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Physiology 1 > Haemodynamics > Flashcards

Haemodynamics Flashcards

1
Q

What is haemodynamics? [1 mark]

A

The relationship between blood flow, blood pressure and resistance to flow.

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2
Q

What is Darcy’s law? [2 marks]

A
  • It describes the rate at which a fluid flows through a permeable medium
  • Considers the role of pressure energy in flow
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3
Q

What is the formula for Darcy’s law? [3 marks]

A

Flow (Q) = (Pressure difference between arteries and veins)/Resistance to flow

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4
Q

What is Bernoulli’s law? [2 marks]

A
  • States that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure/potential energy
  • Considers the role of pressure, kinetic and potential energy in flow
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5
Q

What can explain blood moving against the pressure gradient? [1 mark

A

Bernoulli’s law

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6
Q

What is the formula for Bernoulli’s law? [4 marks[

A

Flow = Pressure (PV) +Kinetic ((ρV^2)/2) + Potential (ρgh)

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7
Q

What is blood flow? [1 mark]

A

The volume of blood flowing in a given time (ml/min).

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8
Q

What is perfusion? [1 ark]

A

The blood flow per given mass of tissue (ml/min/g).

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9
Q

What is velocity of blood flow affected by? [2 marks]

A
  • Cross sectional area
  • Smaller CS = faster velocity
    (and vice versa)
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10
Q

What is the formula for volume flow [3 marks]

A

Volume flow (Q) = Velocity (V) x Cross sectional area (A)

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11
Q

What happens in laminar blood flow? [5 marks]

A
  • Smooth flow
  • Friction between H2O molecules and blood vessels
  • Concentric shells
  • Zero velocity at walls
  • Max. velocity at the centre
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12
Q

What does laminar blood flow do to RBCs and blood? [2 marks]

A
  • Moves RBCs to the centre

- Speeds up blood flow

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13
Q

Where does laminar blood flow occur? [2 mars]

A
  • Arteries and arterioles

- Veins and venules

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14
Q

What happens in turbulent blood flow? [2 marks]

A
  • Blood does not flow linearly and smoothly in adjacent layers.
  • There are whirlpools, eddies, vortices.
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15
Q

What causes turbulent blood flow? [2 marks]

A
  • Increased pressure
  • Increased velocity
    (due to obstruction)
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16
Q

Where can you get turbulent blood flow? [3 marks]

A
  • Ventricles at mixing
  • Aorta at its peak flow
  • Atheroma (plaque that cause bruits)
17
Q

What happens in bolus blood flow? [3 marks]

A
  • Uniform velocity
  • Little internal friction
  • Very low resistance
18
Q

What happens to RBCs in bolus blood flow? [3 marks]

A
  • RBC are larger than capillaries
  • So they move in single file
  • Plasma columns are trapped between RBC
19
Q

Where does bolus blood flow occur? [1 mark]

A

Capillaries

20
Q

What does Reynold’s number tell us? [2 marks]

A
  • When flow changes from lumbar to turbulent

- At around 1000-2000

21
Q

What is the formula for Reynold’s number? [3 marks]

A

Re=ρVD/μ

Re = (density x velocity x diameter)/viscosity

22
Q

Why is the systolic pressure not 0? [1 marks]

A

Arteries keep expanding and contracting

23
Q

What factors affect arterial blood pressure? [4 marks]

A
  • Cardiac output (SV, HR) – increases it
  • Properties of arteries
  • Peripheral resistance
  • Blood viscosity
24
Q

What is pulse pressure? [2 marks]

A
  • The difference between diastolic and systolic pressures.

- Tells you about the stroke volume and arterial compliance

25
Q

What is the dicrotic notch? [1 mark]

A

Closure of aortic valves

26
Q

What is the formula for pulse pressure? [3 marks]

A

Pulse pressure = (Stroke volume)/compliance

27
Q

What is compliance? [1 mark]

A

A measure of how easily the heart can be distended

28
Q

What happens in decreased compliance? [3 marks]

A
  • Systolic and pulse pressure increase disproportionally
  • Because aorta can’t stretch anymore
  • Afterload increases
29
Q

What diseases can arise from decreased arterial compliance? [2 marks]

A
  • Strokes

- Aneurysms

30
Q

What is the formula for compliance? [3 marks]

A

Compliance = (Change in volume)/(Change in pressure)
OR
Pulse pressure = (Stroke volume)/compliance

31
Q

What can cause decreased arterial compliance? [2 marks]

A
  • Old age (stiff arteries)

- Obesity

32
Q

How do you find the mean blood pressure? [3 marks]

A

Diastolic pressure + 1/3(pulse pressure)

33
Q

What controls mean blood pressure? [9 marks]

A
  • Age
  • Disease
  • Distance along arterial tree
  • Blood volume - SV, CO
  • Exercise - SV, CO
  • Emotion - stress, anger, fear, apprehension, pain
  • Wake/sleep - low BP 80/50 mmHg
34
Q

What is the pulse pressure like at the aorta? [1 mark]

A

Small

35
Q

What happens to pulse pressure as you go down the arterial tree? [2 marks]

A
  • Increases slightly

- Vessels become less compliant

Physiology 1 (13 decks)

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