3.6.1.3 control of heart rate

Question 1

myogenic

Answer 1

when a muscle can contract and relax without receiving nerve impulses

Question 2

Location of sinoatrial node and function

Answer 2

located in the right atrium and known as the pacemaker.
releases electrical impulse across the atria causing the atria contract (atrial systole)

Question 3

Location of atrioventricular node and function

Answer 3

located at the boarder of the right and left ventricle, but found in the right atrium.
releases electrical impulses after a short delay once electrical impulse from the SA node is detected

Question 4

Location of bundle of His and function

Answer 4

runs through the septum.
passes the electrical impulse down the septum to the purkinje fibres

Question 5

Location of purkinje fibres and function

Answer 5

in the walls of the ventricles.
spread the electrical impulse from the AV node to the apex of the heart, causing the ventricles to contract (ventricular systole)

Question 6

Location of non-conductive tissue and function

Answer 6

located between atria and ventricles.
prevents electrical impulses travelling down to ventricles.
cause a short delay in ventricle systole, allowing the ventricles to fill up

Question 7

why is the short delay needed before the AV node sends an electrical impulse

Answer 7

allows enough time for atria to contract and pump blood into ventricles.
allow ventricles to fill up with blood

Question 8

role of the medulla oblongata

Answer 8

controls heart rate via the autonomic nervous system.
uses the sympathetic and parasympathetic nervous system to control SA node rhythm

Question 9

chemoreceptors - location and function

Answer 9

located in the carotid artery.
responds to change in pH or CO2

Question 10

baroreceptors - location and function

Answer 10

located in the carotid artery.
responds to pressure changes

Question 11

what is the response to a high blood pressure

Answer 11

detected by baroreceptors.
impulse sent to medulla.
greater frequency of impulses sent to the SA node via parasympathetic neurones.
releasing acetylcholine
lower frequency of impulses from SA node.
decreases heart rate

Question 12

What is the response to a low blood pressure

Answer 12

detected by baroreceptors.
impulse sent to the medulla.
more frequent impulses sent to the SA node along sympathetic neurones.
releasing noradrenaline
increases heart rate

Question 13

What is the response to a high blood pH or low CO2 conc

Answer 13

detected by chemoreceptors.
impulse sent to medulla.
greater frequency of impulses sent to the SA node via parasympathetic neurones.
releasing acetylcholine
lower frequency of impulses from SA node.
decreases heart rate so less CO2 used up, decreasing pH

Question 14

What is the response to a low blood pH or high CO2 conc

Answer 14

detected by chemorecepetors.
impulse sent to the medulla.
more frequent impulses sent to the SA node along sympathetic neurones.
releasing noradrenaline.
increases heart rate, more blood to the heart to use up CO2 increasing pH