CVS Session 2 (Lecture 2.1)

Question 1

Which valve separates the RA from the RV?

Answer 1

Tricuspid

Question 2

Which valve separates the LA from the LV?

Answer 2

Mitral

Question 3

Which valve separates the LV from the aorta and the RV from the pulmonary artery?

Answer 3

Semilunar valves

Question 4

How long is systole? How is it initiated?

Answer 4

280ms - action potential long, single contraction from an influx of Ca2+ influx.

Question 5

What are the pacemakers of the heart?

Answer 5

1) Sino-atrial node

2) Atrio-ventricular node

Question 6

What do pacemakers do?

Answer 6

Generates an action potential which spreads over the whole heart producing a coordinated contraction.

Question 7

What is diastole?

Answer 7

When the heart is at rest OR interval between beats.

Question 8

Where is the SAN located?

Answer 8

RA

Question 9

What does the SAN do and what does it cause?

Answer 9

Generates an action potential that spreads over the atria causing atrial systole.

Question 10

Where does the A.P go after atrial systole?

Answer 10

Reaches AVN where it is delayed for 120ms. Spreads down septum (via bundle of His) towards the apex.

Question 11

Where does the A.P spread next after passing down towards the apex?

Answer 11

Spreads through the ventricular myocardium from inner (endocardial) to outer (epicardial) surface.

Question 12

How does the heart contract in relation to apex?

Answer 12

Ventricle contracts from apex up, forces blood towards the outflow valves.

Question 13

How long does ventricular systole last?

Answer 13

280ms

Question 14

How long does diastole last?

Answer 14

700ms

Question 15

When do the mitral/tricuspid valve open?

Answer 15

When atrial pressure > intraventricular pressure

Question 16

When do the mitral/tricuspid valves close?

Answer 16

When atrial pressure < intraventricular pressure

Question 17

What is needed to close the inflow valves?

Answer 17

Small amount of regurgitation to close flaps

Question 18

When does the aortic valve open?

Answer 18

When left ventricular pressure > aortic pressure

Question 19

When does the aortic valve close?

Answer 19

When left ventricular pressure < aortic pressure

Question 20

What is the cardiac cycle?

Answer 20

The cardiac cycle is the sequence of pressure flow changes and valve operations that occur with each heartbeat.

Question 21

Starting at the end of systole describe the 1st part of the cardiac cycle.

Answer 21

1) Ventricles contracted
2) Intra-ventricular pressure high
3) Outflow valves open
4) Blood flows into the arteries
* Ventricular pressure > atrial so inflow A/V valves closed.

Question 22

Starting at ventricular relaxation describe the 2nd part of the cardiac cycle.

Answer 22

1) Ventricles begin to relax
2) IV pressure falls rapidly
3) IV < Aortic pressure
4) Brief backflow closes outflow valves
5) Isovolumetric relaxation (same volume)

Question 23

Starting at isovolumetric relaxation describe the 3rd part of the cardiac cycle.

Answer 23

1) Blood return to atria
2) Atrial pressure high
3) IV pressure falls below atrial pressure
4) A/V valves open

Question 24

Starting when A/V valves open, describe the 4th part of the cardiac cycle.

Answer 24

1) Rapid filling of the ventricles - rapid filling phase
2) Lasts 200-300ms
3) Majority of ventricular filling in this phase of early diastole.

Question 25

Starting at early diastole describe the 5th part of the cardiac cycle.

Answer 25

1) Diastole continues with slower rate of ventricular filling
2) IV pressure rises as ventricular wall stretches
3) Unitl IV pressure = atrial so filling stops
4) Known as diastasis

Question 26

Starting at atrial systole describe the 6th part of the cardiac cycle.

Answer 26

1) Atrial systole (SAN firing)
2) Forces small extra amount of blood into the ventricles
3) Heart can work without this phase

Question 27

Starting at ventricular systole describe the 7th part of the cardiac cycle.

Answer 27

1) Ventricular systole
2) IV pressure rises rapidly
3) Exceeds atrial pressure so brief backflow closes AV valves
4) Isovolumetric contraction

Question 28

Starting at isovolumetric contraction describe the 8th part of the cardiac cycle.

Answer 28

1) IV pressure rises rapidly until > arterial pressure
2) Arterial pressure has been falling from diastole
3) Outflow valves open

Question 29

Starting at outflow valves opening describe the 9th part of the cardiac cycle.

Answer 29

1) Outflow valves open
2) Blood is ejected into the arteries
3) Rapid ejection phase
4) Arterial pressure rises

Question 30

Starting at arterial pressure rising describe the 10th part of the cardiac cycle.

Answer 30

1) Rate of ejection of blood falls
2) Arterial + IV pressure peak towards end of systole
3) Outflow eventually caeses with blood still in ventricle

Question 31

Starting at the end of systole describe the 11th part of the cardiac cycle.

Answer 31

Systole ends and cycle repeats!

Question 32

What are the two main sounds of the heart and how do they arise?

Answer 32

1) First sound - lub - closure of a/v valves

2) Second sound - dub - closure of outflow valves

Question 33

When do the sounds arise?

Answer 33

1) First sound - onset of ventricular systole

2) Second sound - end of ventricular systole

Question 34

What is the interval between the first and second sound?

Answer 34

280 ms

Question 35

What is the interval between the second and first sound?

Answer 35

700ms at rest, can shorten upon exertion

Question 36

What would cause splitting of sounds?

Answer 36

Right and left valves not closing at the same time.

Question 37

Where would a third and fourth sound be heard? Is this normal?

Answer 37

Yes it is normal

Third sound - early in diastole
Fourth sound - atrial systole

Question 38

What generates a heart murmur? Give 2 causes.

Answer 38

Turbulent flow of blood generates murmurs.

1) Aortic stenosis - narrowed valve
2) Incompetance - valve not closing properly

Question 39

When do murmurs occur?

Answer 39

When blood flow is at its highest

Question 40

What is cardiac output?

Answer 40

The volume pumped per minute by the left heart is known as the Cardiac Output.

Question 41

What determines the C.O?

Answer 41

Heart rate and stroke volume

Question 42

What is HR and SV?

Answer 42

SV - volume ejected per cardiac cycle

HR - number of cycles per minute

Question 43

At rest what is the normal SV, HR and CO?

Answer 43

SV = 80ml
HR= 60
CO= 5L per min