Systemic Circulation and Hemodynamics Flashcards Preview

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Flashcards in Systemic Circulation and Hemodynamics Deck (80)
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1
Q

Arteries have ____ flow and ____ pressures

A

HIGH

2
Q

Arterioles can moderate pressure because they have a lot of ____ in their walls

A

Smooth muscle

3
Q

Capillaries have what important quality?

A

LARGE cross-sectional area

4
Q

Veins have ____ flow and ____ pressures

A

LOW

5
Q

Veins have what important quality?

A

Act as a storage reservoir; LARGE volume

6
Q

What is the equation for Flow (Q)?

A

Pressure gradient/Resistance

7
Q

If you increase resistance, what effect will that have on the flow?

A

DECREASE flow

8
Q

If you decrease resistance, what effect will that have on the flow?

A

INCREASE flow

9
Q

Resistance is directly proportional to what?

A

Viscosity

10
Q

If you increase viscosity you will do what to resistance?

A

INCREASE

11
Q

Resistance is indirectly proportional to what?

A

Radius (diameter) of the vessel

12
Q

If you increase the radius of a vessel you will do what to resistance?

A

DECREASE

13
Q

If you increase the radius of a vessel, what effect will that have on the flow?

A

Increased radius = decreased resistance = increased flow

14
Q

If you decrease the radius of a vessel, what effect will that have on the flow?

A

Decreased radius = increased resistance = decreased flow

15
Q

Ratio of RBC:plasma in the blood

A

Hematocrit

16
Q

Increased hematocrit increases ____

A

Viscosity

17
Q

Increased viscosity will increase?

A

Resistance

– and thus decrease flow

18
Q

Hematocrit is usually around 40-50% and is higher in what gender?

A

Males

19
Q

Adding resistance beds in series ____ resistance

A

INCREASES

20
Q

Adding resistance beds in parallel _____ resistance

A

DECREASES

21
Q

How are capillary beds arranged, in series or parallel and what is the corresponding resistance?

A

They are arranged in parallel = low resistance

22
Q

Flow is the same as?

A

Cardiac output

23
Q

What is the equation for Cardiac Output (flow)?

A

Arterial pressure - Venous pressure / TPR

24
Q

TPR

A

Total Peripheral Resistance

25
Q

Where is the site of greatest control of blood flow and TPR?

A

Arterioles!!

26
Q

Increased Sympathetic tone does what to TPR and flow?

A

Vasoconstriction

- INCREASED TPR and DECREASED flow

27
Q

Decreased Sympathetic tone does what to TPR and flow?

A

Vasodilation

- DECREASED TPR and INCREASED flow

28
Q

What is the equation for Velocity?

A

Flow / Cross-sectional Area

29
Q

Where will velocity be high?

A

Arteries

30
Q

Where will velocity be low?

A

Capillaries - due to the HIGH CSA!

31
Q

When velocity is HIGH the blood flow may become ___

A

Turbulent

32
Q

What predicts when turbulence will occur?

A

Reynold’s Number

33
Q

Reynold’s Number has to be greater than what to predict the transition from laminar to turbulent flow?

A

> 2000

34
Q

Reynold’s Number of > 2000 may lead to?

A

Bruits and Arteriosclerosis

35
Q

What is compliance?

A

Ability to relax and hold blood – opposite of elasticity

36
Q

Where is compliance the highest?

A

Veins

37
Q

Where is compliance the lowest?

A

Arteries - HIGH elasticity

38
Q

Smooth muscle contraction in veins increases blood flow back to arteries and increases?

A

Blood pressure

39
Q

Pressure gradually ____ through systemic circulation

A

Decreases

40
Q

Where is the greatest pressure drop in the systemic circulation?

A

Arterioles

41
Q

Pulse pressure

A

Systolic BP - Diastolic BP

42
Q

Mean Arterial Pressure

A

1/3(systolic BP) + 2/3(diastolic BP)

43
Q

Compliance equation

A

Stroke volume / Pulse pressure

44
Q

Decreased compliance has what effect on the pulse pressure and thus the systolic BP?

A

Increased pulse pressure and systolic BP

45
Q

Capillaries have ____ that can further control flow

A

Precapillary sphincters

46
Q

What are 3 ways exchange across capillary walls occurs?

A
  1. Clefts - water soluble substances
  2. Plasma membrane - lipid soluble substances
  3. Vesicles - larger substances
47
Q

Vasomotion

A

Oscillating flow of blood through capillaries

– Not all capillaries are open all the time

48
Q

What regulates vasomotion of capillaries?

A

Oxygen levels in tissues

49
Q

Fluid moving out of a capillary is known as?

A

Filtration

50
Q

Filtration at a capillary has what sign?

A

+

51
Q

Fluid moving in to a capillary is known as?

A

Absorption

52
Q

Absorption at a capillary has what sign?

A

-

53
Q

What are the 2 types of pressures involved at the capillary

A

Hydrostatic

Osmotic

54
Q

Where does fluid usually leave the capillary (+)?

A

Arteriolar end

55
Q

Where does fluid usually enter the capillary (-)?

A

Venous end

56
Q

Capillary hydrostatic pressure (Pc)

A

Forces fluid OUT of capillary

57
Q

Capillary osmotic pressure (PIEc)

A

Draws fluid IN to capillary

58
Q

Interstitial hydrostatic fluid pressure (Pif)

A

Forces fluid IN to capillary

59
Q

Interstitial osmotic pressure (PIEif)

A

Pulls fluid OUT of capillary into interstitial fluid

60
Q

What is the equation to determine the net direction of fluid movement at the capillary?

A

(Pc - Pif) - (PIEc - PIEif)
= + –> Fluid leaves capillary (filtration)
= - –> Fluid enters capillary (absorption)

61
Q

What takes up things that the capillaries cannot reabsorb?

A

Lymphatics

62
Q

Acute control of blood flow is achieved by rapid changes in local vasodilation/constriction of?

A

Arterioles
Metarterioles
Precapillary sphincters

63
Q

Blood flow changes due to changes in arterial pressure than then return to normal blood flow

A

Autoregulation

64
Q

What 2 theories are involved in autoregulation?

A

Metabolic

Myogenic

65
Q

Metabolic theory

A

Increased arterial pressure = excess flow provides too much oxygen and nutrients

66
Q

What are associated with the metabolic theory?

A

Reactive and Active hyperemia

67
Q

Occurs after blood supply was blocked for a short time

A

Reactive hyperemia

68
Q

Occurs when tissue metabolic rate is increased

A

Active hyperemia

69
Q

Myogenic theory

A

Increased arterial pressure = smooth muscle walls stretch and then constrict to return blood flow back to normal

70
Q

List some (4) humoral vasoconstrictors

A

Norepinephrine
Vasopressin
Angiotensin 2
Serotonin

71
Q

List some (2) humoral vasodilators

A

Bradykinin

Histamine

72
Q

Most ions vasodilate except for?

A

Calcium

73
Q

Coronary blood flow is restricted during?

A

Ventricular contraction

74
Q

Cerebral blood flow is not influenced by?

A

Vasoactive substances

75
Q

Where are the highest pressures in pulmonary circulation?

A

Right ventricle and pulmonary artery

76
Q

At rest, skeletal muscle is under what control?

A

Central and baroreceptor

77
Q

At exercise, skeletal muscle is under what control?

A

Local

- Contraction periods of occlusion following by reactive hyperemia

78
Q

What is inhibited to induce vasodilation and get blood to the skin?

A

Central sympathetic activation

79
Q

Trauma to the skin releases?

A

Histamine

80
Q

Histamine on the skin causes?

A

Red line
Red flare
Wheal (edema)