112 Cardiac Muscle Contraction Flashcards Preview

Cardiovascular > 112 Cardiac Muscle Contraction > Flashcards

Flashcards in 112 Cardiac Muscle Contraction Deck (20)
Loading flashcards...
1
Q

Organization of heart muscle

A
2
Q

Intercalated Discs

A
3
Q

Direction through heart of cardiac conduction

A
4
Q

Myocardial action potential current overview

A
5
Q

Calcium-induced calcium release

A
6
Q

Relationship between depolarization, Ca+2, Tension in cardiac myocyte

A
7
Q

Contractile stuructre of sarcomere

A
8
Q

Thin Filament

A
9
Q

Thick Filament

A
10
Q

Interaction b/w thick and thin filaments

A
11
Q

Cross bridge cycling

A
12
Q

Relaxation of sarcolemma

A
13
Q

Contractility

A

Contractility is the intrinsic strength of contraction independent of loading conditions

Examples of how contractility is potentiated:

  • oAdrenergic Signalling
    • oPhosphorylation of phospholamban
    • oPhosphorylation of troponin I
  • oDigoxin
  • oHeart rate Effects on Contractility
    • oAscending Staircase
    • oRest Potentiation
    • oPost-Extrasystolic Potentiation
14
Q

Adrenergic signaling in cardiomyocytes

A
15
Q

Phospholamban and lusitropy

A
16
Q

Digoxin mechanism

A
17
Q

HR Effects: Ascending Staircase AKA Bowditch effect AKA Treppe

A

Post-Extrasystolic Potentiation:

Premature ventricular contraction (PVC, extrasystole) à less time for [Ca2+] to be removed from cell during relaxation (PVC beat itself is not strong because heart is in relative refractory period) à increased [Ca2+] available during heart beat à increased contractility of the post-PVC beat (post-extrasystole)

18
Q

Preload effect on sarcomere length/Tension

A

Preload is tension “stretch” on the heart prior to contraction.

Passive length-tension: difference explained by titin (rather stiff spring, therefore skeletal with no titin not a real springy)

Starling’s Law: Greater Fiber Length-> More Developed Tension

19
Q

Frank-Starling Curve

A
  • •Increased Calcium Sensitivity at Greater Length, perhaps through greater actin/myosin proximity à More Contraction
  • •Stretch-activated Ca2+ channels à More contraction
  • •Old idea, not correct: more total overlap
20
Q

Afterload

A

Afterload is the load against which muscle must contract.

We approximate afterload clinically with blood pressure.