Introduction to HOMEOSTASIS
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Suitable for GCSE/IGCSE/O level Biology/Science courses or equivalent
1. What is homeostasis? What is its function?
Negative feedback systems explained
Homeostasis is the maintenance of a stable and constant internal environment in an organism.
Homeostasis is crucial to the regulation of an internal environments and enables organisms to adapt to change, both internally and externally. Internal temperature, blood sugar levels, water level and osmotic balance are regulated by a number of organs and systems working together.
The conditions inside your body need to be kept as steady as possible even if the external conditions change. This 'steadiness' or 'regulation' of the 'right conditions' is vitally important for your cells to function properly eg the action of enzymes which control most of your bodies chemistry.
Homeostasis is how the conditions inside the body are regulated to maintain a stable internal environment in response to changes in both internal and external conditions and usually involve a negative feedback system.
Your body has numerous automatic control systems that help regulate your internal environment.
The body controls itself by means of negative feedback systems which constantly help keep conditions right for healthy sustainable life for what you might call 'normal conditions'. Basically if something in the changes beyond a certain limit, then the change is detected and the body automatically responds to balance things up again.
Cells in the body can only survive within narrow physical and chemical limits. They require a constant temperature and pH as well as a constant supply of dissolved food and water. This is why the body requires control systems that constantly monitor and adjust the composition of the blood. These control systems include receptors which sense changes and effectors that bring about changes.
(b) How do negative feedback systems work?
There are many automatic control systems in your body that control and regulate your internal environment eg the nervous system, hormone molecule communication. Other control systems 'monitor' things such as your body temperature, water content and blood glucose levels.
The table below illustrates the general principles of maintaining the ideal 'level' of something e.g. temperature, pH, carbon dioxide, blood glucose, and water via three 'components' working in conjunction with one another to keep conditions steady.
All your automatic control systems consist of three components which work together to maintain you in a steady condition:
Your automatic control systems keep your internal environment stable by means of a negative feedback mechanism so that the functions of the three sets of cells are all co-ordinated.
This is outlined below and the word 'level' means the level of anything being controlled e.g. temperature, pH, blood sugar, water contents.
Note: The coordination centre = control centre, just different phrases meaning the same thing!
This negative feedback detection system process is continuous so that there is always a small fluctuation from the 'NORMAL', illustrated by the graph below (green line ~normal).
The graph shows several decreases and increases as the negative feedback system clicks into action.
Our negative feedback systems work well if external or internal changes are small, i.e. within certain limits, BUT, if the environment (ambient conditions) change too much, then our body might not be able to counteract the enforced change.
Homeostasis notes index:
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