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Flashcards in GP Dr as teacher cardio questions Deck (51)
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1
Q

How long does a single heartbeat last?

A

0.8 seconds

2
Q

How long does diastolic last for in a heartbeat?

How long does systolic last for in a heartbeat?

A
  • 0.5s

- 0.3s

3
Q

What are the 4 stages of the cardiac cycle?

A

1) Passive filling
2) Atrial contraction
3) Ventricular ejection
4) Isovolumetric ventricular relaxation

4
Q

What is the pressure in atria + ventricles during passive filling?

A

Close to 0

5
Q

What is the pressure in the aorta during passive filling?

A

80mmHg

6
Q

What % of ventricular filling is due to passive filling?

A

80%

7
Q

What on an ECG marks atrial contraction?

A

Between the P and QRS complex

8
Q

What % of ventricular filling occurs due to atrial contraction?

A

20%

9
Q

What is the normal end diastolic volume (after passive filling + atrial contraction)

A

130ml

10
Q

What happens when ventricular pressure exceeds atrial pressure?

A

AV valves (tricuspid + mitral) shit

11
Q

What is the 1st heart sound due to?

A

Closure of the AV valves

12
Q

At the time of the 1st heart sound, is the aortic valve open/closed?

A

It is STILL closed at time of 1st heart sound

13
Q

What is isovolumetric contraction (i.e. of the ventricles)?

A
  • when all 4 heart valves are shut and tension (pressure) within the ventricles rise
    (increase in tension around a CLOSED VOLUME)
14
Q

What stage on an ECG marks ventricular contraction?

A

After the QRS complex (between S and T)

15
Q

What happens when ventricular pressure exceeds aortic/pulmonary pressure?

A
  • aortic/Po valves open
16
Q

When the aortic/Po valves open is this a loud/silent event?

A

silent

17
Q

What is end stroke volume (ESV)?

A
  • the volume of blood left behind in each ventricle once stroke volume has been ejected (upon opening of aortic + Po valves)
18
Q

What is the normal ESV?

A

~65ml

19
Q

How do you calculate SV (vol ejected by ventricle per heartbeat)?

A

SV = EDV - ESV

20
Q

What is a normal SV?

A

~ 70ml (130-65)

21
Q

What happens to the aortic pressure upon opening of aortic/Po valves

A

Aortic pressure rises

22
Q

What on the ECG represents ventricular repolarisation?

A

T wave

23
Q

What happens to the ventricles upon repolarisation?

A

Pressure falls

Ventricles relax

24
Q

What happens when ventricular pressure is less than aortic pressure?

A

Aortic/Po valves shut

25
Q

What produces a 2nd heart sound?

A

Closure of aortic/Po valves

26
Q

What is a DICROTIC NOTCH?

A

The vibration of the aortic valves upon closure creates a little rise in the aortic pressure curve

27
Q

What is isovolumetric ventricular relaxation?

A

Once the aortic/Po valves close, the pressure within the ventricles falls in a CLOSED BOX (all 4 valves are closed)
(tension falls around a closed volume)

28
Q

What happens when ventricular pressure < atrial pressure?

A

AV valves open

-silent event

29
Q

What happens when AV valves open?

A

Beginning of passive filling

NEW CARDIAC CYCLE

30
Q

What is central venous pressure?

A

Measure of pressure of central veins close to heart?

31
Q

What does JVP measure?

A

Indication of right atrial pressure

RA pressure gives us an idea of what the central venous pressure is

32
Q

What are the names of the 3 letters when measuring JVP?

A

a, c, v

33
Q

On a JVP meausrement, what do the following letters represent?

  • a
  • c
  • v
A

a) rise in JVP as atria contract
c) rise in JVP as tricuspid valve bulges into atrium during ventricular contraction
v) increase in JVP during atrial filling - release as AV valves open

34
Q

What % of total body weight is water? (i.e. in a 70kg person)?

A

60% (42L)

35
Q

What fraction of body water is

a) extracellular?
b) intracellular?

A

a) 1/3 (14L)

b) 2/3 (28L)

36
Q

Of extracellular water, what % of it is:

a) Plasma?
b) interstitial?

A

a) 25% (3L)

b) 75% (11L)

37
Q

What is interstitial fluid?

A

Water that bathes body cells

- acts as a go between blood + body cells

38
Q

Why is blood flow slow through the capillary bed?

A
  • to increase time for gas/nutrient exchange
39
Q

What regulates flow of blood through the capillary bed in MOST tissues?

A

TERMINAL ARTERIOLES

40
Q

What regulates flow of blood through capillary beds in SOME tissues (e.g. mesentery)

A

Pre-capillary sphincter

41
Q

In a capillary, what do water filled pores in the membrane permit?

A
  • movement of WATER SOLUBLE SUBSTANCES

- e.g ions/glucose/Amino acids

42
Q

In a capillary, what is moved across the membrane by VESICULAR TRANSPORT?

A
  • EXCHANGEABLE PROTEINS

- e.g hormones

43
Q

How do lipid soluble substances (e.g. GASES) diffuse through capillary membranes?

A
  • by diffusion across endothelial membrane
44
Q

Can plasma proteins pass in/out of capillaries through the endothelial wall?
Give an example of a plasma protein

A
  • NO: STAY INTRAVASCULAR

Albumin; plasma proteins are produced by the liver

45
Q

What is BULK MOVEMENT/

A
  • in capillaries, fluid movement follows a pressure gradient
46
Q

What law (from rest physiology) does the movement of gases/solutes in and out of capillaries follow?

A
  • FICK’S LAW OF DIFFUSION

- Diffusion across a sheet is proportional to surface area but inversely proportional to thickness

47
Q

What is transcapillary fluid flow?

A

Flow of fluid is passively driven by PRESSURE GRADIENTS ACROSS CAPILLARY WALL

48
Q

What is ultra-filtration?

A
  • exchange across capillary wall is essentially PROTEIN FREE PLASMA
49
Q

How do you calculate net filtration pressure?

A

forces favouring filtration - forces opposing filtration

50
Q

What is a filtration coefficient and what does it do?

A
  • relates to permeability of wall to fluid

- also affects NET FILTRATION PRESSURE

51
Q

What 2 things calculate net filtration pressure?

A

1) forces favouring filtration - forces opposing filtration

2) filtration coefficient (permeability of wall to fluid)