Homeostasis

• Homeostasis - Maintaining a stable internal environment
• The conditions inside your body need to be kept steady, even when the external environment changes
• Homeostasis is really important because your cells need the right conditions in order to function properly, including the right conditions for enzyme action
• Homeostasis is all about the regulation of the conditions inside your body - and cells - to maintain a stable internal environment, in response to changes in both internal and external conditions
• You have loads of automatic control systems in your body that regulate your internal environment
• Automatic control systems include both nervous and hormonal communication systems
• There are control systems that maintain your body temperature, your blood glucose level and your water content
• All your automatic control systems are made up of 3 main components whichworrk together to maintain a steady condition - cells called receptors, coordination centres (including the brain, spinal chord and pancreas) and effectors
• Negative feedback counteracts changes
• Your automatic control systems keep your internal environment stable using a mechanism called negative feedback
• When the level of something (e.g water or temperature) gets too high or too low, your body uses negative feedback to bring it back to normal
• 1. Receptor detects a stimulus -- level is too high -> 2. The coordination centre receives and processes the information, then organises a response -> 3. Effector produces a response, which counteracts the change and restores the optimum level - the level decreases
• A stimulus is a change in the environment
• 1. Receptor detects a stimulus -- level is too low -> 2. The coordination centre receives and processes the information, then organises a response -> 3. Effector produces a response, which counteracts the change and restores the optimum level - the level increases
• The effectors will just carry on producing the responses for as long as they're stimulated by the coordination centre. This might cause the opposite problem - making the level change too much (away from the ideal)
• Luckily the receptor detects if the level becomes too different and negative feedback starts again
• Negative feedback happens without you thinking about it - it's all automatic