KA6- Cardiac Cycle

Question 1

1) The auto-rhythmic cells of… , located… , set… 28

Answer 1

the sino-atrial node (SAN) or pacemaker, located in the wall of the right atrium, set the rate at which the heart contracts

Question 2

2) The timing of… controlled by… causing … 21

Answer 2

cardiac muscle cell contraction is controlled by impulses from the SAN spreading through the atria causing atrial systole

Question 3

3) Control of … and… and… —>located… 25

Answer 3

contraction and timing by cells of the SAN and transmission to the atrio-ventricular node (AVN) —> located in the centre of the heart

Question 4

4) Impulses from the AVN… then up… causing… 25

Answer 4

travel down fibres in the central wall of the heart then up through the walls of the ventricles causing ventricular systole

Question 5

1) The medulla regulates… through… 19

Answer 5

the rate of the sino-atrial node through the antagonistic action of the autonomic nervous system

Question 6

2) A sympathetic nerve… which… 10

Answer 6

releases noradrenaline which increases the heart rate

Question 7

3) A parasympathetic nerve… which.. 10

Answer 7

releases acetylcholine which decreases the heart rate