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Zak, Physiology > Lecture 9: Circulation > Flashcards

Lecture 9: Circulation Flashcards

0
Q

What is systolic pulmonary artery pressure?

A

25 mmHg

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1
Q

What does systemic capillary pressure range from?

A

35 mmHg-10 mmHg

35 mmHg when entering from arterioles

10 mmHg when leaving through venules

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2
Q

What is pulmonary diastolic pressure?

A

8 mmHg

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3
Q

What percentage of blood volume is in systemic circulation?

A

84%

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4
Q

What percentage of blood volume is in the veins?

A

64%

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5
Q

What percentage of blood volume is in the arteries?

A

13%

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6
Q

What percentage of blood volume is in the arterioles and capillaries?

A

7%

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7
Q

What percentage of blood volume is in the heart and lungs?

A

16%

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8
Q

What does it mean to say “the velocity of blood flow is INVERSELY proportional to vascular cross-sectional area”?

A

If cross-sectional area increases, velocity decreases

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9
Q

T/F: V=F/A means if F increases, V increases

A

True

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10
Q

What are the 3 basic principles underlying all functions of the circulatory system?

A

1) Rate of blood flow to each tissue is precisely controlled in relation to tissue need
2) Cardiac output is controlled by the sum of all local tissue flows (heart will pump out what tissues need)
3) Arterial pressure regulation is independent of local blood flow control or cardiac output control

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11
Q

What does functional principle 1 of circulatory system mean?

A

Microvessels control tissue needs by acting on local blood vessels and dilating/constricting them

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12
Q

What does functional principle 2 of circulatory system mean?

A

Heart responds to demands of tissue

Nerve signals may be needed to help heart pump required amount of blood

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13
Q

What does functional principle 3 of circulatory system mean?

A

If arterial pressure drops below 100 mmHg, nervous reflexes…

Increase force of heart pumping

Constrict large venous reservoirs

Constrict most arterials throughout body

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14
Q

What is flow proportional to?

A

Directly proportional to pressure difference

Inversely proportional to resistance

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15
Q

What is the overall blood flow of an adult at rest?

A

5,000 ml/min

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16
Q

What is laminar flow?

A

Layered blood flow that flows in a steady state

17
Q

T/F: Laminar blood flow equals streamline flow

A

True

18
Q

T/F: Velocity of blood flowing near vessel walls flows quicker than blood flowing near center of vessel

A

False, blood flowing in center of vessel flows quicker than blood flowing near vessel walls

19
Q

When does turbulent flow occur?

A

When…

Flow is too great

Blood passes obstruction

Blood makes sharp turn

Blood passes rough surface

20
Q

What is another term for turbulent flow?

A

Eddy current

21
Q

What is Reynolds Number (Re) a measure of?

A

Tendency for turbulence to occur

22
Q

What is Reynolds Number directly proportional to?

A

Velocity

Vessel diameter

Density

23
Q

What is Reynolds Number indirectly proportional to?

A

Viscosity

24
Q

At what Re number will turbulent flow occur in some regions?

A

When Re is above 200-400

25
Q

At what Re number will turbulent flow occur in straight vessels?

A

When Re is above 2,000

26
Q

What is the definition of blood pressure?

A

Force exerted by blood against any unit area of the vessel wall

27
Q

What is the definition of resistance?

A

Impediment to blood flow

28
Q

How do you calculate systemic resistance?

A

Cardiac output/Pressure difference from systemic arteries to systemic veins= _____PRU

CO=100 ml/sec

P=100 mmHg

Resistance=100/100=1PRU

29
Q

When vessels are highly constricted, PRU may rise to what?

A

4 PRU

30
Q

When vessels are dilated, PRU may fall to what?

A

PRU 0.2

31
Q

How do you calculate resistance in pulmonary system?

A

(Pulmonary arterial pressure-Left atrial pressure)/Cardiac output=_____PRU

*Cardiac output does not ∆ b/w pulmonary & systemic circulation

AP=16 mmHg

LP=2 mmHg

CO=100 ml/sec

Resistance=14/100=0.14PRU

32
Q

What is the definition of conductance?

A

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

It is the exact reciprocal of resistance (1/resistance)

33
Q

T/F: Blood vessels arranged in series have a total resistance much less than the resistance of any single blood vessel.

A

False, blood vessels arranged in PARALLEL have a total resistance much less than the resistance of any single blood vessel

34
Q

Does amputation or removal or an organ increase or decrease total peripheral resistance?

A

Increase

35
Q

How much higher is blood viscosity than water, and why is that the case?

A

3x higher because of the RBC’s

36
Q

What is polycythemia?

A

Having a hematocrit around 60-70

37
Q

What is anemia?

A

Having a hematocrit around 10

38
Q

If there are more RBC’s in the blood, the viscosity will be _______.

A

Greater

39
Q

What is autoregulation?

A

Ability for tissues to adjust vascular resistance through changes in arterial pressure between 700-175 mmHg

40
Q

What happens when autoregulation drops below 75?

A

It becomes very tough to keep blood flow going

41
Q

What happens when autoregulation gets below 50?

A

Blood flow ceases

Zak, Physiology (20 decks)

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