Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

8 Cards in this Set

  • Front
  • Back
Conductance of what determines the resting membrane potential in cardiac muscle cells?
Conductance to K+
What is the resting membrane potential on the nonpacemaker components of the heart?
90Mv, which is close to the K+ equilibrium potential
What maintains the resting membrane potential?
Na+ K+ ATPase membrane protein
What does it mean when a membrane depolarizes?
There is an inward current that brings in positive charge into the cell.
What does it mean when a membrane hyperpolarizes or repolarizes?
There is an outward current that removes positive charge from the cell.
Describe what happens during each of the following phases of a cardiac action potential:
Phase 0
Phase 1
Phase 2
Phase 0= Upstroke, caused by a rapid transient increase in Na+ conductance, which allows an inward Na+ current to depolarize the membrane(I-Na)
Phase 1= Brief initial repolarizaztion, caused by an outward K+ current, which is due to both chemical and electrical gradients, and decrease in inward Na+ current due in part to a decrease in Na+ conductance
Phase 2= Plateau phase, caused by transient increase in Ca+, conductance and an increase in K+ conductance, which causes inward Ca+ and outward K+ currents(I Ca)
Define Phase 3 and 4 of the cardiac action potential.
Phase 3= Repolarization, caused by decrease in Ca+ conductance and an increase in K+ conductance resulting in a large outward K+ currentI(K+ out).
Phase 4= Resting membrane potential, caused by an equilibrium between outward and inward K+ currents(I K+)
What determines the peak of the cardiac action potential?
Conductance to Na+