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
Q

first draw me a pic

draw the myocardial action potential wave form agains the milivolts scale

nothing more

A

so this represents the action potential in VENTRICULAR mocardial cells

2
Q

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

A

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

3
Q

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

A

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
Q

repolarization occurs in 2 phases.

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

A

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
Q

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

A

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

6
Q

last one great job so far!!!!!

explain the recovery phase and lable its location

A

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
Q

great job!!!

A