6.3 Control of heart rate

Question 1

what nervous system is involved with control of the heart

Answer 1

autonomic

Question 2

what is the heart muscle

Answer 2

myogenic

Question 3

what is myogenic

Answer 3

muscle can contract and relax without receiving impulses/signals from nerves
- pattern of contraction controls the regular haartbeat

Question 4

what is the sinoatrial node

Answer 4

• small mass of tissue in wall of rig he atrium

Question 6

why does the SAN do

Answer 6

• acts as pacemaker
• sets rhythm of heartbeat by sending out regular waves of electrical activity to the atrial walls

Question 7

what does the atrioventricular node do

Answer 7

passes waves of electricity onto bundle of His

Question 8

why so there a slight delay before AVN reacts

Answer 8

to make sure atria have emptied before ventricles contract

Question 9

why does SAN cause

Answer 9

atria to contract at the same time

Question 10

what is the bundle of His

Answer 10

group of muscle fibres responsible for comducting waves of electrical activity between ventricles to the apex of the heart

Question 11

what does the bundle of His breakdown into

Answer 11

muscle fibres in the left and right ventricle walls > purkyne tissue

Question 12

what does the purkyne tissue do

Answer 12

carries waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously from the bottom up

Question 13

what does SAN generate

Answer 13

electrical impulses that cause cardiac muscle to contract

Question 14

what controls the rate at which the SAN fires

Answer 14

medulla oblongata

Question 15

what are pressure receptors called

Answer 15

baroreceptors

Question 16

where are baroreceptors

Answer 16

aorta and carotid arteries

Question 17

what are chemical receptors called

Answer 17

chemoreceptors

Question 18

where are chemorecpetors

Answer 18

carotid arteries and medulla

Question 19

what do chemoreceptors monitor

Answer 19

co2 levels
o2 levels
pH lebels

Question 20

how is high blood pressure controls

Answer 20

• baroreceptors detect high blood pressure, send impulses along sensory neuron to medulla, sends impulse along parasympathetic neurons
• acetylcholine secreted, binds to receptors on SAN
• heart rate slow down, blood pressure returns to normal

Question 21

how is low blood pressure controlled

Answer 21

• baroreceptors detect low blood pressure, send impulses along sensory neuron to medulla, sends impulses along sympathetic neurons
• noradrenaline secreted, binds to receptors on SAN
• heart rate speeds up to return blood pressure to normal

Question 22

what is secreted when there’s high blood pressure

Answer 22

acetylcholine

Question 23

what is secreted when there’s low blood pressure

Answer 23

noradrenaline

Question 24

how is high blood o2, low co2, high pH controlled

Answer 24

• chemorecpetors detect chemical change in blood, sends impulses along sensory neuron to medulla, sends impulses along parasympathetic neurons
• acetylcholine secreted > binds to SAN receptors
• heart rate decreases to return levels to normal

Question 25

how is low blood o2, high co2 and low pH controlled

Answer 25

• chemoreceptors detect chemical changes, sends impulses along sensory neuron to medulla, sends impulses down sympathetic neurons
• noradrenaline secreted, binds to receptors on SAN
• heart rate increases to return levels to normal

Question 26

what is a result of increased respiration

Answer 26

low blood o2
high co2
low pH