Homeostasis in Biology – Definition | Mechanisms of Homeostasis

Homeostasis

• The body’s ability to maintain a relatively stable internal environment in spite of external changes is called homeostasis. This term was first coined in the 1930s by the American physiologist Walter Cannon. Homeostasis refers to the body’s ability to maintain a constant internal environment, or set point. This set point is determined by a number of factors, including the body’s metabolism, blood pressure, and blood sugar levels.
• The body’s homeostatic mechanisms work to maintain the internal environment within a narrow range of values. When the environment changes, the body’s homeostatic mechanisms work to restore the internal environment to its set point. For example, when the body’s temperature rises, the homeostatic mechanisms work to cool the body down. When the body’s temperature falls, the homeostatic mechanisms work to warm the body up.
• The body’s homeostatic mechanisms are controlled by a number of hormones and neurotransmitters. These hormones and neurotransmitters include insulin, glucagon, epinephrine, norepinephrine, and serotonin. The hypothalamus is also responsible for controlling the body’s homeostatic mechanisms.

Mechanisms of Homeostasis

• There are four mechanisms of homeostasis that work together to maintain equilibrium in the body: negative feedback, receptor cells, hormones, and the autonomic nervous system.
• Negative feedback is the process by which the body monitors and adjusts its internal environment to maintain equilibrium. For example, when the body’s temperature rises, the hypothalamus releases a hormone called thermostat which signals the muscles to sweat. The sweat evaporates, cooling the body. This is an example of negative feedback because the body’s response (sweating) reduces the stimulus (the increase in body temperature).
• Receptor cells are specialized cells that monitor the body’s internal environment. They detect changes in the environment and send signals to the brain to activate the appropriate response.
• Hormones are chemicals that are released by the endocrine glands. They travel through the blood to the target organs, where they bind to receptor cells and activate the appropriate response.
• The autonomic nervous system is the part of the nervous system that controls the body’s involuntary functions, such as heart rate, breathing, and digestion. It regulates the activities of the other mechanisms of homeostasis to maintain equilibrium.

 

• In biology, homeostasis is the tendency of an organism or cell to maintain a stable internal environment. It is the maintenance of a balance by physiological or biochemical processes. The term was coined in 1854 by the French physiologist Claude Bernard. Claude Bernard’s definition of homeostasis: “A stable condition of equilibrium in which the internal environment of the body is maintained despite external fluctuations.”
• The body has many mechanisms that work together to maintain homeostasis. One of the most important is the autonomic nervous system. The autonomic nervous system controls all of the involuntary activities in the body, such as heart rate, digestion, and respiration. It has two branches, the sympathetic and the parasympathetic nervous systems. The sympathetic nervous system is responsible for the “fight or flight” response, while the parasympathetic nervous system is responsible for the “rest and digest” response.
• Another important mechanism for maintaining homeostasis is the endocrine system. The endocrine system is made up of glands that secrete hormones into the bloodstream. Hormones are chemicals that control the activities of cells and organs. The endocrine system regulates many important functions, such as growth, metabolism, and reproduction.
• The body also has a number of feedback mechanisms that help to maintain homeostasis. Feedback mechanisms are processes that monitor the internal environment and adjust the activities of the body to keep it in balance. For example, the body has a feedback mechanism for regulating blood sugar levels. The feedback mechanism consists of a network of sensors that monitor the level of sugar in the blood. When the level of sugar gets too high, the sensors send a signal to the pancreas, which secretes insulin. Insulin causes the cells to take up sugar from the blood, which lowers the blood sugar level.
• The body’s mechanisms for maintaining homeostasis are very complex. They involve the autonomic nervous system, the endocrine system, and a number of feedback mechanisms. These mechanisms work together to keep the body in balance.

Positive feedback

• Positive feedback is an important aspect of homeostasis, which is the process that maintains a stable internal environment in an organism. The body’s internal environment is constantly changing in response to the demands of the environment and the activities of the organism. Homeostasis is maintained by a series of negative feedback loops, which involve the regulated release of hormones and other chemicals.
• Positive feedback is a type of feedback that amplifies a process, instead of reversing it. In a negative feedback loop, a change in the environment or the activity of the organism triggers a response that counteracts the change. For example, the release of the hormone insulin in response to high levels of blood sugar helps to bring blood sugar levels back down. In a positive feedback loop, the response instead reinforces the original change. For example, the release of the hormone oxytocin in response to childbirth causes the uterus to contract, which helps to expel the baby.
• Positive feedback is crucial for the body’s response to emergencies, such as childbirth or a heart attack. In these situations, a rapid and strong response is needed to counteract the emergency. The positive feedback loops in the body help to produce a rapid and strong response, without which the body would be unable to maintain homeostasis.

Negative feedback

• A negative feedback loop is a regulatory mechanism that maintains the stability of a system by reducing or preventing deviations from a desired state. The homeostatic mechanisms of the body rely on negative feedback loops to maintain a steady state. For example, the body maintains a constant temperature by regulating the amount of heat energy produced and released. When the body temperature rises, the hypothalamus produces a signal that triggers the muscles to sweat. The sweat evaporates, which cools the body. This negative feedback loop reduces the body temperature until it is back within the desired range.
• A negative feedback loop can also be used to maintain a constant level of a chemical in the body. For example, the hormone insulin is released by the pancreas in response to rising levels of blood sugar. The insulin binds to receptors on the cells and stimulates the cells to take up sugar from the blood. This reduces the level of sugar in the blood, which in turn reduces the amount of insulin that is needed. This negative feedback loop keeps the level of sugar in the blood within a desired range.