The human body is a scientific marvel that functions as a self-sustaining unit. It gains energy to carry out its functions from the food we eat. It takes up oxygen from the air, and breaks down the complex energy molecules from food into free energy, through the processes of digestion and cellular respiration. These organs function individually, and carry out one or more special functions. By considering skin as the largest organ of the human body, the number of internal organs is 23. The interior parts of the eyes and ears, as well as the tongue can also be added to this list, increasing the total to 25. Provided below is a list of internal organs in alphabetical order.
They are triangular-shaped endocrine glands. They are located over the top of the kidneys. Their main function is to release the hormones in response to stress.
It is a blind-ended tube that is connected to the cecum. The appendix is located near the junction of the small and large intestines. There are no known appendix functions, and it is considered to be a vestigial organ. People who have their appendix removed have never reported any kind of problem with their health.
In this organ, the urine that is filtered from the kidneys is collected before being disposed off by urination. The bladder is a muscular organ that is elastic (distensible) in nature. It is located on the pelvic floor. In males, the base of the bladder is between the rectum and pubic symphysis, and in females, it is below the uterus and above the vagina.
It is the most important organ of the human body, and it controls all the other parts. It is the center of the nervous system, and is the most complex of all internal organs. The brain controls our sense of vision, hearing, taste, smell, balance, and feeling. There are 15 to 33 billion neurons in the brain that depend on the age and sex of an individual. This organ controls the others either by secretion of chemicals, or activation of the muscles. A highly evolved human brain is what differentiates man from other vertebrates, making us the most intelligent of all species.
It is a long muscular tube that passes from the pharynx into the stomach. The word 'esophagus' is derived from a Greek word oisophagos, which means 'entrance for eating'. This organ connects the mouth to the stomach, and is about 25 to 30 cm long.
It is also known as the cholecyst, and is one of the small internal organs of the human body. It helps in the process of digestion, and also is the site for storage of bile produced in the liver. It is located in the concave portion of liver that is called the gallbladder fossa. The length of this portion is about 8 cm in adults when fully distended.
After the brain, the heart is the second most important internal organ in humans. It is a muscular organ whose main function is to pump oxygenated blood throughout the body through blood vessels. This action is carried out by repeated and rhythmic contractions. On an average, the human heart beats about 72 times per minute, and weighs 250 to 300 gm in females, and 300 to 350 gm in males.
They are a segment of the alimentary canal, and they extend from the stomach to the anus. They are divided into: small intestine and the large intestine. The former one is further subdivided into duodenum, jejunum, and ileum. The latter one is consists of the cecum and colon.
They serve as the most important part of the urinary system. Their function is regulation of electrolytes, maintenance of acid-base balance, regulation of blood pressure, production of urine, etc. They help in excreting urea and ammonium from the body, and reabsorb water, glucose, and amino acids. Calcitriol, renin, and erythropoietin hormones are produced by this organ.
It is one of the most vital internal organs of the human body. The liver is an absolute necessity for survival. It carries out several functions including detoxification of blood, production of biochemicals for digestion, and protein synthesis.
These organs that are responsible for respiration. In humans, a pair of lungs is located in the chest on either side of the heart. Their function is to transport atmospheric oxygen into bloodstream, and release carbon dioxide from blood into the atmosphere.
They are ovum-producing reproductive organs that are present in pairs in females. They are located in the lateral wall of the pelvis. This region is called the ovarian fossa, which is present below the external iliac artery and in front of the internal iliac artery and ureter.
They belong to both the endocrine and digestive systems. These organs produce important hormones like insulin, glucagon, and somatostatin. They also produce pancreatic juice that contains digestive enzymes. If the pancreas do not function normally, it may lead to diabetes mellitus.
These glands are located below the thyroid gland in the neck. They produce the parathyroid hormones, and control the amount of calcium in the blood and within the bones.
It is a part of the endocrine system. It is just about the size of a pea, and is located at the base of the brain in the small bony cavity covered by a dural fold. This organ is called the master gland that secretes hormones for various homeostatic processes. It also releases hormones that stimulate other glands for secretion of other chemicals.
It is a part of the male reproductive system, and its function is to secrete a milky fluid that contains semen, spermatozoa, and seminal vesicle fluid. It also controls the flow of urine during ejaculation.
The organ is very important with respect to the immune system. It is located in the left upper quadrant of the abdomen. Its function is to remove old red blood cells and also to recycle iron. The spleen in an adult human body is about 11 cm in length.
The muscular, hollow bag in the alimentary canal is called the stomach. It is the primary organ of the digestive system that is involved in the second phase of food digestion. The location of this organ is between the esophagus and small intestine. Its function is to churn food with the help of smooth muscular contortions, and to secrete protein-digesting enzymes and strong aids for food digestion. It then passes the partially digested food towards the small intestine.
They are present in males, and are the generative glands of this sex. They produce sperms and male sex hormones like testosterone. There are two testes in a healthy male.
It is a specialized organs of the immune system, and is located in front of the heart and behind the sternum. The function of this organ is the production of T-lymphocytes that are very important for adaptive immune system.
The largest endocrine gland of the human body is the thyroid gland, which is located in the neck. The hypothalamus and pituitary glands control this gland. It helps to control the use of energy in the body, makes proteins, and also controls the sensitivity of the body towards other hormones.
It is the most important part of the female reproductive system. This organ is internally connected to the fallopian tubes on each side, and opens into the vagina at one end. In this organ, the fetus develops during gestational period. Other functions are to provide support and structural integrity to the bladder, bowel, and pelvic organs. It is a very important part of sexual response in females as it directs the blood flow to the pelvis, ovaries, vagina, labia, and clitoris. The uterus accepts the ovum from the fallopian tube, and implants it into the endometrial wall. Here, it nourishes the ovum till it is fertilized. An unfertilized ovum along with the blood and endometrial lining is pushed out of the uterus. This leads to the beginning of menstrual cycle every month in women after attaining puberty.