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Flashcards in Cardiac output in acute stress Deck (18):

Factors that influence Ca sensitivity in cardiac muscle

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


Increased Ca in myocyte leads to what?

increase in force


Compare phosphorylation by PKC and PKA on TnI

PKC decreases velocity and PKA increases velocity


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

Length dependent activation (Frank-Starling effects)
Enhanced contractility, chronotropy


What is a plausible cellular basis for Frank Starling relationship?

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


What impact do positive inotropes have on cardiac muscle?

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


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

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


Response to Phosphorylation of Ca channels
(SAN cells)

Increased HR and improved CO


Response to Phosphorylation of Ca channels (ventricular cells)

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


Response to phosphorylation of Na pump

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


Response to phosphorylation of phospholamban

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


Response to Phosphorylation of FKB

Enhances Ryr receptor mediated calcium release which enhances contractility


Response to Phosphorylation of troponin I

decreased Ca affinity for TnC and enhanced relaxation


What postural accomodations occur when standing up

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


What is isotonic workouts? Isometric?

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


Cardiac changes with isotonic workouts

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


Cardiac changes with isometric workouts

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


Cardiac changes during MI

•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