9.8 control of heart rate in mammals

Question 1

where is the cardiac control center located?

Answer 1

medulla oblongata

Question 2

what are baroreceptors?

Answer 2

stretch receptors

Question 3

where are baroreceptors found?

Answer 3

wall of internal carotid artery and aorta

Question 4

what happens when the heart is beating too fast?

Answer 4

1- there is a change in the pressure in the aorta and the carotid arteries
2- this causes change in the extent to which the elastic and muscle fibres are stretched
3- impulse is sent to the cardiac control center in the medulla oblongata
4- if pressure is too high impulse is sent down the vagus nerve
5- acetylcholine is released which has an inhibitory effect and slows down the heart rate
6- opens K+ channels which slows the firing of the SAN

Question 5

what happens when the heart is beating too slow?

Answer 5

1- there is a change in the pressure in the aorta and the carotid arteries
2- this causes change in the extent to which the elastic and muscle fibres are stretched
3- impulse is sent to the cardiac control center in the medulla oblongata
4- impulse is sent down the cardiac nerve to SAN
5- noradrenaline is released which causes increase in heart rate

Question 6

what do chemoreceptors do?

Answer 6

they are sentisitve to the levels of carbon dioxide in the blood (CO2 goes up pH goes down)