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CARDIO & RESPIRATORY - BRS > Cardiorespiratory Mechanics :) > Flashcards

Cardiorespiratory Mechanics :) Flashcards

1
Q

what is laminar blood flow?

A

where velocity of the fluid is constant at any point, and flows in layers

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2
Q

where is laminar blood flow the fastest?

A

closest to the lumen

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3
Q

what is turbulent blood flow?

A

when blood flows erratically, forming eddys, and is prone to pooling

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4
Q

what changes is turbulent blood flow linked to?

A

pathological changes to the endothelial lining of blood vessels

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5
Q

what pressure differences causes inspiration?

A

Pressure of atmosphere > Pressure of alveoli

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6
Q

what pressure differences causes expiration?

A

pressure of atmosphere < pressure of alveoli

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7
Q

define compliance

A

tendency to distort under pressure

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8
Q

define elastance

A

tendency to recoil to its original volume

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9
Q

what is blood pressure the same as

A

mean arterial pressure

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10
Q

state the equation for blood pressure

A

Blood pressure (MAP) = Cardiac Output x Resistance

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11
Q

state the equation to calculate pulse pressure

A

pulse pressure = systolic blood presssure - diastolic blood pressure

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12
Q

state the equation for cardiac output

A

cardiac output = stroke volume x heart rate

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13
Q

state the equation for cardiac output

A

cardiac output = stroke volume x heart rate

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14
Q

state the equation for mean arteriole pressure

A

diastolic blood pressure - 1/3 (pulse pressure)

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15
Q

define airway transmural pressure

A

the pressure difference between the alveolar pressure and intrapleural pressure

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16
Q

define intrapleural pressure

A

pressure within pleural cavity

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17
Q

state the equation for compliance

A

Compliance = change in volume / change in pressure

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18
Q

state the equation for elastance

A

Elastance = change in pressure / change in volume

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19
Q

define perfusion

A

the passage of bodily fluids i.e blood through a system to an organ or tissue

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20
Q

what is the 2 key elements of the Law of Leplace?

A

the tension on the wall of a sphere is the product of the pressure x radius of the chamber
tension inversely proportional to thickness of wall

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21
Q

what initiates rapid ejection in the cardiac cycle

A

the opening of the aortic and pulmonary valves

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22
Q

what does fluid and air flow according to?

A

pressure gradient

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23
Q

state the poiseuille’s law equation

A
* N = fluid viscousity * L = length of the tube * R = inner radius of the tube
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24
Q

if you half the radius in poiseuille’s law what happens to flow

A

flow decreases 16 times

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25
Q

what is resistance inversely proportional to?

A

resistance => inversely proportional to r(to the power of 4)

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26
Q

in what generation does resistance in the lung peak?

A

generation 4

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27
Q

why does resistance begin to decrease after generation 4?

A

number of aiways start to cumulatively increase

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28
Q

what happens do the airways as the lung volume increases?

A

airways dilate

29
Q

what increases the conductivity of airways

A

increasing lung volume

30
Q

what component of arteries and arterioles regulate diameters and resistance to blood flow?

A

smooth muscle in walls

31
Q

which out of arteries and veins acts as a reservoir for blood volume in body?

A

veins

32
Q

why do we see a fall in pressure across circulation?

A

falls due to viscous (frictional) pressure losses

33
Q

when arteries/arterioles are smaller, what happens to the resistance to flow?

A

resistance to flow increases

34
Q

why is pulmonary circulation at a lower blood pressure than systemic circulation?

A

pulmonary circuit has a smaller distance

35
Q

what does TPR stand for

A

total peripheral resistance

36
Q

Blood pressure (MAP) = Cardiac Output x Resistance: what are some assumptions for this equation? (3)

A
  1. steady flow
  2. rigid vessels
  3. right arterial pressure is negligble
37
Q

how is the regulation of blood flow achieved?

A

through resistance variation in vessels with a constant blood pressure

38
Q

state 3 variables that increase resistance of a tube

A
  1. fluid viscousity (n,eta)
  2. the length of the tube (L)
  3. inner radius of the tube (r)
39
Q

state the 2 types of blood flow

A
  1. turbulent
  2. laminar
40
Q

how does blood pressure cuff deflation lead us to hear blood flow?

A

slow deflation of cuff causes turbulent flow => can be heard by stethoscope

41
Q

at what speed does ventricular pressure fall when the aortic valve closes

A

rapidly

42
Q

at what speed does aortic pressure fall when the aortic valve closes

A

slowly

43
Q

why does aortic pressure fall slowly after the closing of the aortic valve?

A

the aorta and large arteries have elastic tissue = act as buffer to change pulse pressure

44
Q

why is the large extrapulmonary airways supported with cartilage?

A

prevents airway collapsing in the case of -ve transmural pressure

45
Q

state 2 structural properties of lung tissue

A

compliance
elastance

46
Q

how does arterial compliance lead to continuous blood flow with controlled pressure? (stages)

A

blood enters artery => artery stretches => artery recoils in diastole but due to the stretch alongside aortic valve => artery becomes a reservoir for generating diastolic blood flow => continuous blood flow with controlled pressure

47
Q

what will a decrease in arterial pressure impact and what will happen to blood pressure?

A

impact on diastolic blood flow => increase in blood pressure

48
Q

what is a pulse?

A

the difference between systolic and diastolic blood pressure

49
Q

state 2 pumps essential for venous return

A
  1. skeletal muscle pump
  2. respiratory pump
50
Q

how does the skeletal muscle pump work in terms of venous return?

A

when muscles contract => squeezing veins due to valves it pushes blood upwards => when muscles relax it creates a negative pressure sucking blood forward

51
Q

how does the respiratory pump work in terms of venous return?

A

diaphragm pulls down (-ve intrathoracic pressure => air flow) => hypercompliant veins dilate in presence of negative pressure => helping suck blood back into chest from head neck and abdomen

52
Q

state 2 health problems that can impact venous return

A
  1. incompetent valves => dilated superficial veins in leg => varicose veins
  2. prolonged elevation of venous pressure = oedema
53
Q

what is the pathology of aneurysmal disease?

A

vascular aneurysms = increase vessel radius => the inward force exerted by muscular wall must increase => if elastic muscle fibres weakened => force needed not produced => aneurysm expands until it ruptures

54
Q

what happens to vessel walls over time

A

weaken

55
Q

what does compliance depend on

A

vessel elasticity

56
Q

at low pressure, which is higher venous or arterial compliance?

A

venous (as veins hold 70% of blood)

57
Q

what is the link between compliance, transmural pressure and vessel volume?

A

Compliance = relationship between transmural pressure and vessel volume

58
Q

how does venous compliance work and aid with storage of blood?

A

Increased smooth muscle contraction => decreased venous volume => increased venous pressure => changes in venous pressure distend (swell) veins and increase the volume of blood stored in them.

59
Q

where are the air pockets smaller in the lung?

A

at the apex

60
Q

does the apex of the lung need more or less air flow than the top of the lung

A

less

61
Q

are ventilation and perfusion greater at the top or bottom of the lung?

A

bottom

62
Q

why is there less ventilation at the top of the lung?

A

Pressure of the Pleural cavity = more -ve => greater transmural pressure gradient => also Alveoli are larger and less compliant => less ventilation

63
Q

why is there more ventilation at the apex of the lung?

A

Pressure of the Pleural cavity = less -ve => smaller transmural pressure gradient => alveoli are also smaller and more compliant => more ventilation

64
Q

why is perfusion lower at the top of the lung?

A

Lower intravascular pressure => less recruitment => greater resistance => lower flow rate

65
Q

why is perfusion greater at the apex of the lung?

A

Higher intravascular pressure (gravity effect) => more recruitment => higher flow rate

66
Q

why does the difference in ventilation between the apex and base of the lung vary more than perfusion?

A

perfusion involves liquid => heavily impacted by gravity

67
Q

where is the maximum efficiency on the ventilation-perfusion graph?

A

When ventilation-perfusion crosses => ventilation-perfusion = 1

68
Q

when there is no gravity, is there a preferred perfusion location?

A

no

CARDIO & RESPIRATORY - BRS (28 decks)

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