MAP Regulation

Question 1

NE effect on HR

Answer 1

mild direct increase in HR and CTY

BUT… reflex bradycardia overall from increased SVR

Question 2

which types of tissue have more density of a1 receptors

Answer 2

skin, splanchnic, renal, skel muscle- non essential

sparse receptors need perfusion even w/ low BP or CO, such as brain, heart, lungs

Question 3

timeframe of hormonal component of arterial baroreflex

Answer 3

onset in 2-3 min, steady in 10-15

Question 4

effect of hormonal component of baroreflex

Answer 4

support SNS, retention of Na and water and vasoconstriction

Question 5

when does capillary oncotic pressure decrease

Answer 5

low plasma proteins (such as albumin) can happen w/ liver failure or malnutrition

Question 6

factors that determine capillary hydrostatic pressure

Answer 6

MAP, capillary flow, ratio of resistance b/w arteriole and venules

Question 7

impact of arteriolar constriction on ultrafiltration

Answer 7

favors absorption, upstream constriction lowers flow to capillaries which reduces hydrostatic pressure and filtration rate

(think about kinking a hose like constricting arterioles)

Question 8

local regulation of vascular tone

Answer 8

metabolites that accumulate during high metabolism cause vasodilation

eg. active skeletal muscle w/ more H+, CO2, adenosine

Question 9

change in venous pressure effect on ultrafiltration

Answer 9

more of an impact than the arteriolar side, in the opposite direction- pro edema because higher capillary hydrostatic pressure

this is because there are less sphincters and other controls on veins

Question 10

when does edema occur

Answer 10

when volume of filtration out of capillaries exceeds capacity of lymphatic system

Question 11

SNS impact on filtration (increase or decrease of SNS activity)

Answer 11

more SNS is pro absorption (higher arterial pressure and less capillary flow)

less SNS is pro edema, arteriole dilation increases flow into capillary and hydrostatic pressure

Question 12

dehydration effect

Answer 12

pro absorption, oncotic pressure is increased due to less plasma water

Question 13

hypoproteinemia effect on ultrafiltration

Answer 13

pro edema, less oncotic pressure

Question 14

define shock

Answer 14

state w/ reduction in systemic perfusion and O2 delivery to tissues- becomes irreversible

results from profound insult to MAP regulation

Question 15

hypovolemic shock impact on PCWP, CO, SVR

Answer 15

decreases (lower preload), decreases (same reason), increases via SNS

Question 16

cardiogenic shock impact on PCWP, CO, SVR

Answer 16

increase (lower CTY), decrease (lower CTY), increased via SNS

Question 17

distributive shock impact on PCWP, CO, SVR

Answer 17

not much impact, increase CO (tachy and low afterload), low SVR (cause of shock)

Question 18

cause of hypovolemic shock

Answer 18

acute blood loss or dehydration- leads to loss of preload and low SV

Question 19

compensation and Tx of hypovolemic shock

Answer 19

tachy and increased SVR

IV saline, maybe blood transfusions

Question 20

cause of cardiogenic shock

Answer 20

insufficient CO- usually low SV from poor CTY (HF or STEMI) or very low/high HR

Question 21

compensation and Tx of cardiogenic shock

Answer 21

increased preload, tachy, SNS increases SVR

tx w/ inotrope, diuretic, ACEi (or other afterload reducer)

Question 22

important physical exam findings on cardiogenic shock

Answer 22

JVD and cold extremities

Question 23

cause of distributive shock

Answer 23

sepsis, anaphylaxis, neurogenic- cause vasodilation and profoundly lower SVR

Question 24

compensation and tx of distributive shock

Answer 24

tachy- usually high SV/CO when combined w/ low afterload

tx w/ fluids, pressors, and underlying cause (eg antibiotics for sepsis)

Question 25

physical exam findings for distributive shock

Answer 25

warm extremities (vasodilation)

Question 26

septic effect on vessels

Answer 26

cause vasodilation and vascular leak- both causing hypotension, increase filtration rate and cause low blood volume

Question 27

sympathomimetic therapy w/ shock, cardio vs distributive

Answer 27

for cardiogenic- need to increase CO, target CTY w/ dobutamine (B1 agonist) and afterload w/ ACEi

for distributive- need to increase SVR, use phenyleprhine (a1 agonist)