Circulation and Hemodynamics DSA

Question 1

What receptors are found most commonly found in arterioles? What is their effect

Answer 1

alpha1- adrenergic –> elicit contraction of sm m

Question 2

What receptors are less commonly found in arterioles? What is their effect?

Answer 2

Beta2-adrenergic found in arterioles of skeletal m –> elicit relaxation of sm m and vasodilation

Question 3

What type of vessel has the largest area to blood volume ratio?

Answer 3

capillaries

Question 4

What is perfusion of capillaries determined by?

Answer 4

metabolic needs of tissues controlled by sympathetic NS

Question 5

What type of blood is in veins and venules? What percentage of total blood is there?

Answer 5

unstressed volume of blood 65% at any given time

Question 6

What type of receptors are in venules and veins?

Answer 6

alpha1-adrenergic –> constrict veins and redistribute blood to stresss volume

Question 7

Where is velocity in circulation the greatest?

Answer 7

“at the ends” = largest arteries and veins, closest to the heart

Question 8

What is blood flow determined by?

Answer 8

volume and velocity “more cars in the tunnel, the speed will decrease”

Question 9

What is the equation for blood flow?

Answer 9

Q = deltaP/R

Question 10

What is series resistance?

Answer 10

total resistance is the sum of individual resistances

Question 11

What is paralell resistance?

Answer 11

total resistance is less than any of the individual resistances

Question 12

What is laminar flow?

Answer 12

velocity is greatest at the center and least toward vessel walls more efficient than turbulent flow

Question 13

What is turbulent flow?

Answer 13

when laminar flow is disrupted and takes more energy to drive audible as bruits in arteries or vascular channels and can indicate stenosis

Question 14

What is the eqn for Reynold’s number?

Answer 14

Nr = (rho * d * v) / eta rho = density of blood d = diameter of vessel v = velocity eta = viscosity of blood

Question 15

What is reynold’s number used for?

Answer 15

to predict whether flow will be turbulent or laminar < 2000 = laminar

Question 16

What is shear?

Answer 16

occurs bc velocity is not the same along the vessel wall as it is in the center shear is greatest along wall and lowest at center

Question 17

What is compliance of blood vessels? How is it graphed?

Answer 17

distensibility of a vessel graphed on a volume vs pressure graph

Question 18

What vessels have the greatest and least compliance?

Answer 18

greatest = veins least = arteries

Question 19

What happens if the compliance of a vein is decreased?

Answer 19

vasoconstriction = decreased compliance –> redistribution of blood from unstressed volume to stressed volume (arteries)

Question 20

Where is mean pressure greatest? Where is it the smallest?

Answer 20

largest in aorta smallest in arterioles

Question 21

What is pulse pressure?

Answer 21

difference btw systolic and diastolic pressures

Question 22

What is mean arterial pressure?

Answer 22

2/3(DBP) + 1/3(SBP) = 1/3(pulse pressure) ends up falling closer to diastolic

Question 23

How does arteriosclerosis affect blood pressures?

Answer 23

increases systolic, pulse pressure, and MAP doesn’t affect diastolic

Question 24

How does aortic stenosis affect blood pressures?

Answer 24

systolic, pulse pressure, and MAP will all be decreased

Question 25

How does venous pressure change throughout the body?

Answer 25

lower than arterial and nears zero at vena cava and right atrium

Question 26

How does pulmonary circulation compare to systemic?

Answer 26

much lower pressures flow is the same so resistance is much lower right heart doesn’t have to achieve as large of a pressure

Question 27

How does arterial pressure vary btw recumbent and upright?

Answer 27

fairly consistent recumbent standing = much lower at head and higher at feet

Question 28

What would happen if you had an instantaneous increase in cardiac output or peripheral resistance?

Answer 28

arterial blood volume will continually increase until arterial pressure reaches a level of 200 mm Hg

Question 29

What are the 5 types of microcirculation?

Answer 29

simple diffusion lipid soluble (gases) water soluble osmosis proteins (generally don’t cross except for kidney and intestines)

Question 30

What is the Starling Equation?

Answer 30

Jv = Kf[(Pc-Pi) - (πc - πi)]

Jv = fluid movement

Kf = magnitude of fluid mvnt

Pc = capillary hydrostatic pressure

Pi = interstitial hydrostatic pressure

πc = capillary oncotic pressure

πi = interstitial oncotic pressure

Question 31

What does positive value mean in Starling eqn?

Which variables are typically positive?

Answer 31

favors filtration = fluid from capillary –> tissue

capillary hydrostatic pressure (Pc)

Interstitial oncotic pressure (πi)

Question 32

What does a negative value mean in starling eqn?

What variables are typically negative?

Answer 32

favors absorption = fluid back into capillary

Interstitial hydrostatic pressure (Pi)

Capillary oncotic pressure (πc)

Question 33

What can cause an increased Pc?

Answer 33

venous constriction, increased venous P, edema

Question 34

What can cause a decreased π_c?

Answer 34

decreased plasma protein, severe liver failure, nephrotic syndrome

Question 35

What can cause increased Kf?

Answer 35

burns, inflammation