Homeostasis

What is homeostasis?

Homeostasis is the physiological process that maintains a stable internal environment in living organisms despite external changes. It involves the regulation of different factors like temperature, pH, blood glucose levels, and water balance. This is all done to ensure that the body of an organism can function optimally.

How does homeostasis work?

Feedback mechanisms are a key principle of homeostasis. These mechanisms involve sensors that detect changes in the internal environment, control centres that receive and process this information, and effectors that carry out the necessary response required to restore the balance.

There are two types of feedback mechanisms: negative feedback and positive feedback.

Negative feedback loops

Negative feedback loops are the most common type of feedback loop in homeostasis. It works to counteract changes and bring the body back to its set point. For example, if body temperature rises above the set point, sensors in the skin and brain detect the increase and trigger a response to cool the body down, such as sweating and vasodilation of blood vessels in the skin.

Positive feedback

Positive feedback loops result in the opposite effect, they amplify changes and move the body further away from the set point. These types of feedback loops are less common but play important roles in certain physiological processes, such as childbirth and blood clotting. For example, during childbirth, contractions of the uterus stimulate the release of the hormone oxytocin, which in turn causes more contractions, leading to a positive feedback loop that ultimately results in the birth of the baby.

Why is homeostasis important?

Homeostasis is essential as it allows cells, tissues and organs to function optimally within an organism. It allows organisms to adapt to changes in their external environment which is essential for their survival and well-being.

What key terms do I need to know?

1. Homeostasis: The process by which living organisms maintain a stable internal environment despite changes in the external environment.
2. Set point: The level of a physiological factor that allows an organism to function optimally.
3. Sensors: Structures or cells that detect changes in the internal environment and send signals to control centres.
4. Control centres: Regions in the body, often in the brain or endocrine glands in humans, that receive and process information from sensors and initiate appropriate responses.
5. Effectors: Structures or cells that carry out the response directed by the control centre.
6. Thermoregulation: The process of regulating body temperature to maintain it within a narrow range.
7. Blood glucose regulation: The process of regulating blood glucose levels to ensure they remain within a narrow range for optimal cellular function.
8. Osmoregulation: The regulation of water intake and output to maintain appropriate levels of hydration within an organism.
9. pH regulation: The process of maintaining the optimum pH of bodily fluids, such as blood and tissue fluids, within a specific range for proper biochemical reactions.
10. Hormones: Chemical messengers that help regulate various physiological processes involved in homeostasis.
11. Negative feedback loop: The series of events in which a change in a physiological factor triggers a response that opposes or reverses the change, helping to restore homeostasis.
12. Positive feedback loop: The series of events in which a change in a physiological factor triggers a response that amplifies the change, leading to a further deviation from the set point.