Cardiac cycle COPY

Question 1

What are the exchange vessels?

Answer 1

Capillaries

Question 2

What are the capacitance vessels?

Answer 2

Veins

Question 3

What is the function of capacitance vessels?

Answer 3

Act as stores of blood

enable changes in amount of blood pumped around the body as demand changes

Question 4

What are the resistance vessels?

Answer 4

Arterioles, precapillary sphincters

Question 5

What is the function of resistance vessels?

Answer 5

Restrict blood flow in tissues which are easy to perfuse

to drive blood flow to tissues that are more difficult to perfuse

Question 6

How does the cardiac output of the right side of the heart compare to the left side of the heart?

Answer 6

They’re equal

Question 7

What is systole?

Answer 7

Contraction and ejection of blood from ventricles

Question 8

What is diastole?

Answer 8

Relaxation and filling of ventricles

Question 9

What is the pressure in the left atrium?

Answer 9

8-10mmHg

Question 10

What is the pressure in the LV?

Answer 10

120/10mmHg

Question 11

What is the pressure in the aorta?

Answer 11

120/80mmHg

Question 12

What is the pressure in the right atrium?

Answer 12

0-4mmHg

Question 13

What is the pressure in the RV?

Answer 13

25/4mmHg

Question 14

What is the pressure in the pulmonary artery?

Answer 14

25/10mmHg

Question 15

How do the pressures of the systemic and pulmonary circulations compare to each other?

Answer 15

Systemic circulation at high pressure

Pulmonary circulation at low pressure

Question 16

What is stroke volume?

Answer 16

Amount of blood ejected from the LV per heart beat

Question 17

What is the average stroke volume?

Answer 17

70ml

Question 18

At a heart rate of 70bpm, what is the cardiac output? What is the signifiance of this?

Answer 18

5L/min

Equivalent to blood volume in body

Question 19

What is the arrangement of heart muscle?

Answer 19

Like the figure 8

Question 20

Which valves are tricuspid - have three cusps?

Answer 20

Aortic valve
Pulmonary valve
Tricuspid valve

Question 21

Which valve is bicuspid - has two cusps?

Answer 21

Mitral valve

Question 22

What do the cusps of the mitral and tricuspid valves attach to? Via what?

Answer 22

Attach to papillary muscles

via chordae tendinae

Question 23

What is the function of the papillary muscles and chordae tendinae?

Answer 23

Prevent inversion of valves during systole

Question 24

What are the phases of the cardiac cycle?

Answer 24

Atrial contraction
Isovolumetric contraction
Rapid ejection
Reduced ejection
Isovolumetric relaxation
Rapid filling
Reduced filling

Question 25

Which phases form diastole?

Answer 25

Isovolumetric relaxation Rapid filling Reduced filling Atrial contraction

Question 26

Which phases form systole?

Answer 26

Isovolumetric contraction Rapid ejection Reduced ejection

Question 27

If the cardiac cycle is 0.9s long, how long is systole? How long is diastole?

Answer 27

Systole = 0.35s Diastole = 0.55s

Question 28

What is heart rate?

Answer 28

Number of cardiac cycles per minute

Question 29

A change in heart rate is accommodated by change in duration of systole or diastole?

Answer 29

Diastole

Question 30

What is a Wiggers diagram?

Answer 30

Shows changes in pressure, volume, electrical activity, sound during the cardiac cycle

Question 31

How does a Wiggers diagram of the right side of th eheart compare to that of the left side of the heart?

Answer 31

Very similar | except right side is at lower pressures

Question 32

What happens in atrial contraction?

Answer 32

P wave on ECG - atrial depolarisation A wave - increase in atrial pressure Ventricular volume increases to EDV

Question 33

Atrial contraction accounts for what percentage of ventricular filling?

Answer 33

10%

Question 34

What is EDV?

Answer 34

End diastolic volume | Volume in left ventricle at end of diastole

Question 35

What is the average EDV?

Answer 35

120ml

Question 36

What happens in isovolumetric contraction?

Answer 36

Ventricular pressure increases - ventricle contracting C wave - atrial pressure increases due to closure of mitral valve QRS complex in ECG - ventricular depolarisation S1 sound - closure of mitral valve (tricuspid valve too)

Question 37

Why is it called isovolumetric?

Answer 37

Both valves are closed | no change in volume of blood in left ventricle

Question 38

What happens in rapid ejection?

Answer 38

Ventricular pressure increases - ventricle contracting Aortic valve opens - ventricular pressure exceeds aortic pressure Aortic pressure increases - filling with blood from ventricle X descent - atrial pressure decreases as base pulled down Ventricular volume decreases - ventricle ejecting blood into aorta

Question 39

What happens in reduced ejection?

Answer 39

Ventricular pressure decreases - repolarisation of ventricle Aortic pressure decreases - less filling with blood from ventricle V wave - atrial pressure increases as it fills with blood ESV - end systolic volume, volume of blood in ventricles at end of systole T wave on ECG - ventricular repolarisation

Question 40

What hapens in isovolumetric relaxation?

Answer 40

Ventricular pressure decreases - ventricles relax Aortic valve closes - aortic pressure exceeds ventricular pressure, backflow of blood, valve closes Dicrotic notch - increase in aortic pressure, walls of aorta pulled inwards as valve closes S2 sound - aortic valve closure (pulmonary valve too)

Question 41

What is the average ESV?

Answer 41

40ml

Question 42

How is stroke volume calculated?

Answer 42

SV = EDV - ESV

Question 43

What happens in rapid filling?

Answer 43

Mitral valve opens - atrial pressure exceeds ventricular pressure Y descent - atrial pressure decreases as it empties of blood Ventricular volume - increases as ventricle fills with blood from atria S3 sound - ventricular filling

Question 44

How does blood fill the ventricles from the atria?

Answer 44

Passively

Question 45

When is the S3 sound normal? When is it a sign of pathology?

Answer 45

Normal in children Sign of pathology in adults

Question 46

What happens in reduced filling?

Answer 46

Diastasis - ventricules reach their max. relaxed volume, 90% of EDV

Question 47

How do the walls of the right and left ventricles compare to each other? Why?

Answer 47

Left ventricle has thicker wall than right ventricle | because it needs to withstand higher pressures