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Physiology > Microcirculation > Flashcards

Microcirculation Flashcards

1
Q

Blood volume (%CO) increases blood flow to what 4 places?

A

brain. kidneys, liver, and muscle

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2
Q

Blood volume/tissue weight increases relative blood flow for what 6 places?

A

brain, kidneys, liver, heart, thyroid gland, and adrenal gland

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3
Q

When precapillary sphincters are open, blood flows to _____.

A

capillaries

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4
Q

When precapillary sphincters are closed, blood flows to ____.

A

metarterioles

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5
Q

When arteriovenous anastomosis (AVA) is open, blood passes through ______.

A

AVA

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6
Q

When arteriovenous anastomosis (AVA) is closed, blood passes through ______.

A

capillary bed

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7
Q

_____ is the intermittent blood flow through the capillaries, turning on/off every few seconds or minutes.

A

Vasomotion

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8
Q

_____ originated from altering periods of vasoconstriction and vasodilation of metarterioles and precapillary sphincters.

A

Vasomotion

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9
Q

What types of endothelial junctions do capillaries have?

A

only a few tight junctions

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10
Q

Capillary exchange is mediated by what three thing?

A

intercellular clefts
fenestrations
caveolae (plasmalemmal vesicles)

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11
Q

____ are curving channels between endothelial cells.

A

intercellular clefts

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12
Q

____ are pores within the plasma membrane.

A

fenestrations

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13
Q

True or False? Fenestrations have larger diameter than intercellular clefts

A

True

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14
Q

____ are invaginations of the plasma membrane that may coalesce to form vesicular channels all the way through the endothelial cell.

A

Caveolae

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15
Q

______ and _____ has a role in diffusion of water-soluble ions and small solutes.

A

Intercellular clefts and Fenestrations

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16
Q

_____ has a role in transcytosis of macromolecules, mainly plasma proteins, through the endothelium.

A

Caveolae

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17
Q

What can’t pass through the blood-brain barrier (BBB)?

A

most neurotransmitters and toxins and bacteria

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18
Q

Width of pores and fenestrations are smaller than albumin. Any molecule/cell larger than albumin will only pass through _____ capillaries.

A

sinusoid

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19
Q

Continuous capillaries contain _____.

A

intercellular clefts

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20
Q

Fenestrated capillaries contain _____.

A

fenestrations

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21
Q

The _____ are the Hydrostatic and Colloid Osmotic Forces that Determine whether fluid will move out of the blood into he IF or in the opposite direction.

A

four Starling forces

22
Q

Name the 4 Starling forces.

A 
Hydrostatic:
- capillary pressure
- interstitial fluid pressure
Osmotic:
- plasma colloid osmotic pressure
- interstitial fluid colloid osmotic pressure
23
Q

____ states that the fluid movement across the wall of a capillary is dependent on the balance between the hydrostatic pressure gradient and the oncotic pressure gradient across the capillary.

A

Starling’s hypothesis

24
Q

The change in _____ is the major factor responsible for the filtration-absorption along the capillary

A

hydrostatic pressure

25
Q

True or False? The change in hydrostatic pressure helps in the blood flow along the capillary.

A

True

26
Q

Filtration on the arterial side is slightly ____ than the absorption on the venous side.

A

larger

27
Q

______: the amount of fluid filtering from the arterial ends equals almost exactly the fluid by absorption.

A

Starling equilibrium

28
Q

Excess of filtration (Net fluid filtration) is the fluid that must be returned through the ______.

A

lymphatics

29
Q

What is the normal rate of net filtration in the entire body, not including the kidneys?

A

about 2 ml/min (2 L/day)

30
Q

True or False? Blood flow is regulated at the minimal level that will supply each tissue’s requirements — heart workload is kept at a minimum.

A

True

31
Q

What is the most important of the endothelial-derived relaxing factors?

A

Nitric Oxide

32
Q

____ is a lipophilic gas continually released from endothelial cells in response to a variety of chemical, physical, and mechanical stimuli (shear forces).

A

Nitric Oxide

33
Q

Endothelial-derived nitric oxide synthase (eNOS) enzymes synthesize NO from ____ and _____ (in the presence of Ca2+), in endothelial cells.

A

arginine and oxygen

34
Q

____ acts locally in tissues around due to 6 second half life.

A

NO

35
Q

NO diffuses into the vascular smooth muscle cells where it activates _____.

A

soluble guanylate cyclases

36
Q

What are the five actions of NO?

A
  • direct vasodilation
  • indirect vasodilation by inhibiting vasoconstriction
  • anti-thrombotic effect (inhibits platelet activation and vasospasm)
  • anti-inflammatory effect (inhibits leukocyte adhesion to endothelium)
  • anti-proliferative effect (inhibits smooth muscle hyperplasia)
37
Q

What happens when NO reacts with the iron-containing heme groups of oxyhemoglobin in the erythrocytes?

A

NO is rapidly destroyed

38
Q

___ plays a role in the control of blood flow in the heart, blood vessels, brain and muscle.

A

Adenosine

39
Q

How does adenosine regulate cardiac blood flow and function?

A
  • it regulates coronary blood flow (binding to AR2): vasodilation of coronary arterioles
  • it regulates heart rate, contractility (binding to AR1): action through SA and AV nodes
40
Q

____ has a role in vasodilation and capillary leakage of fluids during inflammation.

A

Bradykinin

41
Q

____ causes both powerful arteriolar dilation and increased capillary permeability.

A

Bradykinin

42
Q

____ has a powerful role in vasodilation and leakage of fluids in capillaries and arterioles.

A

Histamine

43
Q

____ is released upon tissue damage, inflammation, or an allergic reaction.

A

Histamine

44
Q

_____ is derived from mast cells in the damaged tissues and from basophils in the blood.

A

Histamine

45
Q

___ is an important vasodilator during hemostasis.

A

Prostacyclin

46
Q

___ is produced by endothelial cells.

A

Prostacycin

47
Q

_____ is a powerful vasoconstrictor, present in endothelial cells, but greatly released upon damage to the endothelium.

A

Endothelin

48
Q

_____ has an important role in hemostasis: helps prevent extensive bleeding from arteries as large as 5 mm in diameter.

A

Endothelin

49
Q

___ has a role in damage to the endothelium by hypertension.

A

Endothelin

50
Q

As little as one millionth of a gram of ___ can increase the arterial pressure of a human being 50 mm Hg or more.

A

Angiotensin II

51
Q

____ normally acts on many of the arterioles of the body at the same time to increase the total peripheral resistance and to decrease sodium and water excretion by the kidneys, thereby increasing the arterial pressure.

A

Angiotensin II

52
Q

_____ is the intrinsic ability of tissue to maintain a relatively constant blood flow despite large fluctuations in blood pressure.

A

Autoregulation

Physiology (15 decks)

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