Circulation & Hemodynamics (DSA)

Question 1

A. Have increased what compared to V.

Answer 1

Elastic fibers, SM, and CT

Question 2

What is the vol. of blood in the A. Called

Answer 2

Stressed Vol. (under pressure)

Question 3

Which artery has the highest resistance to blood flow

Answer 3

Arterioles

Question 4

SM of arterioles is tonically active. What does this mean

Answer 4

Always contracted

Question 5

What is the SM of the arterioles of vascular beds innervated by and what does this cause

Answer 5

Sympathetic N.S. A1R - causes constriction and increased R

Question 6

The SM of skeletal muscle arterioles is innervated by what and what does this do

Answer 6

B1 which relaxes and causes increased BF to skeletal muscles with Sympathetic N.S.

Question 7

How do lipid soluble compounds cross capillaries? What about water soluble (ions)?

Answer 7

Lipid - via simple diffusion

H2O - fenestrations

Question 8

What is selective perfusion controlled by

Answer 8

Symp. N.S.

Question 9

What is the volume in the veins called? What do veins have more of compared to A.

Answer 9

Called unstressed vol.
Veins can hold more Vol.
much less elastic fiber than A.

Question 10

What is the SM of veins innervated by

Answer 10

a1

Question 11

What is the equation to determine the velocity of blood flow

Answer 11

V = Q/A

Question 12

What two factors determine blood flow

Answer 12

1. Pressure difference between the two ends of the vessel

2. Resistance of the vessel itself

Question 13

What is considered the “driving force” of blood flow

Answer 13

The pressure difference at the ends of the vessels

Question 14

Equation to determine pressure difference in a vessel

Answer 14

(Delta)P = QR

Question 15

The Blood flow of a vessel is directly proportional to what

Answer 15

The change in pressure

Question 16

Increased pressure means what to flow? What about R

Answer 16

Increased pressure means increased flow

Increased R means decreased flow

Question 17

Total blood flow is distributed how among parallel vessels

Answer 17

Simultaneously

Question 18

The total resistance of vessels in series is what? What about BF? Where would you find this in the body?

Answer 18

The sum of all resistances of all vessels
Blood flow is same throughout all types of vessels
Found in specific organs

Question 19

For vessels in parallel, how to determine total resistance? What about BF? Where would you find this in the body?

Answer 19

Found in A. Branching off Ao.
Total resistance is less than any single resistance
1/Rt = 1/R1 + 1/R2 + 1/R3 etc.

This means that the pressure and flow in each A. Will be aprox. That of the Ao.

Question 20

For a parallel vessel schematic, what happens if another resistance of the same magnitude is added? What about if a single resistance is increased?

Answer 20

If another one is added, there will be a decreases in total R

However, if one is increased, there will be an increases in total R

Question 21

What does a reynauds # < 2000 mean? What about >3000?

Answer 21

<2000 - laminar flow (no murmurs)

>3000 - turbulent flow

Question 22

Why is reynoles # > in anemia? What about with a thrombus?

Answer 22

Anemia - increased bc of decreased blood viscosity

Thrombi - increased bc of occluded vessel

Question 23

Define vascular compliance and the equation for it

Answer 23

The col. of blood the vessel can hold at a given pressure

C = V/P

Question 24

Increased compliance means what in terms of volume and pressure

Answer 24

Increased volume and decreased pressure

Question 25

Veins can withstand what type of pressure and can hold how much volume? What about A.’s?

Answer 25

V.’s can withstand low pressure and can hold high volume

A.’s can withstand high pressure, but hold less volume

Question 26

A decrease in compliance of the V’s mean a shift where? What about an increase in compliance of the V.’s?

Answer 26

Decreased compliance means a shift to A.’s (stressed volume)

Increased compliance means a shift of blood to V.’s (unstressed volume)

Question 27

Why does pressure decrease in capillaries

Answer 27

Frictional resistance to BF

Filtration of fluid out of capillary

Question 28

What is the equation for MAP

Answer 28

MAP = 2/3(DBP) + 1/2(SBP)

OR

MAP = CO x TPR

Question 29

What does arteriole sclerosis cause in terms of pressure and compliance etc

Answer 29

Increased plaque = decreases r = increased R = decreased compliance = increased systolic, pulse, and mean pressure

Question 30

Define filtration and absorption

Answer 30

Net movement of fluid out of capillary (+)

Net movement of fluid into capillary (-)

Question 31

What is the net pressure

Answer 31

The sum of all pressures of the capillary

Question 32

Define capillary hydrostatic pressure

Answer 32

Favors filtration
Determined by Arteriole and Venule pressure
More affected by venus pressure
Highest at the arteriole end of the capillary

Question 33

Define interstitial hydrostatic pressure

Answer 33

Favors absorption

Question 34

Define capillary oncotic pressure

Answer 34

Due to amount of plasma proteins

Favors absorption

Question 35

Define interstitial oncotic pressure

Answer 35

Favors filtration

Question 36

What is the equation for EF

Answer 36

EF = (EDV - ESV)/(EDV)