topic 9

Question 1

homeostasis

Answer 1

maintenance of a sate of dynamic equilibrium

Question 2

negative feedback - body temperature decreases

Answer 2

1. optimum temp
2. you start shivering
3. respiration occurs
4. temperature will rise

Question 3

negative feedback - body temperature increases

Answer 3

1. optimum temp
2. person sweats
3. evaporation of sweat from skin surface
4. temperature drops

Question 4

positive feedback

Answer 4

1. normal level
2. normal level change
3. receptors detect the change
4. communication with CNS or hormonal system
5. effector response

Question 5

cardiac output

Answer 5

cardiac volume x heart rate

Question 6

what are baroreceptors

Answer 6

• on the aorta, they control heart rate during exercise
  
  • found in sinuses in carotid arteries

Question 7

what happens during exercise - adrenaline during exercise

Answer 7

released in anticipation of exercise
- during exercise vasodilation occurs so bp drops
- reduced stretch on baroreceptors
- cardiac control centre send signals along sympathetic nerve to increase bp by vasoconstriction

Question 8

what happens when exercise stops

Answer 8

• bp in arteries increases
  
  • baroreceptors are stretched (very fast hr)
  • more sensory nerve impulses go to the cardiac centre
  • impulses then go to parasympathetic system to slow down hr
  • blood vessels widen
  • bp reduced

Question 9

what are chemoreceptors

Answer 9

special nerve cells or receptors that sense changes in the chemical composition of the blood

Question 10

what is the cardiac control centre

Answer 10

• located in the medulla oblangata of the brain
• controls the heart rate + blood pressure through hormones + nerve impulses

Question 11

what are chemoreceptors sensitive to

Answer 11

CO2
- as CO2 levels go up, pH level in blood goes down

Question 12

what happens when aortic and carotid receptors detect the change in pH levels

Answer 12

• they send impulses along sensory neurons to the cardiac control centre in medulla
• increased impulses travelling down sympathetic nerve to heart
• so, HR increased so blood flow to lungs increases and more CO2 is removed from blood

Question 13

what happens as CO2 levels fall

Answer 13

pH levels rises
- chemoreceptors send less impulses