Circulation And Hemodynamics

Question 1

What is the site of the highest resistance and largest drop is pressure?

Answer 1

Arterioles

Question 2

Composition of capillaries

Answer 2

Single layer of endothelial cells surrounded by basal lamina

Question 3

How is perfusion of capillaries determined?

Answer 3

By metabolic needs of the tissue and the tone of the arteriolar smooth muscle

Question 4

Velocity of blood flow

Answer 4

V=Q/A
Speed at which blood travels

Flow=speed and number of blood traveling

Question 5

Flow equation

Answer 5

DeltaP/R

Question 6

Poiseuille’s law

Answer 6

(8ln)/(piR^4)

Question 7

Series resistance

Answer 7

Resistance is the sum of the forces

Question 8

Parallel resistance

Answer 8

Resistance is 1/sum of the resistances and is lower than all individual resistances

Question 9

Bruits

Answer 9

Heard when turbulent flow occurs in an artery or other vascular channel

Question 10

Reynold’s number

Answer 10

Nr=(pdv)/n

Density
Diameter
Velocity
Viscosity

<2000 predicts laminar flow while >2000 predicts turbulent flow

Question 11

Mean arterial pressure

Answer 11

2/3 DBP + 1/3 SBP

DBP + 1/3 pulse pressure

Question 12

Arteriosclerosis

Answer 12

Plaque deposits form in arterial walls - decreases diameter and compliance of vessels, increases SBP, pulse pressure, and MAP (no large influence on DBP)

Question 13

Lipid soluble microcirculation

Answer 13

O2, CO2. Driven by partial pressure gradient for that gas - also determined by the surface area of capillaries.

Question 14

Water soluble microcirculation

Answer 14

Ions, glucose, AA
Diffusion doesn’t occur well. Limited movement between clefts of endothelial cells. Limits SA available for movement of molecules.

Question 15

Osmosis of microcirculation

Answer 15

V important.

Driven by hydrostatic and osmotic pressure differences btwn lumen of vessel and interstitial space

Question 16

Proteins in microcirculation

Answer 16

Generally don’t cross except in kidney and intestine where fenestrations in the capillaries will allow for limited movement of protein molecules

Question 17

Starling equation

Answer 17

IV=Kf [(Pc-Pi)-(piC-piI)]

Question 18

Kf

Answer 18

Determines magnitude of fluid movement

Question 19

Pc

Answer 19

Favors filtration based on fluid pressure

Hydrostatic capillary pressure

Question 20

Pi

Answer 20

Opposes filtration

Hydrostatic interstitial pressure

Question 21

PiC

Answer 21

Opposes filtration

Capillary oncotic pressure

Question 22

PiI

Answer 22

Favors filtration

Interstitial oncotic pressure

Question 23

How will Pc impact lymph filtration

Answer 23

Pc can increase with venous pressure, heart failure, and ECF volume expansion and will cause an increase in lymph filtration

Question 24

How will piC impact lymph filtration

Answer 24

piC will decrease from decrease plasma protein concentration, severe liver failure, protein malnutrition, or nephrotic syndrome and this will increase lymph filtration

Question 25

How will Kf impact lymph filtration

Answer 25

Kf will be increase by burns or inflammation and will increase the lymph filtration

Question 26

How does impaired lymphatic drainage affect lymph filtration?

Answer 26

It will increase it Can be caused by standing for long periods, removal or LNs, and parasitic infections

Question 27

Active hyperemia

Answer 27

Blood flow is proportional to metabolic activity I.e. blood flow is increased to exercising SKM

Question 28

Reactive hyperemia

Answer 28

An increase in blood flow in reaction to a period of decreased blood flow

Question 29

Myogenic hypothesis

Answer 29

Can explain autoregulation - states if vascular SM is stretched it will react and contract

Question 30

Metabolic hypothesis

Answer 30

O2 delivery is matched to O2 consumption

Question 31

local metabolic control is most important for which types of circulation

Answer 31

Coronary, cerebral, pulmonary, renal, and SKM when exercising

Question 32

Sympathetic control is most important for which types of circulation

Answer 32

SKM at rest and skin circulation

Question 33

Mechanisms for generating heat

Answer 33

``` Thyroid hormones (stimulate Na/K+ and increase metabolic rate) Sympathetic nervous system, shivering (started by posterior hypothalamus) ```

Question 34

Mechanisms for dissipating heat

Answer 34

Coordinated by anterior hypothalamus to decrease symp outflow through arterioles and shunt blood to venous plexuses near surface of skin Also increase sympathetic cholinergic activation of sweat glands