Negative Feedback and Homeostasis Flashcards Preview

Biology A2 topic 7 > Negative Feedback and Homeostasis > Flashcards

Flashcards in Negative Feedback and Homeostasis Deck (18)
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1
Q

What is the purpose of homeostasis?

A

to maintain a stable internal environment

2
Q

What is a norm value/set point?

A

the condition that is optimal, one which attempts are made to maintain

3
Q

What is the function of a receptor?

A

to detect deviations from the norm, they send signals to effectors

4
Q

What is the funcition of effectors?

A

To restore internal conditions to the norm value/set point

5
Q

What is negative feedback?

A

a system which serves to reverse a change which has occured

6
Q

Where is the cardiovascular control centre found?

A

the medulla

7
Q

Name two receptors involved in control of the heart.

A

Stretch receptors in the muscle walls of the heart

Baroreceptors in the carotid arteries of the neck (detect pressure)

8
Q

What does the parasympathetic nervous system do?

A

slows down heart rate

9
Q

What does the sympathetic nervous system do?

A

speeds up heart rate

10
Q

What happens (to the heart rate) when excersise ends?

A
  • blood pressure increases in arteries so baroreceptors and stretched
  • they send nerve impulses to the cardiovascular control centre which send impulses through the parasympathetic system to slow down the heart rate and cause vasodilation.
  • blood pressure lowers
11
Q

What happens (to the heart rate) when exercise starts ?

A

-blood vessels dilate in response to adrenaline
blood pressure falls
- this reduces the stretch of the baroreceptors and they almost stop responding
- the cardiovascular control centre is not stimulated so it sends signals along the sympathetic system to stimulate the heart rate.
- blood pressure increases

12
Q

Where is the ventilation/respiratory centre?

A

the medulla

13
Q

describe the process of basic breathing.

A
  • impulses from the respiratory centre travel along sympathetic nerves causing the intercostal muscles an diaphram to contract
  • the lungs inflate and we inhale
  • stretch receptors on the walls of the bronchi send nerve impulses to the respiratory centre
  • these impulses cause the breathing muscles to relax so we exhale
14
Q

Name two receptors involved in the control of breathing.

A

stretch receptors on the walls of the bronchi

chemorecpetors in the aortic bodies and carotid bodies (sensitive to levels of CO2 and pH)

15
Q

What do chemoreceptors do when CO2 levels are too high?

A

send impulses to the respiratory centre which send impulses to the breathing muscles to increase breathing rate.

16
Q

Where are the two types of temperature receptors found, and why is this an advantage to us?

A

the hypothalamus
the skin

It allows for great sensitivity not only to actual changes but to potential changes too (eg, if the skin receptors are cold the body can adjust so the core temperature doesn’t drop too)

17
Q

Describe the process of vasodialtion.

A
  • sphincter muscles around the arterioles leading to the capilliaries are not stimulated to contract, so they relax
  • more blood flows to capillaries close to the air and less blood flows through shunt vessels
  • heat is lost by conduction and radiation
18
Q

Describe the process of vasoconstriction.

A
  • sphincter muscles around the arterioles leading to the capilliaries contract
  • constricts capillaries and more blood flows through the shunt vesses, further from the air
  • less heat is lost by conduction and radiation