Basics of Homeostasis
In general, homeostasis refers to the balance within a system that keeps it operating within a range of conditions. Homeostasis helps animals maintain stable internal and external environments with the best conditions for it to operate. It is a dynamic process that requires constant monitoring of all systems in the body to detect changes, and mechanisms that react to those changes and restore stability.
There are three components to homeostatic regulation in animals: the receptor, the control center, and the effector. Receptors are constantly surveilling conditions and detect changes that take conditions outside the normal range, away from a set point. The control centers receive and process the information from the receptors and give commands to the effectors on how to respond.
The Importance of Homeostasis
The failure of homeostatic regulation in just one body system will cause conditions to deteriorate and it may be fatal. For the health of an organism, all homeostatic regulation mechanisms must function properly. The information below describes how various body systems contribute to overall homeostasis.
Nervous System
The nervous system maintains homeostasis by controlling other parts of the body. It comprises the central nervous system and the peripheral nervous system. The peripheral nerves are those outside of the brain and spinal cord which go to the limbs and organs. The brain and spinal cord make up the central nervous system. The hypothalamus in the brain is particularly important for maintaining homeostasis because it controls the actions of the medulla oblongata (involuntary functions), the autonomic nervous system (smooth muscle and glands), and the pituitary gland (hormone excretion).
Endocrine System
This system comprises the glands that excrete hormones into the bloodstream. Hormones have a myriad of functions in the body that maintain homeostasis by targeting certain tissues. Besides regulating bone growth, muscle metabolism, and energy production, there are hormones that regulate fluid balance, the production of red blood cells, blood pressure, and inflammation.
Integumentary System
The skin helps to regulate body temperature through dilation and constriction of blood vessels, the production of sweat, and shivering. It also regulates the balance of water and other solutes through its surface. Hairs in the nose and other body orifices protect the body from particles, debris, and bacteria. The skin also synthesizes Vitamin D from cholesterol needed for bone growth, maintenance, and repair.
Skeletal System
The bones of the skeleton protect the brain, spinal cord, and internal organs and serve as a reservoir of calcium, phosphorous, and other minerals. Calcium, for example, is needed for muscle contraction. Red and white blood cells and other cells of the immune system are made and stored in the bone marrow. The skeleton also makes movement of the body possible which is important for homeostasis. An example of this is when an animal’s core temperature becomes too hot, it can move into the shade of a tree or into the water to cool itself.
Muscular System
Muscles not only work with the skeleton to move the body, but they make digestion and breathing possible. The layers of muscle also protect internal organs and generate heat when they contract (useful for shivering when the body is cold). Finally, the heart is made of cardiac muscle and its pumping of blood is necessary for many of the homeostatic control systems in the body.
Lymphatic System
This system is key to maintaining homeostasis by controlling blood volume and tissue fluids. The lymphatic system works with the capillaries in the cardiovascular system to remove excess fluid which can build up and cause edema and swelling. The lymphatics are also a critical part of the immune system and immune response. After B cells mature in the bone marrow, they migrate to the lymph nodes where they stand guard against foreign invaders in the body. Other parts of the lymphatic system that help maintain homeostasis are the lymph glands, tonsils, adenoids, spleen, and thymus gland.
Respiratory System
The respiratory system transports gases like oxygen and carbon dioxide in and out of the lungs. This is critical to maintaining the proper pH of the blood. If the blood is too acidic, the brain slows the breathing to increase the amount of bicarbonate ions (carbon dioxide) in the blood. Conversely, to adjust the blood chemistry when the pH is too low, respiration increases so that more carbon dioxide is expelled. The respiratory system also acts to dissipate heat when the body temperature gets too hot. This is done through open-mouth breathing or panting in animals that don’t have sweat glands.
Digestive System
The digestive system helps maintain homeostasis by eliminating toxins and waste and supplying nutrients to the body. It also serves the critical immune system function of destroying bacteria and viruses than enter the body through food and water intake. Also, the heat generated during the digestive process contributes to regulation of the core temperature.
Urinary System
The body eliminates nitrogenous waste through urine which is important for maintaining homeostasis in the body. The urinary system also helps control blood pressure by regulating the amount of fluid and ions in the body. Also, the kidneys produce the hormone erythropoietin which stimulates red blood cell production in the bone marrow.
References
- OpenStax College. (2018). Concepts of Biology. Houston, TX. OpenStax CNX. Retrieved from http://cnx.org/contents/b3c1e1d2-839c-42b0-a314-e119a8aafbdd@9.39
- Homeostasis. (n.d.). In WikiBooks, Human Physiology. Retrieved April 4, 2018 from https://en.wikibooks.org/wiki/Human_Physiology/Homeostasis