Cardiac output in acute stress

Question 1

Factors that influence Ca sensitivity in cardiac muscle

Answer 1

pH, temperature, sarcomere length, contractile protein phosphorylation, caffeine

Question 2

Increased Ca in myocyte leads to what?

Answer 2

increase in force

Question 3

Compare phosphorylation by PKC and PKA on TnI

Answer 3

PKC decreases velocity and PKA increases velocity

Question 4

Mechanisms by which the heart moderates its performance throughout the day include:

Answer 4

Length dependent activation (Frank-Starling effects)

Enhanced contractility, chronotropy

Question 5

What is a plausible cellular basis for Frank Starling relationship?

Answer 5

At longer lengths, the actin and myosin may actually be closer to each other and more cross bridges can form

Question 6

What impact do positive inotropes have on cardiac muscle?

Answer 6

NE or catecholamines effect heart so that at the same length there is more force

Question 7

On a cellular level, Beta adrenergic signaling ultiimately results in what?

Answer 7

Activation of PKA which phosphorylates Ca channel, TnI, RyR2 and/or PLB

Question 8

Response to Phosphorylation of Ca channels

SAN cells

Answer 8

Increased HR and improved CO

Question 9

Response to Phosphorylation of Ca channels (ventricular cells)

Answer 9

increased Ca entry, increased force of contraction thus improved ejection fraction

Question 10

Response to phosphorylation of Na pump

Answer 10

increased Ca efflex vis Na/Ca exchanger which enhances relaxation and diastolic filling

Question 11

Response to phosphorylation of phospholamban

Answer 11

Disinhibition of SR calcium pump (SERCA2) which increases SR calcium load and improves diastolic filling

Question 12

Response to Phosphorylation of FKB

Answer 12

Enhances Ryr receptor mediated calcium release which enhances contractility

Question 13

Response to Phosphorylation of troponin I

Answer 13

decreased Ca affinity for TnC and enhanced relaxation

Question 14

What postural accomodations occur when standing up

Answer 14

Increased venous return from skeletal muscles increases EDV which increases stroke volume

Question 15

What is isotonic workouts? Isometric?

Answer 15

isotonic= bike/jog/swim/ Isometric= lifting weights

Question 16

Cardiac changes with isotonic workouts

Answer 16

Peripheral vascular resistance decreases and CO goes up, which increases venous return. Increased HR and increased inotropy

Question 17

Cardiac changes with isometric workouts

Answer 17

Increased peripheral vascular resistance maintains blood flow to exercising muscle group. Increased HR. NO increase in CO

Question 18

Cardiac changes during MI

Answer 18

•Loss of functional myocardium, Increased catecholamine surge
(Sweating, tachycardia, ± hypertension), Increased inotropy to maintain CO despite increase BP (afterload), Heterogeneous cellular environment,Local /regional changes in pH, membrane potential and secondary effect on cytosolic calcium