3.6.4.1 Homeostasis and negative feedback (Unit 6 Homeostasis)

Question 1

What is negative feedback?

Answer 1

When a change causes a response that leads to a reduction in that change (return to optimum)

Question 2

Describe the sequence of events that occur during a response to a stimulus (both hormonal and nervous)

Answer 2

Stimulus->Receptor->Coordinator->Effector->Response

Question 3

Define homeostasis.

Answer 3

The maintenance of a constant internal environment.

Question 4

Which conditions are maintained by homeostasis?

Answer 4

1. Temperature
2. Blood/tissue fluid water potential
3. Blood glucose concentration

Question 5

What is positive feedback? (give an example)

Answer 5

When a change leads to a response that leads to the amplification of that change.
Eg. childbirth, the initial contractions trigger more and stronger contractions.

Question 6

Why is it important to maintain a stable internal temperature?

Answer 6

Enzymes have optimum temperature
Above this and they denature as hydrogen and ionic bonds break
Below this they don’t have enough kinetic energy to function

Question 7

What is a hormone?

Answer 7

Hormones are released by glands
They travel in the blood
They bind to complementary receptors on specific target cells