Cardiac Cycle

Question 1

What are the layers of the heart?

Answer 1

Fibrous pericardium
Parietal pericardium (serous)
Fluid (prevent friction)
Visceral pericardium (serous)
Myocardium (heart cells)
Endocardium (inner most layer, in contact with blood)

Question 2

Which layers are on the outside of the heart & on the heart?

Answer 2

Outside heart:
Fibrous pericardium
Parietal pericardium (serous)
Fluid (prevent friction)

On heart:
Visceral pericardium (serous)
Myocardium (heart cells)
Endocardium (inner most layer, in contact with blood)

Question 3

What happens in systole & how long is it?

Answer 3

Ventricular contract & blood ejection

0.3 secs

Question 4

What happens in diastole & how long is it?

Answer 4

Ventricular relaxation & blood filling

0.5 secs

Question 5

How long does each cardiac cycle last?

Answer 5

0.8s

Question 6

What is a normal heart rate?

Answer 6

72 beats per min

Question 7

What are the 6 stages of the cardiac cycle?

Answer 7

Systole:
Isovolumetric contraction
Ejection

Diastole:
Isovolumentic relaxation 
Rapid inflow
Diastasis
Atrial systole

Question 8

What happens in isovolumetric contraction?

Answer 8

Ventricles contract, all valves shut

Increased ventricular pressure

Question 9

What happens in ejection?

Answer 9

Ventricular pressure is greater than aortic pressure
Aortic & pulmonary valve opens
Blood flows out of ventricle into arteries
Only 2/3 pumped out ~ 1/3 remains

Question 10

What happens in isovolumetric relaxation?

Answer 10

Ventricles relax, all valves shut
Volume is constant
Decrease in ventricular pressure (below aortic)

Question 11

What happens in rapid inflow?

Answer 11

Pressure (atria) > pressure (ventricles)
So atrioventricular valves open, blood flows from atria to ventricles
Down a pressure gradient - passive
80% ventricles full

Question 12

What happens in diastasis?

Answer 12

Pressure between atrium and ventricle begin to equalize
Pressure gradient decreases
Passive filling rate decreases

Question 13

What happens in atrial systole?

Answer 13

Contraction of atria to fully empty into ventricles

Question 14

How many heart sounds are there?

Answer 14

3

Question 15

What are the 3 heart sounds?

Answer 15

Low pitched (lubb) - atrioventricular Valve shutting

Louder (dubb) - aortic and pulmonary valves close

Third is sounds of blood rushing into left ventricle

Question 16

Blood vessel autoregulation is…..

Answer 16

Intrinsic and extrinsic/myogenic

Question 17

What is intrinsic autoregulation?

Answer 17

When arterioles either vasocontrict/dilate in a response to changes in resistance
Maintain constant blood flow

Question 18

What is myogenic/extrinsic autoregulation?

Answer 18

When blood flow is increased and stretches vascular smooth muscle
Muscle automatically constricts until diameter is normalized/ slightly reduced

Question 19

What is hyperemia?

And the two types?

Answer 19

Increase in blood flow

Active and reactive

Question 20

Describe active hyperemia?

Answer 20

Increase in blood flow when metabolic activity increases (eg exercise)

Question 21

Describe reactive hyperemia?

Answer 21

Blood supply to tissue is occluded, after occlusion removed, increased blood flow to it