topic 6 control of heart rate

Question 1

what does it mean if the heartbeat is myogenic?

Answer 1

contraction of the heart muscle originates in the heart itself, not stimulated by nerves or hormones

Question 2

what is systole?

Answer 2

heart contraction

Question 3

what is diastole?

Answer 3

heart relaxation

Question 4

what controls the regular beating of the heart?

Answer 4

cardiac muscle

Question 5

how does cardiac muscle control the beating of the heart? (stages)

Answer 5

SAN releases a wave of depolarisation across the atria, which causes it to contract
AVN releases another wave of depolarisation once the first has reached it
non-conductive collagen tissue between the atria and ventricles prevents the wave of depolarisation travelling down to the ventricles
bundle of His conducts the wave of depolarisatin down the septum and Pukryne fibres
apex and walls of the ventricles contract- short delay whilst AVN transmits the second wave allowing enough time for the atria to pump all the blood into the ventricles
cells repolarise and the cardiac muscle relaxes

Question 6

what is the bundle of His?

Answer 6

group of muscle fibres responsible for conducting waves of electrical activity between the ventricles and bottom of heart

Question 7

what is the Purkyne tissue?

Answer 7

finer muscle fibres in the right and left ventricle walls

Question 8

what does the sinoatrial node do?

Answer 8

generates electrical impulses that cause the cardiac muscles to contract, known as the pacemaker

Question 9

where is the rate that the SAN fires controlled by?

Answer 9

medulla oblongata

Question 10

what are baroreceptors?

Answer 10

pressure receptors

Question 11

where are baroreceptors found?

Answer 11

in the aorta and carotid arteries

Question 12

what are baroreceptors stimulated by?

Answer 12

high and low blood pressure

Question 13

what are chemoreceptors?

Answer 13

chemical receptors

Question 14

where are chemoreceptors found?

Answer 14

the aorta, carotid arteries and the medulla

Question 15

what do chemoreceptors respond to?

Answer 15

oxygen level in blood

as well as carbon dioxide and pH

Question 16

what are electrical impulses from receptors passed onto the medulla by?

Answer 16

sensory neurons

Question 17

what does the medulla do once it has processed information?

Answer 17

sends impulses to the SAN along sympathetic or parasympathetic neurons

Question 18

how does the heart respond to high blood pressure?

Answer 18

baroreceptors detect high blood pressure

impulses sent to the medulla, sends impulses along parasympathetic neurons, these secrete acetylcholine which binds to receptors on the SAN

effector is the cardiac muscles and the heart rate slows down to reduce blood pressure back to normal

Question 19

how does the heart respond to low blood pressure?

Answer 19

baroreceptors detect low blood pressure

impulses sent along the medulla, which sends impulses along sympathetic neurons, these secrete noradrenaline which binds to receptors on the SAN

effector is the cardiac muscles and the heart rate speeds up to increase blood pressure back to normal

Question 20

how does the heart respond to high oxygen/low CO2/high pH levels?

Answer 20

chemoreceptors detect chemical changes in the blood

impulses sent to the medulla which sends impulses along parasympathetic neurons, these secrete acetylcholine which binds to receptors on the SAN

effector is the cardiac muscles and the heart rate decreases to return levels to normal

Question 21

how does the heart respond to low oxygen/high CO2/low pH levels?

Answer 21

chemoreceptors detect chemical changes in the blood

impulses are sent to the medulla, which sends impulses along sympathetic neurons, these secrete noradrenaline which binds to receptors on the SAN

effector is the cardia muscles, heart rate increases to return levels back to normal

Question 22

where are baroreceptors found?

Answer 22

in the aorta and cartoid arteries

Question 23

where are chemoreceptors found?

Answer 23

in the aorta, cartoid arteries and medulla