control heart rate

Question 1

caridac muscle myogenic

Answer 1

contract and relax without receiving signals from nerves

Question 2

process

Answer 2

1. sinoatrial node SAN (wall of right atrium)
2. sends waves of electrical activity to atria walls
3. atria contract at same time
4. non conductive collagen tissude seperates atria and ventricle
5. waves transferred to atrioventricular node AVN
6. pass electrical activity onto bundle of His - slight delay ensuring atria have emptied
7. bundle splits into purkyne tissue (bottom of left and right ventricle
8. carries electrical activity into walls - right and left ventricle contract simultaneously from bottom up

Question 3

rate controlled by

Answer 3

part of brain medulla oblongata

Question 4

pressure receptors

Answer 4

baroreceptors
aorta carotid arteries
stimulated by high and low blood pressure

Question 5

chemical receptors

Answer 5

chemoreceptors
aorta, carotid arteries, medulla
monitor O2 in blood and CO2 and PH (indicators of O2 level)

Question 6

impuls sent

Answer 6

sensory neurones -> medulla (process) -> impulse to SAN along sympathetic (action) or parasympathetic (calm) neurone

Question 7

stimulus

high blood pressure

Answer 7

detect by baroreceptors
parasympathetic neurones
secrete acetylcholine which bind to receptors on SAN
heart rate slows to reduce BP

Question 8

stimulus

low blood pressure

Answer 8

baroreceptors
sympathetic neurones
secrete noradrenaline binds to receptors on SAN
heart rate increase to increase BP

Question 9

stimulus

high O2 / low CO2 / high PH

Answer 9

chemoreceptors 
parasympathetic neurone 
secrete acetyl choline 
bind to receptors SAN 
heart rate decrease return levels to normal

Question 10

stimulus

low O2 / high CO2/ low PH

Answer 10

chemoreceptors 
sympathetic neurone 
secrete noradrenaline 
bind to receptors SAN 
heart rate increases to return to normal levels