Regulation of HR and SV

Question 1

Sympathetic nerves release

Answer 1

noradrenaline

Question 2

noradrenaline and adrenaline both act on

Answer 2

b1 receptors in the SA node

Question 3

Noradrenaline acting on B1 receptors in the SA node leads to

Answer 3

an increase in heart rate

tachycardia

Question 4

parasympathetic NS releases ….. form the …..

Answer 4

ACh

Vagus nerve

Question 5

ACh acts on muscarinic receptors on the

Answer 5

SA node

Question 6

ACh acting on the SA node will

Answer 6

decrease heart rate

bradycardia

Question 7

Bradycardia

Answer 7

decreased HR

Question 8

Tachycardia

Answer 8

increased HR

Question 9

Starling law states that the energy of contraction is proportional to the

Answer 9

initial length of the cardiac muscle fibre

Question 10

Preload

Answer 10

initial stretching of cardiomyocytes before contraction

Question 11

Stroke volume

Answer 11

volume of blood from left ventricle in one beat

Question 12

In vivo, afterload is set by the

Answer 12

arterial pressure against which the blood is expelled

Question 13

If Total peripheral resistance increases, then stroke volume will

Answer 13

decrease

Question 14

after load is the

Answer 14

load against which the muscle tries to contract

Question 15

capacitance vessels (veins and venules) affect

Answer 15

preload

Question 16

resistance vessels (arterioles) affect

Answer 16

AFTERLOAD

Question 17

adrenaline is released form the

Answer 17

adrenal medulla

Question 18

adrenaline and noradrenaline act on SV by

Answer 18

increasing contractility

gives stronger but shorter contraction

Question 19

Parasympathetic system effects on SV

Answer 19

very little

Question 20

Cardiac Output equation

Answer 20

CO = HR x SV

Question 21

Increasing HR with an electronic pacemaker causes a small increase in CO but then decreases SV. Why?

Answer 21

shortened cardiac interval cuts into the rapid filling phase

Question 22

reduced EDV will reduce

Answer 22

preload

and therefore SV

Question 23

HR increases by

Answer 23

decreased vagal tone

increased sympathetic tone

Question 24

contractility increases by

Answer 24

increased sympathetic tone

Question 25

Venous return increases via

Answer 25

venoconstriction