Therefore, occurrence of this condition in the left ventricle is because of impeded oxygen blood flow rather than oxygen content per cubic millimeter of blood (Mann, 2010). 5. Draw a normal ECG wave pattern and show how it relates to the action potentials of cardiac muscle cells. What causes the delay between the P. wave and QRS complex?

The delay between P. wave and QRS complex is attributed to the pause that causes the transmission of electrical impulse from the atria to the ventricles to take longer than expected.

6. What is a ventricular ectopic or estrasystole, what area its effect on stroke volume, and what might cause an extrasystole?

Extrasystole refers to the additional beat, or contraction, which causes an interruption in the standard rhythm of the heart rate, which is normally regular. It is caused by electrical discharge originating from other places of the heart rather than the normal sino-atrial node.

7. Are there any dangers in abruptly restoring blood flow to a tissue that has been ischemic for a long time?

It...

This is because such an action may trigger further and greater damage to the affected area- a situation termed as reperfusion injury. Sudden restoration of blood flow to the area increases oxygen flow back to the tissues, triggering increased production of free radicals and reactive oxygen species that tend to damage the cells. Sudden increase in blood flow leads to calcium ion accumulation that may result to fatal cardiac arrhythmias as well as acceleration of self-destruction. In addition, the flow of blood exaggerates inflammation response of the affected tissues, triggering white blood cells to destroy slightly damaged cells that may still be viable elsewhere (Bijlani et al., 2010).
References

Bijlani, R.L. et al. (2010). Understanding Medical Physiology: A Textbook for Medical Students. New Delhi: JP Medical Ltd.

Mann, D.L. (2010). Heart Failure: A Companion to Braunwald's Heart Disease: Expert Consult. New York, NY: Elsevier Health Sciences.