CR: PBL 2 (Heart and Exercise) Flashcards Preview

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Flashcards in CR: PBL 2 (Heart and Exercise) Deck (42):
1

Define pulse pressure

Systolic BP - Diastolic BP (difference)

2

Define mean arterial pressure

Arithmetic mean of arterial blood pressure (CO x TPR)

3

Define pre-load

Pressure of blood in the ventricle before contraction

4

What is central venous pressure?

Pressure of blood in the great veins as they enter the right atrium

5

Define venous return

The volume of blood returning to the right atrium in one minute

6

Define total peripheral resistance

Resistance to the flow of blood in the whole system (MAP/CO)

7

Define systemic vascular resistance

Resistance to blood flow offered by all of the systemic vasculature (not pulmonary) - (MAP - RA pressure)/CO

8

Define 'ejection fraction'

Proportion of EDV which is ejected by contraction

9

What is meant by 'central command'

The anticipatory response of the autonomic nervous system to exercise which causes CO and arteriole adjustment

10

How does the cardiovascular system respond to exercise immediately?

Local chemicals cause arteriole dilation (lactic acid, nitric oxide and increased CO2, H+ and K+ levels)

11

How does the autonomic nervous system respond to exercise?

Sympathetic fight or flight response initiated:
a1 receptor --> causes blood shunting from digestion
B1 receptor --> increases HR and contraction force (SV)
B2 --> bronchodilation

12

Why does heart rate change after exercise?

Increased sympathetic stimulation to SAN

13

Why does systolic blood pressure change after exercise?

Greater volume of blood in ventricles due to increased venous return --> exerts greater pressure on arterial walls in systole

14

Why does diastolic blood pressure change after exercise?

Decreases due to vasodilation to the actively respiring muscles/tissues

15

Why does stroke volume change after exercise?

Starling's law - greater distension of ventricular sarcomere with increased preload --> greater contraction --> greater volume of blood ejected in one beat

16

How do you calculate mean arterial blood pressure?

1/3(pulse pressure) + diastolic BP
OR CO x TPR

17

How may mean arterial pressure values be indicative of ischaemia?

MAP is considered to represent perfusion pressure, so less than 65mmHg may be indicative of ischaemia

18

What are normal BP values?

Systolic: Below 120mmHg
Diastolic: Below 80mmHg

19

What are normal HR values?

60-100bpm

20

What are normal stroke volume values?

70ml

21

What are normal cardiac output values?

4.9-5.6 L/min

22

What are normal pulse pressure values?

40mmHg

23

What are normal mean arterial pressure values?

65-110mmHg

24

Why doesn't MAP change after exercise?

Despite increased cardiac output, there is vasodilation of muscles which counteracts increased pressure

25

Why does pulse pressure increase after exercise?

Due to increased difference in blood pressures (systolic up, diastolic down)

26

What factors affect heart rate?

autonomic innervation, hormones, fitness and age

27

What factors affect stroke volume?

Heart size, fitness, gender, contractility, duration of contraction, preload and afterload

28

How do you calculate stroke volume?

EDV - ESV

29

How does preload affect SV and CO?

Increased preload increases SV and CO

30

How does afterload affect SV and CO?

Increased afterload (resistance) decreases SV and CO

31

Outline the Frank-Starling mechanism

Increased venous return --> increased EDV (ventricular filling) --> increased preload --> increased myocyte stretch or sarcomere --> greater recoil --> greater ejection --> greater SV and CO

32

What is a baroreceptor?

Stretch receptor

33

Where are baroreceptors found?

Aorta, carotid arteries, vena cava and atria

34

How do baroreceptors respond to an increase in stretch?

Parasympathetic stimulation increased --> decreased HR and SV --> decreased BP

35

How do baroreceptors respond to a decrease in stretch

Parasympathetic stimulation suppressed --> increase HR and SV --> increased flow and BP

36

What are chemoreceptors?

Receptors that respond to changes in chemicals such as pO2, pCO2, H+ and lactic acid

37

Where are chemoreceptors found?

CNS and by baroreceptors

38

How do chemoreceptors respond to an increase level of chemicals?

Sympathetic stimulation suppressed --> decreased HR and SV

39

How do chemoreceptors respond to a decreased level of chemicals?

Sympathetic stimulation increased --> increased HR and SV

40

What would exercise-induced hypotension indicate?

Coronary artery disease if drop of more than 10mmHg systolic BP during exercise

41

What would exercise-induced angina indicate?

Angina is severe chest pain that radiates to shoulder/arm and is due to inadequate cardiac blood supply --> coronary artery disease

42

Name the two main mechanisms blood flow to tissues can be increased during exercise

Greater stroke volume --> greater CO
Vasodilation