The human body is made up of several different organ systems, with each organ playing a very specific and important role in maintaining homeostasis and keeping the body alive and healthy. In this article, you’ll learn the detailed functions of the organs of the body, in particular the brain, heart, lungs, liver, kidneys, stomach, intestines, pancreas and reproductive organs.
Functions of the brain and nervous system
The brain is the central organ of the nervous system and responsible for coordinating the processes of all the other parts of the body to keep things working optimally. The brain is highly complex and we don’t fully understand all of its functions and capabilities, but in general it regulates the actions of all the other organs, perceives sensory information from external and internal stimuli, and sends impulses to muscles to permit movement. It does this by sending electrical or chemical signals from neuron to neuron, which has a cascade effect and modulates the functions of other organs.
As a simplified example, let’s say you hear a sudden loud noise and are startled, and you can feel your heart racing afterwards. Sensory information (the loud noise) traveled through your ears to the auditory nerve, which sent a signal to your brain allowing you to perceive the sound. This triggered a combined emotional/physiological response within your brain which caused certain neurons to release the chemical norepinephrine, which stimulates receptors on the heart, causing it to beat faster.
Functions of the heart and lungs
The heart and lungs work together closely to deliver oxygen to all of the cells of the body, while removing waste gases from cellular respiration (such as carbon dioxide). The heart pumps blood through every part of the body, distributing nutrients, hormones and oxygen. This is why your heart rate increases when doing strenuous activity: your cells are expending more energy and thus require more oxygen, causing your breathing to become labored and your heart to pump faster to get that oxygen where it needs to go, fast.
Functions of the liver and kidneys
The liver and kidneys are the main organs responsible for removing toxins from the body. The liver filters many chemical substances (including many medications and toxins like ethyl alcohol) out of the blood and metabolizes them through various chemical reactions into simpler byproducts that can be eliminated from the body, usually through urination. The kidneys then filter these byproducts out of the blood and concentrate them into urine, which can exit the body through urination. The liver also produces cholesterol, certain blood clotting factors, and bile.
Functions of the stomach and intestines
As part of the digestive system, the stomach and intestines are responsible for digesting food and absorbing its nutrients so they can be used by the body. The stomach secretes a strong acid and physically churns food to break it down so that nutrients can be extracted more easily; it also plays a small role in absorption of certain substances. Most of the nutrients from food are absorbed as it is digested in the small intestine. The large intestine or colon absorbs any useful substances that are left behind and sends the remaining compacted waste to the rectum to be eliminated as feces.
Functions of the pancreas
The pancreas is an organ that is considered part of the endocrine system, and is responsible for aiding in digestion and regulating blood sugar. The pancreas produces digestive enzymes and releases them into the duodenum of the small intestine, where the stomach deposits partially digested food. These help the intestine digest the proteins, carbohydrates and fats in the food we eat. The pancreas also manufactures two important hormones for regulating blood sugar, namely insulin and glucagon, which have inverse functions.
Functions of the reproductive organs
The reproductive organs, which are different in men and women, of course serve the purpose of allowing for sexual reproduction and creation of offspring. These organs also have endocrine functions, meaning they produce certain important hormones for the body.
In men, the reproductive organs are the testes, which produce sperm cells (male gametes) and the sex hormone testosterone. In women, the homologous organs are the ovaries, which produce ova (or eggs, female gametes) and the sex hormones estrogen and progesterone.