CVS Physiology 3- The cardiac cycle

Question 1

What is the cardiac cycle?

Answer 1

The sequence of pressure and volume changes that takes place during cardiac activity

Question 2

What are the mechanical events brought about by?

Answer 2

The rhythmic changes in cardiac electrical activity

Question 3

The cardiac cycle consists of alternate periods of what?

Answer 3

Systole

Diastole

Question 4

At rest, is diastole or systole longer in duration?

Answer 4

Diastole

Question 5

What valves are known as the semilunar valves?

Answer 5

Aortic and pulmonary

Question 6

When pressure is gretaer behind the valve, what happens?

Answer 6

Valve opens

Question 7

When pressure is greater in front of the valve, what happen?

Answer 7

Valve closes

Does not open in opposite direction

Question 8

What is an ECG a record of?

Answer 8

The overall spread of electrical activity through the heart

Question 9

What can be described at mid-diastole?

Answer 9

Atrial and ventricular pressures low
Ventricles contain ~80% of final filled volume
Aortic and pulmonary valves closed
Aortic pressure high

Question 10

What can be described at late diastole?

Answer 10

P wave of ECG occurs
Towards end of P wave atria contract- increasing arterial pressure-most of the blood in the atria is propelled into ventricles
Small increase in ventricular pressure

Question 11

What can be described at End of diastole/early systole?

Answer 11

QRS complex of ECG begins- start of ventricular depolarisation
Ventricles contract at end of QRS complex- early systole
Rapid increase of ventricular pressure

Question 12

During early systole, AV valves snap shut, this causes what?

Answer 12

First heart sound

Ventricles contrat but both AV and aortic valves are shut- noblood can enter or leave

Question 13

What can be described at the ejection period?

Answer 13

Ventricular pressure exceeds arterial pressure - aortic and valve pulmonary valves open
Blood is ejected into the aorta and pulmonary artery
Aortic pressure rises

Question 14

What can be desribed at the end of ventricular systole?

Answer 14

T wave signals ventricular depolarisation

Ventricles start to relax- ventricular pressure falls below aortic pressure-aortic valves shuts

Question 15

What causes the second heart sound in the end of the ventricular systole?

Answer 15

When the aortic vlaves shut again

and Dicrotic notch (incisura) on aortic pressure record

Question 16

What can be described at the filling period?

Answer 16

Ventricular pressure falls below atrial pressure
AV valves open
Major part of ventricular filling
blood which entered atria during ventricular systole is released into ventricles by opening of AV valves
Atrial and ventricular pressures fall sharply and ventricular volume increases rapidly

Question 17

Name the 5 phases of the cardiac cycle and what ones are ventricular filling or ventricular emptying

Answer 17

Ventricular Filling:

• Passive filling during ventricular and atrial diastole
• Atrial contraction
• Isovolumetric ventricular contraction

Ventricular Emptying:

• Ventricular ejection
• Isovolumetric ventricular relaxation

Question 18

How are the heart sounds generated?

Answer 18

Heart action

Question 19

How can heart sounds be detected?

Answer 19

Phonocardiogram

Question 20

What are the two distinct heart sounds?

Answer 20

1st-Coincides with the begining of systole- produced bby the closure of the AV valves

2nd-Begins with the onset of diastole-closure of the aortic and pulmonary (semilunar) valves

Question 21

What are abnormal sounds in pathological conditions called?

Answer 21

Murmurs