Vascular Hemodynamics

Question 1

formula for mean arterial pressure

Answer 1

• MAP= CO x SVR

Question 2

if we increase resistance, what is the effect on flow

Answer 2

• decreases flow

Question 3

what is the resistance of the systemic circulation

Answer 3

• high resistance system

Question 4

what is the affect of larger resistances on pressure drops for the same flow

Answer 4

• lead to larger pressure drops

Question 5

relationship between length and resistance

Answer 5

• proportional

Question 6

relationship between viscosity and resistance

Answer 6

• proportional

Question 7

relationship between radius and resistance

Answer 7

• inverse

Question 8

resistors in series

Answer 8

• summate

Question 9

resistors in parallel

Answer 9

• 1/RT to summate

Question 10

each individual resistance in parallel compared to total resistance

Answer 10

• greater than total resistance

Question 11

which part of the vascular system has the highest total resistance

therefore

Answer 11

• arterioles

- largest pressure drop occurs there

Question 12

why do arterioles have the largest pressure drop

Answer 12

• they have the smallest diameter

Question 13

what has the next highest resistance

Answer 13

• capillaries

Question 14

compliance is the measure of _____ of a vessel wall

Answer 14

• distensibility

Question 15

compliance is the measure of the _______ of the vessel

Answer 15

• capacitance

Question 16

decreased compliance means

Answer 16

• increased stiffness

Question 17

which is more compliant (veins or arteries)

Answer 17

• veins

Question 18

compliance formula

Answer 18

• compliance = volume / pressure

Question 19

affect of atherosclerosis and age on compliance

Answer 19

• decreased compliance

Question 20

blood flow is determined by _____ of the vessels

Answer 20

• resistance

Question 21

auto regulation maintains blood flow by altering _____

Answer 21

• resistance

Question 22

myogenic mechanism with decreased blood flow

Answer 22

• decreased blood flow
• less stretch on vascular smooth muscle
• Ca2+ channels close
• vasodilation
• increase in blood flow

Question 23

myogenic mechanism for increase in blood flow

Answer 23

• increase in blood flow
• increased hydrostatic pressure
• more stretch on vascular smooth muscle
• Ca2+ channels open
• vasoconstriction
• decreased blood flow

Question 24

levels of these for vasodilation:

K
H
O2
CO2
adenosine

Answer 24

• K increase
• H+ increase
• O2 decrease
• CO2 increase
• adenosine increase

Question 25

role of histamine

Answer 25

- increases NO | - increases capillary permeability

Question 26

endothelin causes released by

Answer 26

- vasoconstriction | - endothelial cells

Question 27

thromboxane causes released by

Answer 27

- vasoconstriction | - platelets

Question 28

serotonin causes released by

Answer 28

- vasoconstriction | - platelets

Question 29

vasoconstriction mechanisms

Answer 29

- activated of GPCR that increase IP3 - close K+ - activate Ca2+

Question 30

vasoconstriction acts through which receptors

Answer 30

- Gq coupled receptors

Question 31

things that activate vasoconstriction

Answer 31

- NE (via alpha-AR) - angiotensin - vasopressin - endothelin

Question 32

vasodilation mechanism

Answer 32

- activates PKA or PKG | - activates K+ channels or Ca2+ pumps

Question 33

vasodilation acts through which receptors

Answer 33

- Gs receptors

Question 34

things that activate vasodilation

Answer 34

- adenosine - prostaglandins - prostacyclins - epinephrine (via Beta-AR) - nitric oxide - histamine

Question 35

what is the tendency of a hollow organ to recoil toward its original dimensions upon removal of a distending force? what is its relationship to compliance

Answer 35

- elastance | - reciprocal of compliance

Question 36

passive component of vascular compliance

Answer 36

- extracellular matrix proteins

Question 37

active component of vascular compliance

Answer 37

- smooth muscle tone

Question 38

compliance measured on a graph

Answer 38

- slope of the curves

Question 39

venous compliance is decreased by

Answer 39

- alpha 1 adrenergic receptors on venous smooth muscle are activated by catecholamines

Question 40

effect on venous compliance on venous return to the heart

Answer 40

- increases venous return to the heart

Question 41

what provides the most potent regulation of coronary vascular resistance

Answer 41

- metabolic control

Question 42

LaPlace Equation

Answer 42

T = (P x R)/h T=tension P = pressure R = radius h = wall thickness

Question 43

relationship of tension of the vascular wall to the risk of rupture

Answer 43

- as tension increases, risk of rupture increases

Question 44

diagnostic tests to do for aortic aneurysm

Answer 44

- chest CT scan | - echo

Question 45

capillary reserve in myocardial diastole

Answer 45

- there is not capillary reserve

Question 46

physical exam of aortic dissection

Answer 46

- blood pressures uneven in the 2 arms