Session 2

Question 1

Left atrioventricular valve?

Answer 1

mitral/bicuspid

Question 2

Right atrioventricular valve?

Answer 2

tricuspid

Question 3

Left Outflow valve?

Answer 3

aortic

Question 4

Right outflow valve?

Answer 4

Pulmonary

Question 5

Which ion enters cell during action potential?

Answer 5

calcium

Question 6

Length of action potential/systole?

Answer 6

280ms

Question 7

What do pacemakers do?

Answer 7

generate an action potential at regular intervals

Question 8

What is the spread of excitation

Answer 8

SAN (right atrium) -> atria (atrial systole) -> AVN (120ms delay) -> septum -> ventricular myocardium from endocardium to epicardial surface (contraction from apex up)

Question 9

When does the left ventricle open and close?

Answer 9

Intra-ventricular pressure exceeds aortic pressure (closes when aortic pressure>intra-ventricular pressure

Question 10

The cardiac cycle - start?

Answer 10

(end of ventricular systole)
Ventricles contracted
ventricular pressure high, outflow valves open
blood flowing into arteries
A/V valve closed

Question 11

The cardiac cycle - 2

Answer 11

Ventricles relax
ventricular pressure falls
brief backflow closes valves
all valves closed
"isovolumentric relaxation"

Question 12

The cardiac cycle - 3

Answer 12

During systole, blood has continued to return to atria
Atrial pressure high
ventricular pressure falls below atrial pressure
AV valves open

Question 13

The cardiac cycle - 4

Answer 13

With the A/V valves open -

ventricles fill rapidly (rapid filling phase ~ 200-300ms)

Question 14

The cardiac cycle - 5

Answer 14

Diastole continues - ventricles fill more slowly
Ventricular pressure rises as ventricular walls stretch
When ventricular pressure equals atrial pressure, filling stops

Question 15

The cardiac cycle - 6

Answer 15

Atrial systole
Forces a small extra amount of blood into ventricles
(heart can still function without atrial systole)

Question 16

The cardiac cycle - 7

Answer 16

Ventricular systole
ventricular pressure rises very rapidly
exceeds atrial pressure
after brief backflow, AV valves close
all valves closed
"isovolumetric contraction"

Question 17

The cardiac cycle - 8

Answer 17

Ventricular pressure rises very rapidly

outflow valves open

Question 18

The cardiac cycle – 9

Answer 18

Blood is ejected into the arteries (rapid ejection phase)

Arterial pressure rises rapidly

Question 19

The cardiac cycle - 10

Answer 19

As arterial pressure rises
Rate of ejection of blood falls
outflow ceases with blood still in ventricle

Question 20

The cardiac cycle - 11

Answer 20

systole ends

Question 21

Heart sounds? (2)

Answer 21

‘lup’ closure of A/V valves
‘dup’ closure of outflow valves
interval between sounds -280ms
interval to next - 700ms

Question 22

Cardiac Output?

Answer 22

Stroke volume x heart rate = cardiac output /l.min-1