The Heart as a Pump 1 Flashcards
Explain why there is no Tetanic summation in Cardiac mm
Longer action potential. Refractory period ends when the muscle is relaxed.
Depressed ST Segment?
Ischemic Cardiac Disease
Arrhythmias? Cause? Prevention
Patchy fibrosis in cardiac muscle conduct AP, in (out of wave pattern); Long refractory period prevents that. (DRUGS)
How to Cardiac Glycosides increase inotropic state?
The inhibit Na+ K Pump – > intracellular Na+ increase. decreases efflux of Calcium exchanger –> positive inotropic effect
What is inotropic state
Force generated at a specific length..
Things that change the force of contraction
Length
Contractility
After Load
Preload
What affect contractility?
Ca++ # of cells - dead cells duhh
Afterload?
The pressure against which the heart pumps..
Heart Beat Pathways
1) Filling of Ventricle
2) contraction
3) AV valves close
4) Isovoluetric C
5) SL open
6) ejection
7) Isovolumetric R
8) SL Valve C
9) AV valves open
Pressure volume loop (Graph)
Aortic Insufficiency?
Echocardiagraphy
Curve moves to right – at B because high aortic pressure forces blood into the ventricle increasing vol. Remember all parts of heart are filled with blood ( V ); AI - hole in atrial valve; same diff
Wholo Sytolic murmur - what is it?
why?
- murmur through systole
2. leaky av valve
CO = SV * HR
Dominant ?
What can be regulated?
HR - Dominant (4x) - increase = incease CO
CO is not altered to regulate SV or HR
What causes stroke volume to change the most
Filling Stretch, not inotropic
Law of Laplace Coorelation
Meds dilate ventricle - increase R = increased contraction good!
Bad: increase oxygen demand, increased tension can mean collapsed arteries, now must overcome wall tension (ok till a point)
Pressure Volume curve
End systolic pressure - volume relation. P C - Talk
+ intropic effect?
While beat pattern changes, pC always falls along same line. Increased intropic state - shift to left. b/c you ejected more volume.
