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HOS Unit 2 > 22 Arteriolar and venous systems > Flashcards

22 Arteriolar and venous systems Flashcards

1
Q

what is the windkessel effect?

A

The Windkessel effect helps in damping the fluctuation in blood pressure (pulse pressure) over the cardiac cycle and assists in the maintenance of organ perfusion during diastole when cardiac ejection ceases. Elastin allows for compliance.

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2
Q

what is the pulse pressure equation?

A

pulse pressure=systolic - diastolic pressure

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3
Q

How do you calculate the MAP?

A

1) MAP= 1/3 systolic + 2/3 diastolic pressures

2) MAP= CO x TPVR (total peripheral vascular resistance)

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4
Q

Is pulse pressure higher in the aorta or in the distal arteries?

A

In the more distal arteries. This is because of their low compliance and wave reflection.

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5
Q

What increases arterial wave pulse velocity?

A

Increased age and vascular disease (arteriosclerosis)

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6
Q

T/F Veins are a lot more compliant than arteries?

A

True, veins are 24 times more compliant. This is why about 67% of the total blood amount is stored in the veins.

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7
Q

What helps to return blood to the heart from venous flow?

A

valves in veins
skeletal muscle contraction
negative intrathoracic pressure during expiration
Increased vascular tone in veins

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8
Q

where is the major site of vascular resistance in the cardiovascular system?

A

in the arterioles. This is why you see such a large drop in pressure on the pressure curve.

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9
Q

what is compliance?

A

how easily a material or tissue can be stretched or distended.

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10
Q

what is the equation for compliance?

A

compliance = V/P (that is delta V over delta P)

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11
Q

__________ is one of the major factors of increased systolic arteriole pressure and pulse pressure?

A

decreased compliance.

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12
Q

T/F Arterial compliance is decreased with high arterial pressures?

A

True, this is because they are already stretched beyond normal.

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13
Q

What is classified as chronic hypertension?

A

multiple BP measurements > 140/90

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14
Q

what is the pulse pressure for 120/80?

A

40 mmHg

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15
Q

How do you take an indirect measurement of the BP? Direct?

A

indirect= sphygmomanometer

direct=arterial cannulation

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16
Q

How does gravity affect blood pressure?

A

Pressure= D x G x H (density, gravity, height)

You should always take the blood pressure at the level of the heart because of the Height factor.

17
Q

what are some things that decrease stroke volume?

A

hemorrhage
aortic stenosis
MI
heart failure

18
Q

what are some things that increase stroke volume?

A

increased blood volume

aortic regurgitation

19
Q

What trend do you usually see with decreased arterial compliance?

A

increased pulse pressure
increased systolic pressure
decreased diastolic pressure

20
Q

T/F Systolic pressure and pulse pressure are both higher in more distal arteries than in the aorta?

A

True
Distal arteries are more stiff (less compliant)
Wave reflection amplifies systolic pressure distally.

21
Q

What is the pulse pressure in the arterioles and capillaries like compared to the distal arteries?

A

pulse pressure is reduced in the arterioles and absent in the capillaries.

22
Q

Where do you find the largest systolic pressures in the circulatory system?

A

In the large arteries such as in the radial artery.

23
Q

T/F Transmission of the pulse wave from the aorta to the distal arteries is slower than the blood flow?

A

False, the pulse wave is much faster.

24
Q

what happens with the speed of the pulse wave with decreased arterial compliance?

A

pulse wave velocity increases. This is important because it can predict cardiac events in patients.

25
Q

What is the law of Laplace?

A

Tension=Pressure x radius

26
Q

T/F The capillary bed is a common place for an aneurism?

A

False. Even though they are very thin walled, they are resistant to bursting. This is because the wall tension (T=P x r) is 12000 times less than in arteries.

27
Q

What is the main function of capillaries?

A

exchange of nutrients (O2, glucose)

exchange of waste products (CO2)

28
Q

What is Fick’s law?

A 
A diffusion equation. J=DA(c1-c2)/T
J=how much material is moved
D=diffusion coefficient
A= area
C= concentration
T=thickness
29
Q

T/F Pinocytosis is commonly found in the capillaries?

A

True. Some larger substances are taken up this way.

30
Q

ACE and NOS are both produced where?

A

Endothelial cells.
1) ACE (angiotensin converting enzyme) angiotensin 1—>2 (vasoconstriction)
2) NOS (nitric oxide synthases)
L-arginine—> NO (vasodilator)

31
Q

What percent of the Cardiac output is filtered through the lymphatics?

A

about 3%

32
Q

What is sterlings law of capillaries?

A

The Starling equation is an equation that illustrates the role of hydrostatic and oncotic forces (the so-called Starling forces) in the movement of fluid across capillary membranes.

Fluid movement= K[(Pc + interstitial oncotic) - (Pi + capillary oncotic)]

K=variable between capillary beds.

33
Q

What is the normal range for capillary hydrostatic pressure pre and post capillary?

A

pre=32mmHg

post=15mmHg

34
Q

What is a normal interstitial hydrostatic pressure value?

A

Close to zero

35
Q

What are some things that cause an increase in capillary hydrostatic pressure? decrease?

A

Increased Pc:
increased arterial pressure, increased venous pressure, increased venous resistance

Decreased Pc:
increased arterial resistance (precapillary)

36
Q

what is one result of an increased capillary hydrostatic pressure and a decreased plasma oncotic pressure?

A

Edema

37
Q

T/F lymphatic vessels have valves?

A

True

38
Q

T/F The venous system is a low pressure, low resistance, and high compliance system?

A

true

39
Q

what do the lymphatics return the circulation?

A

lymph and proteins

HOS Unit 2 (21 decks)

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