Principles of homeostatis and negative feedback

Question 1

What is homeostatis?

Answer 1

The maintenance of an internal environment within restricted limits in an organism

Question 2

Why is homeostatis important?

Answer 2

• enzymes are sensitive to changes in PH and in temperature. A change in PH can cause a difference in tertiary structures and result in a different active site
• Higher temperatures can denature enzymes
• A change in water potential can cause cells to shrink or burst due to water leaving or entering by osmosis
  -A constant blood glucose concentration also ensures that there is a reliable source of glucose for respiring cells

Question 3

What is negative feedback?

Answer 3

• A mechanism that restores levels to normal and returns a system to its optimum
• An example of this is controlling blood glucose levels
• Having seperate negative feedback systems that control depatures from the norm in either directions gives a greater degree of homeostatic control. This is because there are positive actions in both directions

Question 4

What is positive feedback?

Answer 4

When a deviation from optimum results in a greater deviation from normal
An example of this is when a stimulus leads to a small influx of na+ ions. This influx leads to a greater increase in the permeability of the neurone membrane, causing more na+ ions to enter.