22 Arteriolar and venous systems

Question 1

what is the windkessel effect?

Answer 1

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.

Question 2

what is the pulse pressure equation?

Answer 2

pulse pressure=systolic - diastolic pressure

Question 3

How do you calculate the MAP?

Answer 3

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

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

Question 4

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

Answer 4

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

Question 5

What increases arterial wave pulse velocity?

Answer 5

Increased age and vascular disease (arteriosclerosis)

Question 6

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

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

what is compliance?

Answer 9

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

Question 10

what is the equation for compliance?

Answer 10

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

Question 11

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

Answer 11

decreased compliance.

Question 12

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

Answer 12

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

Question 13

What is classified as chronic hypertension?

Answer 13

multiple BP measurements > 140/90

Question 14

what is the pulse pressure for 120/80?

Answer 14

40 mmHg

Question 15

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

Answer 15

indirect= sphygmomanometer

direct=arterial cannulation

Question 16

How does gravity affect blood pressure?

Answer 16

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.

Question 17

what are some things that decrease stroke volume?

Answer 17

hemorrhage
aortic stenosis
MI
heart failure

Question 18

what are some things that increase stroke volume?

Answer 18

increased blood volume

aortic regurgitation

Question 19

What trend do you usually see with decreased arterial compliance?

Answer 19

increased pulse pressure
increased systolic pressure
decreased diastolic pressure

Question 20

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

Answer 20

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

Question 21

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

Answer 21

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

Question 22

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

Answer 22

In the large arteries such as in the radial artery.

Question 23

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

Answer 23

False, the pulse wave is much faster.

Question 24

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

Answer 24

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

Question 25

What is the law of Laplace?

Answer 25

Tension=Pressure x radius

Question 26

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

Answer 26

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.

Question 27

What is the main function of capillaries?

Answer 27

exchange of nutrients (O2, glucose) | exchange of waste products (CO2)

Question 28

What is Fick's law?

Answer 28

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

Question 29

T/F Pinocytosis is commonly found in the capillaries?

Answer 29

True. Some larger substances are taken up this way.

Question 30

ACE and NOS are both produced where?

Answer 30

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

Question 31

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

Answer 31

about 3%

Question 32

What is sterlings law of capillaries?

Answer 32

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.

Question 33

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

Answer 33

pre=32mmHg | post=15mmHg

Question 34

What is a normal interstitial hydrostatic pressure value?

Answer 34

Close to zero

Question 35

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

Answer 35

Increased Pc: increased arterial pressure, increased venous pressure, increased venous resistance Decreased Pc: increased arterial resistance (precapillary)

Question 36

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

Answer 36

Edema

Question 37

T/F lymphatic vessels have valves?

Answer 37

True

Question 38

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

Answer 38

true

Question 39

what do the lymphatics return the circulation?

Answer 39

lymph and proteins