male, ovaries & mammary glands in the female.
- Organs of Endocrine system: Pituitary gland, adrenal, thyroid, pancreas, parathyroid, prostate glands.
- Organs of Senses: Skin, tongue, nose, eyes, ears.
- Organs of Immune system: Spleen, thymus, bone marrow
- Organs of metabolism: Liver
Organs in the body and their function:
It has folding called rugae by which it expands to accommodate more food. Food consumed stays in the stomach for about an hour. 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 as long tube like structure as long as 6 to 20 meters in length. It is a continuation to stomach.The food from stomach enters the small intestine and stays for 8 hours. Here the food is digested and also the nutrients absorbed into the blood.
Large intestine: This is an extension of the small intestine but is wider. It is divided as 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 which synthesize Vitamin-K and also helps in absorption of vitamin-B12.
The esophagus is the starting organs of this digestive system.
Liver: It is considered as the biggest organ in the body. It is located on the right-hand side above the stomach. It is an essential organ of metabolism and one of the principal organs human body has to detoxify substances. It helps to convert any toxic substances or drugs into water soluble inert materials. These are then easily 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 circulation system.
It is one of the organs on the left side of the body.
It helps pump the blood to reach deeper most tissues of the body.
It is the organ which functions non-stop from birth to 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.
Arteries, Veins & Capillaries:
These are duct like organs which are connected to the heart. Arteries carry blood from heart to all the tissues and cell 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 back 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 major organs of respiration. 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. These lungs are balloon-like and have the capacity to 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 till hip bones as the sacrum. It has many nerves passing through the entire body. Both brain and spinal cord are part of the nervous system.
Kidneys are the organs of excretion in the body. They filter waste from the blood flowing through blood. The nephron is the basic unit of excretion in the kidney. Each kidney has millions of nephrons which combine to perform such large demands of filtration.
Ureters: These are the long ducts which 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 area.
It accounts to 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, body expels sweat through the skin to reduce the temperature. Along with sweat sodium, chloride and other waste are excreted from the body. Thus skin also acts as an organ of excretion. Glands in skin secrete oily substance to prevent water loss and keep the skin smooth
Eyes: The most vital organs of the body.
They are responsible for vision. They have connections with the brain through optic nerves which help in vision.
Ears: These are the organs of hearing. They are a pair each located on one side of the head. They are 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 smell.
Tongue: The organ of taste in the mouth. It has sensory buds to recognize the taste. It is movable and helps in speech and talking.
Pancreas: This organ located near stomach acts as both an exocrine gland and also endocrine gland. 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 endocrine gland located along with 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 secrete 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 intestines and stomach. It is involved infiltration of blood, destruction of old and worn out red blood cells. This also serves as a reservoir of blood and also recovers iron from damaged RBC for reuse.
Gallbladder: It is a small organ below the liver. Here the bile juice from liver is concentrated before being released into gut. See the image above for location.
Thymus gland: An important organ of immune system, located near the sternum. This organ helps in development of immune cells. It decreases in size as age progresses.
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 females. It helps to host the fertilized zygote to grow 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 a 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 function to expel the urine out of the body.
Reference: Principles of Anatomy and Physiology.
Organs of all the mammals work in similar pattern. They are controlled by the same set of hormones in the body and stimulated by same receptors. Hence Knowledge of organs of the body, helps one understand the disease mechanisms and also gives ideas for pharmacology based intervention. Even organs from animals are isolated for drug testing through ex vivo techniques.