1.Increased heart rate- Increase contraction in a step wise manner, by accumulating calcium.
2. Post extrasystolic potentiation- The beat that occurs after an extrasystolic beat has increased the force of contraction because extra "Ca 2+" enters the cell duing extrasystole.
3. Also hypoxia and hypercapnea, acidosis depress myocardial contractility.
First point I can understand somewhat. Since many contractions, with out much pause, would accumulate Calcium. Second point I'm assuming is saying the same thing, but I don't understand the terminology. Can anyone explain it clearly. Also hypoxia and hypercapnea directly stimulate vasomotor centre so how does it depress myocardial contractility Thanks