Biomechanical Properties of Blood Vessels

Question 1

What are the 3 layers of a blood vessel wall?

Answer 1

tunica intima, tunica media, tunica adventitia

Question 2

What are the characteristics of tunica adventitia?

Answer 2

increase in collagen, no elastin, amounts remain equal

Question 3

What is the trend of % composition between SMC, elastin, and collagen?

Answer 3

• SMC: higher % towards smaller size
• elastin: % remains the same
• collagen: higher % towards larger size

Question 4

The thickness and composition of each lary vary according to what?

Answer 4

vessel and diameter

Question 5

Large arteries contain what?

Answer 5

thick media layer and high amount of elastin

Question 6

What is the trend of elastin in small arteries?

Answer 6

amount of elastin decreases

Question 7

Veins contain what?

Answer 7

thinner media layer and less amount of elastic tissue

Question 8

How does pressure change in the left heart during a cardiac cycle?

Answer 8

1. AV valve opens
2. aortic valve closes
3. aortic valve opens
4. AV valve closes

Question 9

What is diastolic blood pressure (Pd)?

Answer 9

lowest arterial pressure

Question 10

What is systolic blood pressure (Ps)?

Answer 10

highest arterial pressure

Question 11

What is pulse pressure (PP)?

Answer 11

Ps-Pd

Question 12

What is the formula for the mean blood pressure?

Answer 12

• Pa= Pd + .33(Ps-Pd)
• Pa is the average pressure during a complete cardiac cycle

Question 13

What is meant by laminar flow?

Answer 13

NO sounds

Question 14

What are Korotkoff sounds?

Answer 14

sounds produced when an artery is partially constricted and blood flow becomes turbulentcausing the artery to vibrate

Question 15

What is the oscillometry method?

Answer 15

turbulent blood flow occurs when the cuff pressure is greater than the diastolic and less than the systolic

Pd < tuburlance < Ps

Question 16

How is the ausculation method used to measure blood pressure?

Answer 16

• 1st sound = systolic pressure
• 2nd sound= diastolic pressure

Question 17

What are the physiologic factors that determin artieral blood pressure?

Answer 17

cardiac output and peripheral resistance

Question 18

What is cardiac output in arterial blood pressure?

Answer 18

volume of blood being pumped out by the heart

heart rate * stroke volume

Question 19

What are the phyhsical factors that determine arterial pressure?

Answer 19

arterial blood volume and arterial compliances

Question 20

If stroke volume increases, what are the effects on arterial blood pressure?

Answer 20

• within the first cycle, diastolic pressure will remain the same
• every cycle after, diastolic pressure will increase causing the pulse pressure to increase

Question 21

If stroke volume decreases, what are the effects on arterial blood pressure?

Answer 21

• within the first cycle, diastolic pressure will remain the same
• every cycle after, diastolic pressure will decrease causing the pulse pressure to decrease

Question 22

If heart rate increases, what are the effects on arterial blood pressure?

Answer 22

• both diastolic and systolic increase
• pulse pressure has no change b/c there is no change to stroke volume

Question 23

If heart rate decreases, what are the effects on arterial blood pressure?

Answer 23

• both diastolic and systolic decrease
• pulse pressure has no change b/c there is no change to stroke volume

Question 24

If peripheral resistance decreases, what are the effects on arterial blood pressure?

Answer 24

• both diastolic and systolic decrease
• pulse pressure has no change

Question 25

If peripheral resistance increases, what are the effects on arterial blood pressure?

Answer 25

* both diastolic and systolic increase * pulse pressure has no change

Question 26

What is resistance determined by?

Answer 26

blood viscosity, vessel length, vessel radius ## Footnote length and viscosity considered constant

Question 27

How is resistance reduced?

Answer 27

by an increase in radius

Question 28

Vessel resistance is sensitive to what?

Answer 28

diameter and blood flow

Question 29

What vessels have the lowest cross-sectional area (highest resistance)

Answer 29

aortas and large arteries

Question 30

From arteries to arterioles, how is cross-sectional area and resistance blood pressure affected?

Answer 30

cross-sectional area is increased by decreasing resistance

Question 31

What is vascular tone?

Answer 31

degree of constriction relative to its maximally dilated state

Question 32

When do all arterial and venous vessels exhibit some degree of smooth muscle contraction?

Answer 32

under basal conditions

Question 33

How do extrinsic factors regulate blood pressure?

Answer 33

by altering systemic vascular resistance

Question 34

How is vascular tone determined?

Answer 34

by balance of competing vasocinstrictor and vasodilator influences

Question 35

What are intrinsic vascular tones?

Answer 35

* tissue metabolites * local hormones * myogenic -> response to "snap back" * endothelial factors

Question 36

What is vascular stenosis?

Answer 36

abnormal narrowing of an artery ## Footnote decreasing vessel diameter

Question 37

What causes vascular stenosis?

Answer 37

atherosclerosis

Question 38

Focal vacospasm can cause what?

Answer 38

acute stenosis

Question 39

What is critical stenosis?

Answer 39

critical narrowing of an artery that results in reduction in maximal flow capacity

Question 40

What is an example of critical stenosis?

Answer 40

narrowing of an iliac artery decreases flow to piriformis muscle

Question 41

What is meant by blood vessel compliance?

Answer 41

ability of a vessel to distend and increase volume

Question 42

What is the difference between stressed and unstressed volume ?

Answer 42

* stressed volume: that stretched the walls * unstressed volume: the rest

Question 43

What is blood volume compliance quantified as?

Answer 43

change in volume (V) / change in pressure (P)

Question 44

What is the formula for arterial compliance?

Answer 44

Ca = change in Va / change in Pa ## Footnote Va = arterial volume; Pa= arterial pressure

Question 45

What is the formula for arterial elastance?

Answer 45

Ea = change in Pa / change in Va

Question 46

What is the trend of elastance and compliance between arteries and veins?

Answer 46

* artery: increase elastance, decrease complaince * vein: decrease elastance, increase compliance

Question 47

Why is the compliance of arteries much lower than veins?

Answer 47

due to higher elastin and vascular smooth muscle

Question 48

What is the trend between elastin and compliance?

Answer 48

as elastin decreases, compliance increases

Question 49

What is the result of small changes in pressure?

Answer 49

increase in volume chages and compliance

Question 50

What is the action of aortas and large arteries during systole and diastole?

Answer 50

* systole: distend * diastend: recoil

Question 51

How do arteries act as a pressure resevoir?

Answer 51

1. allows continuous blood flow 2. reduces workload on heart because recoil pushes remainder of blood to capillaries 3. reduce blood pressure fluctuation

Question 52

What is the effect of age on compliance?

Answer 52

compliance decreases with age

Question 53

What is the effect of age on systolic and blood pressure?

Answer 53

they both increase with age

Question 54

What are the causes of arterial stiffness?

Answer 54

* increase in collagen * decrease in elastin * decrease in expansion ability

Question 55

What are the physical properties of veins?

Answer 55

* high compliance * low resistance because pressure decreases to get blood back to heart * blood reservoir system * venous valves provide one way to flow towards the right heart

Question 56

What are the biggest determinants of venous return ot the heart?

Answer 56

1. pressure gradient 2. skeletal muscle pump with venous valves

Question 57

What is a skeletal muscle pump?

Answer 57

major mechanism promoting venous return during normal locomotory activity

Question 58

Do veins in large muscles compress or decompress during muscle muscle relaxation/contraction?

Answer 58

* compress during contraction * decompress during relaxation

Question 59

What happens to the respiratory pump during inhalation?

Answer 59

1. thoracic cavity expands 2. pressure in pleural cavities drops 3. pulls air into lungs 4. blood pulled into the IVC and right atrium from smaller veins

Question 60

What happens to the respiratory pump during exhalation?

Answer 60

1. pressure in pleural cavity drops 2. pushes blood into right atrium ## Footnote important during heavy exercise

Question 61

What happens to the respiratory pump during relaxation?

Answer 61

1. pressuredecreases 2. increases blood flow into thoracic veins 3. diaphragm relaxes

Question 62

What happens to the respiratory pump during contraction?

Answer 62

1. pressure decreases 2. increased intrathoracic pressure 3. diaphragm relaxes

Question 63

What is the process of regulated sympathetic vasoconstriction?

Answer 63

increased sympathetic > vasoconstriction> increase venous pressure> increase venous return> increase EDV

Question 64

How does the cardiac suction effect affect venous returns?

Answer 64

increases it

Question 65

Pu;;ing an aorta causes what?

Answer 65

an increase in atrial volume ## Footnote decreasae in atrial pressure drives blood into aorta