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Physiology Exam 2 > L10: Overview of Circulation > Flashcards

L10: Overview of Circulation Flashcards

1
Q

divisions of circulatory system

A

systemic - arteries and veins

pulmonary - heart and lungs

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2
Q

arterial max and minimum pressure at rest

A

120/80

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3
Q

capillary pressures ranges

A

35 to 10

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4
Q

pulmonary systolic and diastolic pressure

A

25

8

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5
Q

phasic pressure

A

present in aorta to capillaries due to ventricle pumping

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6
Q

sharpest pressure decrease

A

present in arterioles due to having the highest resistance

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7
Q

pulse pressure

A

systolic - diastolic
ex.
120 - 80 = 40

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8
Q

arteries in circulation

A

transport under high pressure due to close proximity to ventricle contractions

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9
Q

arterioles are control ___

A

conduits

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10
Q

capillaries are responsible for

A

exchange between blood and extracellular fluid

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11
Q

veins flow rate

A

contain valves to prevent back flow

flow rate is dependent upon current state: contract/dilate
controlled by surrounding muscles

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12
Q

blood distribution broad

A

84% systemic

16% pulmonary

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13
Q

blood distribution to systemic circulation

A 
64% = veins
13% = arteries
7% = capillaries/arterioles
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14
Q

blood flow pattern from heart to lungs

A 
aorta
large to small arteries
arterioles
capillaries
venules
small to large veins
vena cava
pulmonary artery
lungs
arterioles
capillaries
venules
pulmonary vein
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15
Q

velocity of blood flow

A

V = F/A

A = area
F = volume of blood flow
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16
Q

aorta velocity at rest

A

33 cm/sec

A = 2.5

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17
Q

capillaries velocity at rest

A

0.3 cm/sec

A = 2500

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18
Q

aorta diameter

A

2.5

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19
Q

small artery diameter

A

20 total

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20
Q

arterioles diameter

A

40 total

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21
Q

capillary diameter

A

2500 total

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22
Q

venule diameter

A

250 total

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23
Q

small vein diameter

A

80 total

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24
Q

vena cava diameter

A

9

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25
Q

what are the 3 basic principles that underlie circulatory system functions?

A
  1. blood flow to each tissue is controlled by the tissue
  2. the CO is controlled mainly by sum of all the local tissue flows
  3. artery pressure regulation: independent of local blood flow and CO controls
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26
Q

how is blood flow controlled?

A

Microvessels monitor tissue needs
blood flow changes as need changes

they act directly on local vessels causing constriction or dilation

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27
Q

what helps the heart get proper CO needs

A

nerve signals

28
Q

what can activate if arterial pressure falls?

A

nervous reflexes

29
Q

what primarily control cardiac output?

A

the tissues themselves and their dynamic needs

30
Q

nervous reflex in response to arterial pressure below 100 mmHg

A 
reflex will cause:
increased contractile force
constrict large vein reservoirs
constrict arterioles
kidneys may play role
31
Q

2 main factors controlling blood flow rates

A
  1. pressure gradient

2. resistance

32
Q

how do we calculate flow thru a vessel

A

ohm’s law — Poiseuille equation

F = (delta)P/R

33
Q

flow is directly related to_______ . and inversely related to _____ .

A

pressure

resistance

34
Q

Poiseuille’s equation for change in pressure or resistance

A

(delta)P = F*R

R = (delta)P/F

35
Q

adult blood flow at rest

A

5000 mL/min (vessels)
or
5L/min = CO

36
Q

streamline flow

A

laminar flow — flow in layers

37
Q

when does streamline flow occur?

A

flow is a steady rate

vessel is smooth and long/straight

38
Q

in streamline flow where will blood travel the fastest?

A

in the center
or
the farthest distance away from the walls (resistance)

39
Q

nonlayered flow

A

turbulent flow

can create murmurs

40
Q

when does nonlayered flow occur?

A

flow is too great
obstruction w/in vessel
sharp turn
pass over a rough surface

41
Q

a greater resistance in flow, causing a tendency for turbulent flow to increase

A

eddy currents

42
Q

eddy currents are directly related to?

A

velocity of flow
diameter of vessel
density of blood

43
Q

specific gravity of blood

A

1.055

44
Q

eddy currents are inversely related to ?

A

viscosity of blood

blood is 4.5x more viscous than water

45
Q

measure of the tendency for turbulence to occur

A

Reynolds number = Re

Re = (vdp)/n
n = 1/30 …...so
Re = 30vdp
46
Q

what does the n represent in Re equation?

A

viscosity

in blood it always = 1/30poise

47
Q

Re > 200-400

A

turbulent flow will occur somewhere in vessel

48
Q

Re > 2000

A

turbulence will occur in the vessel even if the vessel is straight

49
Q

we can directly measure resistance

A

false, we cannot directly measure it

50
Q

variables used in resistance calculations

A
  1. vessel radius**
  2. blood viscosity
  3. vessel length
51
Q

formulas for resistance

A

R = (delta)P/F

R = 8nl/(pie)r^4

52
Q

what is the most important variable in resistance?

A

vessel radius

53
Q

mean pulmonary arterial pressure

A

16

54
Q

mean left atrial pressure

A

2

55
Q

total pulmonary vascular resistance = ?

A

(pulmonary atrial P - left atria P) / CO

(16-2)/100 = 0.14 PRU

56
Q

PRU

A

peripheral resistance unit

57
Q

resistance of entire systemic circulation = ?

A

total peripheral resistance

58
Q

how to calculate PRU?

A

(CO which = 100mL/sec) / (systemic artery P - systemic vein P)
= resistance of entire systemic circulation

59
Q

R = 4 PRU

A

vessels are strongly constricted

severe blood loss or heart attack

60
Q

R = 0.2 PRU

A

vessels are greatly dilated

61
Q

define conductance

A

measure of blood flow through a vessel for a given pressure difference

62
Q

relate conductance and resistance

A

conductance is the exact reciprocal of resistance

C = 1/R

63
Q

conductance equation

A

Poiseuille’s law
F = (pie)(delta P)r^4 / 8nl

F = flow rate
n = viscosity
l = length
64
Q

relate conductance and diameter

A

conductance is directly proportional to d^4

increase d 4x = flow increase of 256x

65
Q

how does the relationship between conductance and diameter effect blood vessels?

A

a minor change in diameter can have a vast impact on flow rate

Physiology Exam 2 (9 decks)

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