CVS Physiology

Question 1

Flow at rest

Answer 1

5L/min

Question 2

What are the resistance vessels?

Answer 2

Arterioles

Question 3

Why doesnt cardiac muscle exhibit tetanus

Answer 3

Long action all potential and refractory period

Question 4

What causes the pacemaker potential of SA node

Answer 4

influx of calcium via L-type calcium channel and effluent (flowing out) of potassium

Question 5

What activates the SA node beta 1 receptor?

Answer 5

Sympathetic noradrenaline and circulation adrenaline from adrenal medulla —> tachycardia

Question 6

What activates the SA muscarinic receptors?

Answer 6

Acetylcholine from parasympathetic vagus nerve —> bradycardia

Question 7

Which vessels affect preload

Answer 7

Capacitance vessels

Question 8

What vessels affect afterload

Answer 8

Arterioles

Question 9

What effect does increased TPR have on aortic pressure? How does this affect SV

Answer 9

Increased aortic pressure —> increased SV

Question 10

What is the typical end systolic volume

Answer 10

60ml

Question 11

Formula for cardiac output

Answer 11

CO = HR x SV

Question 12

Where is blood velocity highest/lowest

Answer 12

Highest = aorta and vena cava

Slowest in capillaries

Question 13

What impact does skeletal muscle pump and respiratory pump have on venous return

Answer 13

Increased venous return

Question 14

Where would you find continuos capillaries, fenestrated capillaries, discontinuous capillaries

Answer 14

continuos capillaries - brain
fenestrated capillaries - kidney, intestine
discontinuous capillaries - liver

Question 15

What effect does osmotic pressure and hydrostatic pressure have on capillaries

Answer 15

Osmotic draws water in

Hydrostatic pushes water out (via plasma proteins - hyperproteinaemia —> oedema)

Question 16

Formula for MAP

Answer 16

CO x TPR

Question 17

What is active hyperaemia and pressure auto regulation

Answer 17

Active hyperaemia = build up of metabolites leads to EDRF release —> vasodilation

Pressure auto regulation = decrease in perfusion pressure leads to EDRF release —> vasodilation

Question 18

What is the central MAP mechanisms

Answer 18

sympathetic nerves release noradrenaline and bind

to alpha 1 receptors to constrict arterioles and decrease flow to increase TPR and MAP

Question 19

Which receptors detect BP

Answer 19

Aortic arch baroreceptors and internal carotid artery baroreceptors

Question 20

What is the Valsalva manoeuvre? What does it assess?

Answer 20

forced expiration against a closed glottis, can use to assess a patients baroreceptor reflex

Question 21

What would happen to BPM if sympathetic and parasympathetic innervation was cut to heart

Answer 21

increase resting heart rate, as the SA node has an intrinsic rhythm of approximately 100bpm