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259 - physiology > lecture 7: chapter 16 > Flashcards

lecture 7: chapter 16 Flashcards

1
Q

what does the term microcirculation refer to

A

functions of the capillaries and the neighbouring lymphatic vessels

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2
Q

what percentage of blood is present in the capillaries at any given time

A

5%

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3
Q

TRUE or false; since there is only 5% of blood in circulation in capillaries it is not important

A

false, it is important for all gaseous exchanges

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4
Q

what is good about having 3-10 billion capillaries

A

there is a larger surface area which allows them to perform the function of solute and fluid exchange
=a lot of places to move places around

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5
Q

what are the 4 functions of the microcirculation

A

Ensures constant plasma and interstitial fluid communication

Accelerates distribution of nutrients, and hormones, and dissolves gases through tissues

Transports insoluble lipids and tissue proteins that cannot cross capillary walls

Flushes bacterial toxins and chemicals to immune system tissues

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6
Q

what is the capillary bed/plexus

A

it connects 1 arteriole to 1 venule

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7
Q

are vascular anastomoses more common in veins or arteries?

A

veins

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8
Q

what do arterial anastomoses provide

A

alternate pathways (collateral channels) for blood to reach a body region

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9
Q

explain how arterial anastomoses provide alternate channels

A

If one branch is blocked, the collateral channel can supply the area with adequate blood supply

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10
Q

what is an example of arteriovenous anastomoses

A

thorough fare channels

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11
Q

where are vascular anastomose common

A

joints, in skin, abdominal organs, brain, heart

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12
Q

what is the trajectory of blood in microcirculation

A

arteriole
meta arteriole
capillaries
venules

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13
Q

what is the composition of arterioles

A

one mono layer or endothelial cells and 1 layer of smooth muscle

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14
Q

what is the composition of meta arteriole

A

one mono layer of endothelial cells with occasional smooth muscle

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15
Q

what is the composition of capillaries

A

1 layer of endothelial with no smooth muscle cells at all

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16
Q

what is the composition of venules

A

1 mono layer of endothelial and some smooth muscle

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17
Q

where is the pre capillary sphincter

A

present at the junction where the capillaries arises from the meta arteriole

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18
Q

what to sphincters respond to

A

local metabolytes

nerological signals

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19
Q

what is the function of the sphincters

A

regulate flow direction into true capillaries or through channels

guard the entrance to each capillary

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20
Q

what allows blood flow to be changed by sphincters

A

vasomotion-contraction and relation cycle of capillary sphincters

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21
Q

what causes the blood flow in capillary beds to constantly change routes

A

sphincters

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22
Q

what is blood flow regulated by and what does that mean

A

regulated by vasomotor nerves and local chemical condition, so it can either bypass or blood the capillaries

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23
Q

true or false: blood always floods and flows through the enter capillary bed

A

no, it can be redirected dependant on tissue needs

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24
Q

what are the 3 types of capillaries

A

continuous
fenestrated
sinusoidal

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25
Q

where are continuous capillaries usually found

A

in skin and muscles

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26
Q

true or false: continuous capillaries are not efficient at moving substances in and out because the endothelial cells are so close together

A

true

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27
Q

what is characteristic of endothelial cells in continuous capillaries

A

the endothelial cells are so close so they provide an uninterrupted lining

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28
Q

what are adjacent cells held together with

A

tight junctions

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29
Q

what allows the passage of fluids in continuous capillaries

A

intercellular clefts

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30
Q

where is an example of continuous capillaries of the brain and why its used there

A

in the brain
there are tight junctions completely around the endothelium

constitute the blood-brain barrier to make a protective against toxins

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31
Q

where are fenestrated capillaries found

A

where there is active capillary absorptions or filtrate formation occurs

(ex: small intestine, endocrine glands, kidneys

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32
Q

explain the endothelium in fenestrate capillaries

A

riddled with pores (fenestrations)

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33
Q

which type of capillaries have the greatest permeability to solutes and fluids

A

fenestrate capillaires

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34
Q

true or false: since fenestrated capillaries have pores they don’t have intercellular clefts

A

false, they do have

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35
Q

what are sinusoid (discontinuous) capillaries

A

highly modified, leaky, fenestrated capillaries with large lumens

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36
Q

where are sinusoid (discontinuous) capillaries

A

found in the liver, bone marrow, lymphoid tissue and some endocrine organs

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37
Q

which capillaries have the biggest pores

A

discontinuous

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38
Q

what is the function of discontinuous capillaries

A

allow large molecules (proteins and blood cells) to pass between the blood and surrounding tissues

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39
Q

true or false: has blood passes from continuous to discontinuous is becomes more sluggish/less laminar

A

true

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40
Q

what are capillaries composed of

A

unicellular layer of endothelial cells surrounded by basement membrane

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41
Q

how does solute and water move across capillary wall

A

intercellular cleft (space between cells) or by plasmalemma vesicles.

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42
Q

what is the diameter of capillaries

A

4-9 microns

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43
Q

what is the main passage of substances through capillary to tissue

A

through clefts

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44
Q

what are the smallest blood vessels

A

capillaries (allow only 1 single RBC to pass at a time)

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45
Q

what is the width of capillary intercellular slit pores?

A

6-7 nanometers

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46
Q

what does the The permeability of the capillary pores for different substances varies according to

A

their molecular diameters.

47
Q

true or false and why: The capillaries in different tissues have no differences in their permeabilities

A

The capillaries in different tissues have extreme differences in their permeabilities
because of fenestrations

48
Q

give an example of how different tissues have different permeability

A

liver takes large molecules so their capillaries will have a higher fenestration

49
Q

how do water, ions, and small molecules (glucose) get diffuse

A

diffuse between adjacent endothelial cells

or through fenestrated capillaries

50
Q

how do some ions like NA+, K+ ca2+ and Cl- diffuse through

A

though channels in cell membranes

51
Q

how do large, water soluble compounds pass through/diffuse

A

pass through fenestrated capillaries (and occasionally through endothelial cells)

52
Q

how do lipids and lipid soluble materials (o2 and co2) diffuse through

A

through endothelial cell membranes

53
Q

how to plasma proteins diffuse through

A

cross endothelial lining in sinusoids (really large pores)

54
Q

the larger the side the harder/easier to permeate

A

harder to permeate

55
Q

true or false: since hemoglobin and albumin have the same molecular weight, they have the same permeability

A

false, albumin has a harder time permeating

56
Q

why is albumin harder to permeate than hemoglobin?

A

Gibbs Donnan effect

albumin have a greater osmotic force

57
Q

explain why albumin has a greater osmotic force

A

albumin has a negative charge (attracts sodium ions)

albumin binds a small number of chloride ions (attracts more sodium ions)

58
Q

explain why albumin has a hard time permeating

A

because of its greater osmotic force is pulls liquid towards it

59
Q

Most important means by which substances are transferred between plasma and interstitial fluid is by what

A

diffusion

60
Q

since salt has a high osmotic force what does that do for diffusion

A

it attracts fluid in the capillary (pulls water out)

61
Q

what is the space between cells called

A

interstitium

62
Q

what is the fluid in the interstitium called

A

interstitial fluid

63
Q

what is the consistency of interstitial fluid

A

gel

64
Q

what are the two major types of solid structures in the interstitium called

A

collagen fibers and proteoglycan filaments (coiled molecules composed of hyaluronic acid)

65
Q

true or false: there is very little free fluid under normal conditions in interstitium

A

true

66
Q

the collagen bundle fibers in the interstitium provide what

A

structure

67
Q

explain the capillary exchange at the arterial end of the capillary

A

fluid moves OUT of the capillary

into the itnersticial fluid

68
Q

explain capillary exchange at the venous end of capillary

A

fluid moves INTO capilary

OUT OF THE INTERSTICUAL FLUID

69
Q

what are the 2 hydrostatic forces

A

capillary hydrostatic pressure

interstitial fluid hydrostatic pressure

70
Q

where is capillary hydrostatic pressure higher and why

A

higher at the arteriolar end than venule

*because of ressitance)

71
Q

where does capillary hydrostatic pressure force fluid

A

forces fluid outward through the capillary membrane

pushes fluid from cap to interstitium

72
Q

Normally interstitial fluid hydrostatic pressure is negative or positive

A

negative

73
Q

what is the negative pressure in the interstitual fluid hydrostrate pressure caused by

A

pumping action of lymphatics

the fluid is constantly drained and leaking out of interstitium which helps push more fluid in

74
Q

where does interstitial fluid hydrostatic pressure force fluid

A

usually pushes fluid from cap to interstitium (except for when pressure is positive)

75
Q

when interstitial fluid pressure is positive what happens

A

it opposes filtration

76
Q

capillary hydrostatic pressure is good for absorption or filtration

A

filtration

77
Q

interstitial fluid hydrostatic pressure is good for filtration or absorption

A

reabsorption (when pos)

78
Q

what are the osmotic forces

A

plasma colloid osmotic pressure

interstitial fluid osmotic pressure

79
Q

what is another name for plasma colloid osmotic pressure

A

plasma oncotic pressure

80
Q

what is the major determinants of oncotic pressure

A

plasma proteins

81
Q

what is the most abundant plasma protein and what does it generate

A

albumin, generates 70% of oncotic pressure

82
Q

plasma colloid osmotic pressure/plasma oncotic pressure tends to cause what

A

IN AWARD (INTO CAPILLARY) MOVEMENT OF FLUID

83
Q

WHAT IS another name for interstitial fluid osmotic pressure

A

interstitial fluid oncotic pressure

84
Q

what is interstitial fluid osmotic pressure caused by

A

small amount of plasma proteins that leak into the interstitial space

85
Q

interstitial fluid osmotic pressure tends to cause inward or outward movement of fluid

A

outward movement

86
Q

plasma colloid osmotic pressure opposes what and what does that cause

A

opposes filtration, causing osmosis of water inward through the membrane

87
Q

interstitial fluid colloid pressure promotes what and why

A

promotes filtration by causing osmosis of fluid outward through membrane

88
Q

what is filtration

A

The sum of the hydrostatic and osmotic forces favours the net movement of water from the capillary to the interstitial space

89
Q

what is reabsorption

A

The sum of the hydrostatic and osmotic forces favors the net movement of water from the interstitial space to the capillary

90
Q

what is the filtration rate

A

the net filtration pressure (NFP) multiplied by the coefficent filtration

91
Q

what is the NNFP format

A

NFP= PC - Pic - Pip + Piif

92
Q

what is the filtration coefficent

A

Kf

product of surfeace area times the hydraulic conductiveity of memberan

93
Q

know the determinants of net fluid movement across capillaries

A

diagram of capillary and 4 pressures

94
Q

what is the starling equilibrium

A

The Starling equation describes the net flow of fluid across a semipermeable membrane. It describes the balance between capillary pressure, interstitial pressure, and osmotic pressure.

95
Q

what is the normal capillary hydrostatic pressure

A

approx 17 mmHg

96
Q

what is the normal interstitial fluid pressure in most tissues

A

-3

97
Q

what type of organs have positive interstitial pressures

A

encapsulated organs

98
Q

what is the negative interstitial fluid pressure caused by

A

pumping of lymphatic system

99
Q

what is colloid osmotic pressure caused by

A

large proteins

100
Q

what increases the colloid osmotic effect of proteins

A

presence of negative ions on proteins (Gibbs Donnan)

101
Q

what is the reflection coefficient of capillaries

A

it quantitates the amount of protein that is reflected away from capillary membrane

102
Q

what does a reflection coefficient of 1 mean

A

all proteins are reflected and none pass through pores

103
Q

what does a reflection coefficient of 0 mean

A

it is permeable to all proteins

104
Q

true or false: physiologically you can never have a coefficient of 1 or 0

A

true

105
Q

go over the 3 slides about forces causing filtration, reabsorption etc

A
106
Q

what is the net filtration pressure and what does that cause

A

0.3 mmHG which causes a net filtration rate of 2 ml/min for the entire body
(this means we are constantly moving more fluid from capillary to interstitium than opposite)

107
Q

even though there is a net outward force (moving fluid from cap to interstitium) do the vessels swell

A

no because of the draining from lymphatic systems

108
Q

where is the transition point

A

it is a point between filtration and reabsorption where there is equilibrium

109
Q

is the transition point closer to venous end or arterial end

A

closer to venous

110
Q

true or false: capillaries filter more than they reabsorb

A

true

111
Q

is the transition point always the same? give example

A

no it changes depending on the needs of the tissue (whether they need more filtration or reabsorption)

ex: in skeletal we need a lot of filtration so it will, be closed to venous side

112
Q

during filtration, are we only moving fluid?

A

no also moving oxygen, glucose etc

113
Q

during reabsorption are we only moving fluid?

A

no also waste products

259 - physiology (21 decks)

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