Capillary Permeability Flashcards

1
Q

capillary wall is composed of a

A

single layer of endothelial cells

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2
Q

what are two reasons for the efficient exchange of gases/nutrients in capillaries?

A
  1. Blood velocity is very slow: “sluggish” gives adequate time for exchange across the capillary membrane
  2. Huge surface area: over 10 million capillaries
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3
Q

Capillary permeability:
fastest blood velocity?
slowest blood velocity?

A

fastest: aorta
slowest: capillaries

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4
Q

Capillary permeability:

velocity is ______ proportional to the ______ ____

A

velocity is inversely proportional to cumulative area

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5
Q

velocity of blood flow =

A

V = F/A

V=velocity
F=flow rate
A=cross-sectional area of vessels

*velocity is inversely proportional to the cumulative area

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6
Q

hydrostatic pressure:

A

the force per unit area exerted on the wall of a blood vessel by the blood moving through it

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7
Q

slower flow promotes _______ & _______

A

greater gas and nutrient exchange

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8
Q

low pressure protects capillaries from ________

A

rupture

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9
Q

normal capillary BP is ______

A

low

*protects capillaries from rupture and promotes exchange

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10
Q

BP ______ as blood flow leaves the capillaries

A

lowers

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11
Q

hydrostatic pressure ____ as you move from the aorta to arteries then to arterioles, and so on…

A

decreases

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12
Q

at any time on ____% of circulating blood is in the capillaries

A

~5%

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13
Q

what percent of blood is considered the most important portion of blood volume and where is it located?

A

~5% in capillaries

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14
Q

where does O2 enter from capillaries?

A

interstitial fluid (IF)

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15
Q

where do CO2 and waste products enter from the tissues?

A

capillaries/bloodstream

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16
Q

virtually all gases, nutrients, metabolites, and water are continuously exchanged via…

A

capillary exchange

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17
Q

what is exchanged in “capillary exchange”?

A

gases
nutrients
metabolites
water

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18
Q

what is between the external interstitial fluid and plasma inside the capillary?

A

endothelial cells
*single layer
*semipermeable

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19
Q

T/F: capillaries have smooth muscle in their walls

A

FALSE

capillaries do NOT have smooth muscle in their walls

controlled by the large arterioles

*constricting their capillary sphincters

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20
Q

how do capillaries help in temperature regulation?

A

cool down via heat loss: vasodilation (increases blood flow)

warm-up via prevent heat loss: vasoconstriction (decreases blood flow)

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21
Q

how do capillaries respond to hot weather?

A

HEAT LOSS

vasodilation (increased blood flow)

cools down body

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22
Q

how do capillaries respond to cold weather?

A

PREVENT HEAT LOSS

vasoconstriction (decreased blood flow)

warms body up (bluish hands/feet)

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23
Q

if the precapillary sphincter is closed what happens?

A

precapillary sphincter closed =

blood flows only through the metarteriole and thoroughfare channel (center of the capillary)

not branching out to capillary bed

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24
Q

if the precapillary sphincter is open what happens?

A

precapillary sphincter open =

blood flows through capillary beds

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25
Q

study

A
26
Q

how are exchangeable proteins moved across the capillary membrane?

A

vesicular transport

27
Q

how are small water-soluble substances moved across the capillary membrane?

A

through intercellular clefts (bulk flow)

28
Q

how are lipid-soluble substances moved across the capillary membrane?

A

diffusion through endothelial cells (semipermeable membrane)

*concentration gradient

O2, CO2

29
Q

what are lipid-soluble substances of capillary permeability?

A

O2
CO2

30
Q

three modes of transport for substances to pass through capillaries?

A
  1. Diffusion - no energy required (O2, CO2)
  2. Intercellular cleft (water-soluble)
  3. Vesicular transport (large proteins)
31
Q

What are some factors that affect the rate of diffusion in capillaries?

A

high temperatures (faster)
low temperatures (slower)

higher concentration gradient (faster)
lower concentration gradient (slower)

small solutes (faster)
large solutes (slower)

viscous solutions (slower)

32
Q

What is the term for endocytosis to exocytosis in capillary permeability?

A

vesicular transcytosis

33
Q

vesicular transport is the translocation of _____ macromolecules in vesicles

A

impermeable (like large solutes, proteins, antibodies)

*requires energy ATP

34
Q

what is “bulk flow “of capillary transport?

A

how smaller water-soluble solutes move across the capillary wall

35
Q

what capillary types affect bulk flow? ranked

A

continuous capillaries: least flow

fenestrated capillaries: more flow

discontinuous capillaries: most flow

36
Q

Starling Forces of capillary Bulk Flow

A

Filtration: bulk flow of solutes move from bloodstream to interstitial fluid

Reabsorption: bulk flow of solutes from interstitial fluid to bloodstream

37
Q

what forces impact Filtration (Starling Forces of capillaries)?

A

capillary hydrostatic pressure
interstitial fluid osmotic pressure

*blood stream to interstitial fluid

38
Q

what forces impact Reabsortion (Starling Forces of capillaries)?

A

capillary oncotic pressure “colloid osmotic pressure”
interstitial fluid hydrostatic pressure

*bloodstream to interstitial fluid

39
Q

Starling’s Law equation in words

A
40
Q

Starling’s Law equation

A

NFP= net filtration pressure

HPc= capillary hydrostatic pressure

HPif= interstitial fluid hydrostatic pressure

OPc= capillary oncotic pressure

OPif= interstitial fluid osmotic pressure

41
Q

Capillary Ontotic Pressure aka Colloid osmotic pressure: osmotic pressure exerted primarily by _______

A

impermeable plasma proteins

42
Q

capillary hydrostatic pressure is …

A

the froce directed out of the capillary by fluid pushing against the capillary

43
Q

hydrostatic pressure in capillaries moves fluid ____ of capillary

A

out

44
Q

osmotic pressure in capillaries moves fluid ____ capillary

A

into

45
Q

hydrostatic pressure in interstitial fluid moves fluid ____ capillaries

A

into

46
Q

osmotic pressure in interstitial fluid moves fluid ____ of capillaries

A

out

47
Q

Where are plasma fluids filtered out of a capillary?

Whare are plasma fluids reabsorbed in a capillary?

A

filtered out: capillary’s arteriolar end (~20L/day)

reabsorbed: venous end (~17L/day)

48
Q

the fluid that remains in the interstitial space becomes part of the interstitial fluid and is then removed by the _____

A

lymphatic system (~3L/day)

49
Q

what goes through the three modes of transport of capillary exchange?

A
  1. diffusion: lipid-soluble O2/CO2
  2. Vesicular transport: large proteins insulin/IgA
  3. Bulk Flow (convection): water-soluble, plasma/IF/electrolytes/ions/glucose/amino acids
50
Q

trace of the capillary system from arteries to veins

A

arteries
arterioles
capillaries
venules
veins

51
Q

what are anastomoses?

A

a point where two blood vessels merge

can serve as a bypass connection between vessels

*no capillary beds

52
Q

the primary function of the lymphatic system

A

lymphatic system: move fluid/lymph directionally towards the heart (one way)

return excess lymph fluid to heart and helps large molecules (hormones/lipids) enter the blood

53
Q

lymphatic capillaries have relatively _______

A

low pressure

54
Q

blood capillaries vs lymphatic capillaries

A

blood:
high pressure
narrow
reddish

lymphatic:
low pressure
wide
colorless

55
Q

potential causes of edema

A
  1. increased capillary blood pressure
  2. decreases plasma colloid osmotic (oncotic) pressure
  3. increased capillary permeability
  4. obstruction/disruption of lymphatics (lymphedema)
56
Q

edema: increased capillary blood pressure is due to…

A

increased plasma volume
increased venous pressure
arteriolar dilation

57
Q

edema: decreased plasma colloid osmotic (oncotic) pressure is due to…

A

decrease plasma albumin/large plasma proteins

58
Q

edema: increased capillary permeability is due to…

A

filtration of proteins into interstitial space
increase in interstitial oncotic pressure

*increased interstitial fluid exceeds the lymphatic systems compensatory return

59
Q

lymphedema?

A

swelling of body parts (distal limbs)

unable to return access fluids to the venous blood supply

buildup of fluids in lymphatics and interstitial tissue

60
Q

lymphostatic fibrosis?

A

process of built-up fluid in limbs hardens (permanent scarring)

61
Q
A