Myocardial action potential (this is what we'll go by) Flashcards Preview

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Flashcards in Myocardial action potential (this is what we'll go by) Deck (7)
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1

first draw me a pic

draw the myocardial action potential wave form agains the milivolts scale

nothing more
 

so this represents the action potential in VENTRICULAR mocardial cells

2

The action potention is generated when the membrane potential is partially depolarized from the resting level (EM) to the threshold potential (ET) label this area on your pic

note the resting potential (-70 to -90)  this is also refered to as phase 4 but we'll get there shortly

3

after the impulse reaches this resting membrane potential the ensuing rapid Phase 0 occurs. this is the phase of DEPOLARIZATION. lable this on your graft and writs the ionic movement across the membrane

Phase 0 is mediated by Na+ entry into the cells due to a marked increase in the # of open Na+ channels in the cell membrane

---SO Na+ INTO THE CELL

(thus K+ out)

4

repolarization occurs in 2 phases.

lable them and describe what is occuring in them . Ex which ions crossing where etc.

Repolarization occurs in phases 1 and 3 and results from K+ EXIT from the cells as the Na+ channels are closed and K+ channels open

phase 1 is early repolarization

Phase 3 is repolarization

5

next draw and explain the "plateau phase" and of course lable it correctly

reflects the slow entry of Ca++ into the cells, which counteracts the effects of K+ exit

6

last one great job so far!!!!!

explain the recovery phase and lable its location

Na+ leaves and K+ reenters the cell during phase 4 via the Na+-K+-ATPase pump and all is back to the resting membrane potential awaiting another stimulus.....

7

great job!!!