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Physiology 2nd Bi > Circulation > Flashcards

Circulation Flashcards

1
Q

Systemic capillaries arteriolar ends

A

35mmHg

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2
Q

Sc Venous ends

A

10mmHg

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3
Q

Ave. Capillary pressure

A

17mmHg

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4
Q

Glomerular capillaries pressure

A

60mmHg

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5
Q

T/F

total blood flow through the lungs is the same as that in the systemic circulation because of the lower vascular resistance of the pulmonary blood vessels.

A

True

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6
Q

Ohm’s law in blood vessel

A

F = change in pressure/resistance

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7
Q

the total pulmonary vascular resistance is much higher than the systemic vascular resistance.

T/F

A

False. Lower

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8
Q

Decreased Radius of a Blood Vessel Markedly Increases Vascular Resistance.

A

True

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9
Q

portion slightly away from the wall has moved a small distance, and the portion in the center of the vessel has moved a long distance.

A

para-bolic profile for velocity of blood flow.”

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10
Q

the blood flows crosswise in the vessel and along the vessel, usually forming whorls in the blood, called eddy currents.

A

Turbulent flow

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11
Q

Turbulent flow due to

A

obstruction in a vessel,
when it makes a sharp turn, or
when it passes over a rough surface,

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12
Q

measure of the tendency for turbulence to occur

A

Reynolds’ number

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13
Q

turbulence will usually occur even in a straight, smooth vessel.

A

Reynolds’ number rises above approximately 2000

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14
Q

Pulmonary BP

A

25/8 mmHg

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15
Q

Pulmonary capillary pressure

A

16 mmHg

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16
Q

Thus, the conductance of the vessel increases in proportion to the

A

fourth power of the diameter, in accordance with the following formula:

Conductance = Diameter∝4

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17
Q

blood in the ring touching the wall of the vessel is barely flowing because of its adherence to the vascular endothelium

A

Poiseuille’s Law.

F →(π ∆Pr^4)/(8 η l)

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18
Q

viscosity of normal blood is about 4 times as great as the viscosity of water. T/F

A

False. 3

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19
Q

increase in arterial pressure not only increases the force that pushes blood through the vessels but also

A

initiates compensatory increases in vascular resistance within a few seconds through activation of the local control mechanism

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20
Q

ability of each tissue to adjust its vascular resistance and to maintain normal blood flow during changes in arterial pressure between approximately 70 and 175 mm Hg

A

blood flow autoregulation.

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21
Q

sympathetic  nerve stimulation  or  vasoconstriction  by  hormones  such  as

A

norepineph rine,  angiotensin  II,  vasopressin,  or  endothelin

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22
Q

Vascular distensibility Increase in volume/(Increase in pres × ssure Original volume)

A

fractional increase in volume for each millimeter of mercury rise in pressure

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23
Q

total quantity of blood that can be stored in a given portion of the circulation for each mm Hg pressure rise

A

compliance or capacitance

Vascular compliance=(Increase in volume / Increase in pressure)

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24
Q

the volume of blood injected causes immediate elastic distention of the vein, but then the smooth muscle fibers of the vein begin to “creep” to longer lengths, and their tensions correspondingly decrease.

A

stress-relaxation or Delayed compliance

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25
Q

T he difference between these two pressures, about 40 mm Hg

A

pulse pressure.

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26
Q

diameter of the aortic valve opening is reduced significantly, and the aortic pressure pulse is decreased significantly because of diminished blood flow outward

A

aortic valve stenosis

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27
Q

one half or more of the blood pumped into the aorta by the left ventricle flows immediately backward

allowing the diastolic pressure to fall very low before the next heartbeat.

A

patent ductus arteriosus

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28
Q

after each heartbeat, the blood that has just been pumped into the aorta flows immediately backward

As a result, the aortic pressure can fall all the way to zero between heartbeats

A

aortic regurgitation

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29
Q

there is an incisura in the aortic pulse contour because there is no aortic valve to close.

T/F

A

False. None

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30
Q

velocity of pressure pulse transmission in the aorta

A

3-5 m/sec

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31
Q

velocity of pressure pulse transmission in the large arterial branches,

A

7 to 10 m/sec

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32
Q

velocity of pressure pulse transmission in the small arteries

A

15 to 35 m/sec

33
Q

the greater the compliance of each vascular segment, the slower the velocity, which explains

A

the slow transmission in the aorta and the much faster transmission in the much less compliant small distal arteries

34
Q

cause of damping is twofold:

(1) resistance to blood movement in the vessels, and
2) compliance of the vessels.

Why?

A

resistance damps the pulsations because a small amount of blood must flow forward at the pulse wave front to distend the next segment

compliance damps the pulsations because the more compliant a vessel, the greater the quantity of blood required at the pulse wave

35
Q

primarily responsible for this long-term regulation of arterial pressure; exhibit definitive changes with age, especially after the age of 50 years.

A

kidneys

36
Q

The mean arterial pressure is therefore determined about

A

60 percent by the diastolic pressure and 40 percent by the systolic pressure.

37
Q

pressure in the right atrium is called the

A

central venous pressure

38
Q

factors that can increase this venous return and thereby increase the right atrial pressure are

A

1) increased blood volume
2) increased large vessel tone
3) dilation of the arterioles, which decreases the peripheral resistance

39
Q

normal right atrial pressure

A

0 mm Hg,

40
Q

normal right atrial pressure can increase to 20 to 30 mm Hg under very abnormal conditions, such as

A

1) serious heart failure or (2) after massive transfusion of blood

41
Q

lower limit to the right atrial pressure

A

usually about −3 to −5 mm Hg below atmospheric pressure,

42
Q

thus the pressure in the more peripheral small veins in a person lying down is usually

A

+4 to +6 mm Hg greater than the right atrial pressure.

43
Q

What happens when When the right atrial pressure rises above its normal value of 0 mm Hg,

A

blood begins to back up in the large veins.

44
Q

pressure in the abdominal cavity of a recumbent person normally averages about +6 mm Hg, but it can rise to +15 to +30 mm Hg as a result of

A

pregnancy, large tumors, abdominal obesity, or excessive fluid

45
Q

in an adult who is standing absolutely still, the pressure in the veins of the feet is about

A

+90 mm Hg simply because of the gravitational weight of the blood in the veins between the heart and the feet

46
Q

In the arm veins, the pressure at the level of the top rib is usually about

A

+6 mm Hg

47
Q

+35 mm Hg pressure in the veins of the hand. Y?

A

gravitational difference between the level of the rib and the hand is +29 mm Hg, this gravitational pressure is added to the +6 mm Hg pressure caused by compression of the vein

48
Q

negative pressure can exist in the dural sinuses of the head t/f

A

True

49
Q

if the sagittal sinus is opened during surgery,

A

air can be sucked immediately into the venous system; the air may even pass downward to cause air embolism

50
Q

it is efficient enough that under ordinary circumstances the venous pressure in the feet of a walking adult remains less than +20 mm Hg.

A

venous pump” or “muscle pump,

51
Q

reservoirs and the volume they provide

100 milliliters

several hundred milliliters

as much as 300 milliliters

50 to 100 mil-liliters of blood;

another 100 to 200 milliliters when the pulmonary pressures decrease to low values.

A

spleen, As much as 50 milliliters of concentrated red blood cells can be released into the circulation, raising the hematocrit 1 to 2 percent.

liver, the sinuses of which can release several hundred milliliters of blood into the remainder of the circulation;

the large abdominal veins,

venous plexus beneath the skin, which also can contribute several hundred milliliters.

heart and the lungs, although not parts of the systemic venous reservoir system

52
Q

peripheral circulation of the entire body has about

A

500 to 700 square meters

53
Q

generally have internal diameters of only 10 to 15 micrometers

A

arterioles

54
Q

total thickness of the capillary wall is only about

A

0.5 micrometer

55
Q

The internal diameter of the capillary is — barely large enough for red blood cells and other blood cells to squeeze through.

A

4 to 9 micrometers,

56
Q

most important factor affecting the degree of opening and closing of the metarterioles and precapillary sphincters that has been found thus far

A

is the concentration of oxygen in the tissues.

57
Q

results from thermal motion of the water molecules and dissolved substances in the fluid,

A

Diffusion

58
Q

lipid-insoluble substances that can go only through the pores.

A

sodium ions and glucose
Water
Cl

59
Q

the rate at which water molecules diffuse through the capillary membrane is about 80 times as great as the rate at which plasma itself flows linearly along the capillary

A

True

60
Q

width of the capillary intercellular cleft-pores,

A

Pores. The width of the capillary intercellular cleft-pores, 6 to 7 nanometers, is about 20 times the diameter of the water molecule

61
Q

The capillaries in various tissues have extreme differences in their permeabilities

A

True

62
Q

proportional to the concentration difference of the substance b

A

net” rate of diffusion

concentration of oxygen in capillary blood is normally greater than in the interstitial fluid

63
Q

Determine Fluid Movement Through the Capillary Membrane.

A

Hydrostatic and Colloid Osmotic Forces

64
Q

force f luid outward through the capillary membrane.

tends to cause osmosis of fluid outward through the capillary membrane.

A

capillary pressure

interstitial fluid colloid osmotic pressure

65
Q

force fluid inward through the capillary membrane

cause osmosis of fluid inward through the capillary membrane.

A

interstitial fluid pressure interstitial fluid pressure

capillary plasma colloid osmotic pressure

66
Q

If the sum of the Starling forces is postive, there will be a net fluid absorption from the interstitial spaces into the capillaries.

T/F

A

False. Negative

67
Q

direct micropipette cannulation of the capillaries, which has given an average mean capillary pressure of

A

about 25 mm Hg in some tissues such as the skeletal muscle and the gut,

68
Q

has given a capillary pressure averaging about 17 mm Hg in these tissues.

A

indirect functional measurement of the capillary pressure,

69
Q

the “functional” capillary pressure in this tissue is measured to be about 17 mm Hg.

A

Isogravimetric Method for Indirectly Mea suring “Functional” Capillary Pressure

70
Q

The colloid osmotic pressure of normal human plasma averages about 28 mm Hg

19 mm of this pressure is caused by molecular effects of the dissolved protein and 9 mm is caused by the

A

Donnan effect

71
Q

extra osmotic pressure caused by sodium, potassium, and the other cations held in the plasma by the proteins.

A

Donnan effect

72
Q

the pressures in the arterial and venous capillaries are averaged to calculate mean functional capillary pressure for the entire length of the capillary. This mean functional capillary pressure calcu-lates to be

A

17.3 mm Hg.

73
Q

fluid that must be returned to the circulation through the lymphatics.

A

net filtration,

The normal rate of net filtration in the entire body, not including the kidneys, is only about 2 ml/min

74
Q

whole body capillary filtration coefficient.

A

net filtration rate of 6.67 ml/min of fluid per mm Hg for the entire body

75
Q

any factor that increases interstitial fluid pressure also increases lymph flow

A

Decreased plasma colloid osmotic pressure

Elevated capillary hydrostatic pressure. interstitial fluid colloid osmotic pressure,, permeability of the capillaries

76
Q

any external factor that intermittently compresses the lymph vessel also can cause pumping.

A

Contraction of surrounding skeletal muscles • Movement of the parts of the body • Pulsations of arteries adjacent to the lymphatics • Compression of the tissues by objects outside the body

77
Q

two primary factors that determine lymph flow are

A

the interstitial fluid pressure and (2) the activity of the lymphatic pump

78
Q

When the tissues lose their negative pressure, fluid accumulates in the spaces and the condition known as

A

edema occurs.

Physiology 2nd Bi (5 decks)

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