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PPE Revision > CVS > Flashcards

CVS Flashcards

1
Q

What is the rate of diffusion limited by?

A

Area available for exchange Diffusion resistance - nature of barrier and molecules, path length Concentration gradient

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2
Q

What is capacitance?

A

Ability to cope with changes in cardiac output - a store of blood

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3
Q

Define flow

A

Volume of fluid passing a particular point per unit time Flow = volume/time (L/min-1)

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4
Q

Define velocity

A

The rate of movement of fluid particles along the tube Velocity = distance/time (m/min-1)

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5
Q

What is laminar flow?

A

Gradient of velocity from the middle to the edge of a vessel. Velocity is highest in the centre, fluid is stationary at edge

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6
Q

What is turbulent flow?

A

Velocity gradient breaks down due to increased mean velocity. Fluid tumbles over, increasing flow resistance

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7
Q

What is viscosity?

A

Extent to which fluid layers resist sliding over one another

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8
Q

What is the equation for resistance?

A

Resistance = Pressure/Flow

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9
Q

If flow is fixed, how does pressure change if resistance is increased?

A

Increase in pressure

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10
Q

If pressure is fixed, how does flow change if resistance is increased?

A

Decrease in flow

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11
Q

What is systolic pressure?

A

Maximum arterial pressure

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12
Q

What is systolic pressure affected by?

A

Heart contractility Total peripheral resistance Compliance of arteries

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13
Q

What is diastolic pressure?

A

Minimum arterial pressure

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14
Q

What is diastolic pressure affected by?

A

Systolic pressure Total peripheral resistance

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15
Q

What is pulse pressure?

A

Difference between systolic and diastolic pressure

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16
Q

What is equation to work our average arterial pressure?

A

= 2/3 diastolic pressure + 1/3 systolic pressure

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17
Q

Define total peripheral resistance

A

Sum of the resistance of all the peripheral vasculature in systemic circulation

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18
Q

What is the dicrotic notch?

A

Occurs when left ventricular pressure falls below aortic pressure and there is a subsequent backflow of blood closing aortic value

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19
Q

What is the dicrotic wave?

A

Occurs as the aortic valve closes causing a slight increase in pressure and blood recoils off valve

20
Q

How do arteries act to reduce arterial pressure flucuations in systole and diastole?

A

They have distensible walls allowing them to stretch in systole so pressure does not change that much

21
Q

How do arterioles act as resistance vessels?

A

Walls contain smooth muscle and state of contraction determines lumen diameter

22
Q

What is vasomotor tone?

A

Smooth muscle does not actively relax so even under maximum flow there is always some vasoconstriction. This continuous contraction is vasomotor tone. Vasodilation is actually a reduction in vasconstriction

23
Q

How do vasodilator metabolites modify vasomotor activity?

A

Metabolically active tissues produce vasodilator metabolites which cause relaxation of local smooth muscle.

24
Q

State the vasodilator metabolites

A

H+ K+ Adenosine

25
Q

What occurs in reactive hyperaemia?

A

When circulation is cut off from a organ or limb for a short period, the organ/limb continues metabolising so when blood flow is restored the local arterioles dilate maximally and flow is very high.

26
Q

What is auto-regulation in relation to blood flow?

A

At most levels of metabolic activity most organs can automatically take the blood flow that they need, as long as arterial pressure is kept within certain range

27
Q

Define central venous pressure

A

The pressure in the great veins supplying the heart

28
Q

Define venous return

A

The rate of flow of blood back to the heart - limits cardiac output

29
Q

Define pre-load

A

End diastolic stretch of myocardium. Determined by venous pressure

30
Q

Define after-load

A

Force necessary to expel blood into arteries. Determined by systemic vascular resistance and ventricular wall tension

31
Q

Define contractility

A

The stroke volume for a given venous pressure. Slope of the Starling Curve

32
Q

What happens to cardiac output if venous pressure rises?

A

Cardiac output rises

Increased pre-load

33
Q

What happens to cardiac output when venous pressure falls?

A

Cardiac output falls

Decreased pre-load

34
Q

What happens to cardiac output when arterial pressure rises?

A

Cardiac output falls

Increased afterload

35
Q

What happens to cardiac output when arterial pressure falls?

A

Cardiac output increases

Decreased afterload

36
Q

Describe what happens to CVS system after eating a meal

A
  1. Increased activity of gut leads to release of metabolites = local vasodilation
  2. Causes decrease in TPR =
    • Fall in arterial pressure = baroreceptors = increased HR via sympathetic activation = increased cardiac output
    • Rise of venous pressure = increased pre-load = increased contractility = increased cardiac output
  3. Increased cardiac output decreases venous pressure and increases arterial pressure
37
Q

What is the difference between NSTEMI and STEMI

A
  • NSTEMI - Infarct is not full thickness of myocardium
  • STEMI - full thickness of myocardium
38
Q

What is acute coronary syndrome?

A
  • Group of symptoms attributed to the obstruction of coronary arteries
  • Includes STEMI, NSTEMI, unstable angina
39
Q

What is a pathological Q wave?

A
  • Deepened Q wave
  • Indicated previous MI
40
Q

Define heart failure

A

Heart failure is a state in which the heart fails to maintain cardiac output to meet metabolic need of the body despite an adequate filling pressure.

  • Heart can no longer produce same amount of force for given level of filling
41
Q

List some causes of heart failure

A
  • Ischaemic heart disease
  • Hypertension
  • Dilated cardiomyopathy - infections, drugs, pregnancy
  • Valvular heart disease
  • Arrhythmia
42
Q

List compensary mechanisms activated in heart failure

A
  1. Sympathetic nervous system - baroreceptors detecting low pressure
    • Increases HR, contractility
    • Vasoconstriction
  2. RAAS - decreased renal perfusion
    • ATII causes vasoconstriction
    • Aldosterone and ADH increases Na/H2O reabsorption
  3. Myocardial hypertrophy and remodelling
43
Q

What are the types of shock? Give an cause for that type of shock

A
  1. Cardiogenic shock - inability of heart to eject enough blood (ischaemic cardiac damage, heart failure, arrhythmias)
  2. Mechanical shock - restriction on heart of the filling of the heart (cardiac tamponade) or obstruction to flow through lungs (PE)
  3. Hypovolaemic shock - loss of circulating volume (haemorrhage, burns)
  4. Norovolaemic (distributive) shock - fall in peripheral resistance (sepsis, anaphylaxis)
44
Q

What are the acyanotic heart defects?

A

All those where left side pressure > right side pressure

  1. Atrial septal defect
  2. Patent foramen ovale
  3. Ventricular septal defect
  4. Patent ductus arteriosus
  5. Coarctation of aorta
45
Q

What are the cyanotic heart defects?

A
  1. Tetralogy of Fallot - placing outflow portion of interventricular spetum too far in anterior and cephalad direction
  2. Tricuspid atresia - no development of tricuspid valve
  3. Transposition of great arteries - results in two unconnected parallel circulations
46
Q

What is tetralogy of fallot?

A

Placing outflow portion of interventricular septum too far in anterior and cephalad direction

  1. Pulmonary stenosis
  2. Right ventricular hypertrophy
  3. Overriding aorta
  4. Ventricular septum defect
47
Q
A

PPE Revision (16 decks)

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