Principles of Homeostasis & Negative Feedback

Question 1

What is homeostatis?

Answer 1

Homeostasis involves physiological control systems which maintain the internal environment with restricted limits.

Question 2

What are examples of things we control?

Answer 2

Core temperature and blood pH as they affect enzyme activity. Enzymes are important in regulating and increasing the rate of metabolic reactions.

Question 3

Why do we control temperature?

Answer 3

At low temperatures, enzyme and substrate molecules have less kinetic energy meaning the frequency of collisions between the two decreases so there is a lower rate of E-S complex formation. This slows the rate of reaction.

At high temperatures, hydrogen and ionic bonds which hold the enzyme’s tertiary structure in place get broken. This changes the tertiary structure, denaturing the enzyme preventing E-S complex formation. This slows the rate of reaction

Question 4

Why do we control blood pH?

Answer 4

Change in H+ and OH- interferes with hydrogen and ionic bonds which hold the enzyme’s tertiary structure in place. A change in the enzyme’s tertiary structure leads to the denaturation of enzymes preventing E-S complexes forming so the rate of reaction decreases.

Question 5

Why do we control blood glucose concentration?

Answer 5

The blood glucose concentration affects the water potential of blood, water may enter/leave the cell by osmosis if WP is changed, causing them to swell/shrink. If blood glucose is too low, there won’t be enough respiratory substrate available for respiration.

Question 6

What does the negative feedback loop involve?

Answer 6

A receptor detects a stimulus involved with a condition. A coordination system transfers information between different parts of the body. An effector carries out a response.

Question 7

Why do we have multiple separate negative feedback mechanisms?

Answer 7

To allow control of departures in different directions from the original state, giving a greater degree of control.

Question 8

What happens during positive feedback?

Answer 8

Effectors respond to further increase the level away from the normal level (e.g. blood clotting where platelets release chemicals which activate more platelets)