hi, i am a novice in the field of physiology, with tons of questions about the heart. I hope that my questions will find answers and that others may benefit from them.
1.why do 4 chambers exist in the heart?
2.what contracts first? the left, right atria or both at the same time.
3.what is the main factor responsible for opening, closing the valves? Pressure or electrical activity?
4.when the action potential passes from sa node and travels throughout the heart where is the final destination of the action potential? does it "get used up" or does it dissipate?\
5.when the ventricles contract does this action make the pulmonary, aortic valves open? and how do the valves know when to close once the blood leaves?
6.when the pulmonary artery enters the lungs and branches off, and further branches are made, doesnt this reduce the radius and increase resistance in the vessels?
if so why does rt heart have a lower pressure when there are 300 million alveoli all being supplied by small branches of pulmonary artey ?
thank you all for your help and sorry of these questions are too simplistic..
