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

Question 1

first draw me a pic

draw the myocardial action potential wave form agains the milivolts scale

nothing more

Answer 1

so this represents the action potential in VENTRICULAR mocardial cells

Question 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

Answer 2

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

Question 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

Answer 3

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)

Question 4

repolarization occurs in 2 phases.

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

last one great job so far!!!!!

explain the recovery phase and lable its location

Answer 6

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…..

Question 7

great job!!!

Answer 7