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HF&F > Capillary Permeability (9/9) w/Smith > Flashcards

Capillary Permeability (9/9) w/Smith Flashcards

1
Q

T/F: The more metabolically active a cell or environment is, the more capillaries are required to supply nutrients and carry away waste products.

A

True.

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2
Q

How much blood is in the capillaries at any given time? Why is this blood so important?

A
  • only ~5% of circulating blood is in the capillaries at any given time, but this 5% is the more important part of blood volume.
  • Only blood from which nutrients can enter the interstitial fluid and into which CO2 and waste products can enter the bloodstream.
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3
Q

What type of cells are the capillary wall made up of? Why?

A

a single layer of endothelial cells to promote efficient exchange.

The cell wall is so thin that RBCs can only pass through in single file.

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4
Q

Do capillaries have a smooth muscle layer?

A

No.

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5
Q

Capillaries are also involved in the body’s release of excess ____?

A

Heat. This is why your skin looks flushed after exercise.

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6
Q

Virtually all nutrients, gases, metabolites and water are continuously exchanged between the blood and cells via what?

A

Capillary exchange.

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7
Q

What type of cells serve as the semipermeable membrane between the external interstitial fluid and the plasma inside the capillary?

A

Endothelial cells

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8
Q

Capillaries are efficient sites for gas and nutrient exchange because:

A
  • blood velocity is low

- HUGE surface area

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9
Q

What is diffusion:

A

The movement of a solute from an area of high concentration to an area of low concentration.

Regarding capillaries it is the movement of nutrients, O2, CO2, and lipid soluble substances through the semipermeable capillary wall.

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10
Q

T/F: Plasma proteins generally can cross the capillary wall.

A

FALSE. Plasma proteins generally CANNOT cross the capillary wall.

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11
Q

What is bulk flow (ultrafiltration)?

A

movement of protein-free ECF and water-soluble substances in & out though water-filled pores or intercellular clefts.

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12
Q

What is vesicular transport?

A

translocation of larger, exchangeable macromolecules (insulin, IgA) across the endotelium via trancytosis.

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13
Q

What are the 4 routes of transport across the capillary wall?

A
  • Diffusion
  • Intercellular capillary clefts
  • Fenestrations or pores
  • Transcytotic or Pinocytotic vesicles
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14
Q

What molecules are easily diffused across the membrane?

A

lipid-soluble molecules

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15
Q

What substances are transported through intercellular capillary clefts?

A

water-soluble substances

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16
Q

What substances are transported through fenestrations or pores?

A

water-soluble substances

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17
Q

What molecules are or substances are transported via transcytoic or pinocytoic vesicles?

A

Large substances such as insulin, IgA, etc.

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18
Q

T/F: At equilibrium, the net movement of solute stops.

A

True. Although random (Brownian) motion continues.

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19
Q

The difference in concentration between the area of high versus low concentration is called what?

A

The concentration gradient.

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20
Q

T/F: Diffusion requires energy.

A

FALSE. Diffusion does NOT require energy; it is driven by osmotic gradients.

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21
Q

What 4 factors can affect the rate of diffusion?

A
  • temperature
  • concentration gradients
  • size of solute
  • viscosity of solution
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22
Q

T/F: diffusion is faster at a higher temperature.

A

True.

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23
Q

T/F: diffusion is slower with a higher concentration gradient.

A

FALSE. Diffusion is faster when solute is moving from an area of high concentration to low concentration.

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24
Q

T/F: diffusion is faster for larger solutes.

A

FALSE. Diffusion is slower for large molecules, and fast for small molecules.

*Large molecules may be unable to diffuse at all and may require transport.

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25
Q

T/F: Diffusion is slower in more viscous solutions.

A

True.

26
Q

T/F: Diffusion can only occur if the membrane is permeable to the solute.

A

True.

27
Q

What is Brownian motion?

A

(aka pedesis) is the random motion of particles suspended in a fluid resulting from their collision with the atoms or molecules in the gas or liquid.

28
Q

T/F: lipid-soluble materials cannot pass directly through the plasma membrane or endothelial cells.

A

FALSE. Lipid-soluble materials (O2, CO2, & steroid hormones) can pass directly through the plasma membrane.

29
Q

T/F: Water-soluble materials must pass through fenestrations or spaces between endothelial cells.

A

True. Water-soluble materials (glucose, ions, amino acids) pass between endothelial cells via bulk flow or vesicular transport.

*They are not diffused.

30
Q

What is a colloid?

A

A mixture in which very small particles of one substance are distributed evenly throughout another substance. The particles will not settle.

31
Q

What are the 6 main classes of blood vessels?

A
  • arteries
  • arterioles
  • capillaries
  • venules
  • veins
  • anastomoses
32
Q

What does an artery do?

A

carries blood away from the heart; branches decrease in diameter.

33
Q

What do aterioles do?

A

connect to capillaries

34
Q

What are capillaries?

A

tiny vessels where diffusion occurs between blood and interstitial fluid.

35
Q

What are venules?

A

smallest veins; connect to other capillaries

36
Q

What do veins do?

A

Return blood to heart; converge and increase in diameter.

37
Q

What do anastomoses do?

A

bypass connections between vessels.

38
Q

Where in the capillary bed is the plasma fluid filtered out?

A

the arteriolar end.

39
Q

Where in the capillary bed is the plasma fluid reabsorbed?

A

at the venous end.

40
Q

What happens to the fluid that remains int he interstitial space?

A

it becomes part of the interstitial fluid compartment.

41
Q

T/F: Lymphatic vessels collect excess interstitial fluid and return it to the venous bloodstream.

A

True. Once collected in the lymphatic vessels, it is called lymph.

42
Q

T/F: Lymphatic vessels form a one-way system in which lymph only flows back toward the heart.

A

True.

43
Q

What are the 3 Starling Forces?

A
  • Crystalline osmotic pressure
  • Oncotic pressure (colloid osmotic pressure)
  • Hydostatic pressure
44
Q

What is crystalline osmotic pressure?

A

oncotic pressure due to small molecules in the plasma (Na, Cl, sodium bicarbonate, glucose, urea, amino acids, etc.)

45
Q

Do the water soluble molecules involved with crystalline osmotic pressure (mentioned on the last flash card) have an effect on water flow?

A

No. Because they are water-soluble, their concentrations are equivalent on either side of the capillary wall, so there is no effect on water flow.

46
Q

Oncotic pressure

A

(aka colloid osmotic pressure) is the osmotic pressure exerted by impermeable plasma proteins, notably alubumin, that pull water into the circulatory system from the interstitial fluid.

*know = it pulls water into the capillary.

47
Q

Where does oncotic pressure increase?

A

along the length of the capillary, particularly in capillaries with high filtration, due to filtering fluid leaving behind an increased concentration of proteins

48
Q

What is hydrostatic pressure?

A

force that is directed out of the capillary by a fluid pushing against the capillary wall.

49
Q

Describe Starling’s Law:

A

Fluid leaves (via filtration) or re-enters (via reabsorbtion) the capillary depending on how the opposing pressures in the capillary and in the interstitial space relate to one another (Hydrostatic and oncotic)

50
Q

How do the pressures drive fluid flow across the capillary?

A

hydrostatic pressure in the capillary “pushes” fluid out.

Osmotic pressure in the capillary “pulls” fluid in.

51
Q

Where is velocity of blood flow the fastest?

A

in the aorta

52
Q

Where is velocity of blood flow the slowest?

A

in capillaries

53
Q

T/F: The pressure gradient provides the driving force that keeps blood moving from higher to lower pressure areas.

A

True.

54
Q

Where is the largest drop in pressure in the vessels?

A

arterioles.

55
Q

T/F: Slow velocity of blood flow through the capillaries facilitates exchange time.

A

True.

56
Q

Capillary beds:

A

branch off the metarteriole and return to the thoroughfare channel at the distal end of the bed; **site of optimal exchange.

57
Q

vascular shunts:

A
  • metarteriole
  • thoroughfare channel

Both connect an arteriole directly with a postcapillary venule, (bypassing the true capillary bed).

58
Q

Precapillary sphincter:

A

cuff of smooth muscle that surrounds each true capillary.

regulated blood flow.

59
Q

vasomotion

A

the slow, intermittent flow of blood through the capillaries

60
Q

Lympatic capillaries

A

blind-ended sacs in interstitial space

  • low pressure
  • absorb fluids from interstitial space
  • unidirectional
  • wider than blood capilaries
  • colorless
61
Q

Blood capillaries

A
  • join to arterioles on one end and venules on the other end
  • higher pressure than lymphatic capillaries
  • filter then reabsorb most fluids by bulk flow
  • narrower than lymph capillaries
  • reddish
62
Q

What are 4 potential causes of edema?

A
  • increased capillary blood pressure
  • decreased plasma colloid osmotic pressure
  • increased capillary permeability
  • Obstruction/disruption of lymphatic

HF&F (13 decks)

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