Module 8 ML-5 Flashcards
What are the three different AP types for cardiac muscle cells
Nodal AP
Conducting cell AP
Contractile cell AP
Why are there different AP types
different types of ion channels
Explain a contractile cell AP
- RMP is close to -90mV due to high potassium leake channels
- threshold reached when AP from neighboring cell arrives at gap junction
- rapid depol due to voltage gated sodium channels
- proloned plateau due to calcium entry through L type calcium channels (and potassium exit)
- repolarization due to voltage gated potassium channels (8-12)
Explain Nodal Cell AP
Sodium entry through funny channels brings membrane depolarization from -60 to -50
- calcium entry through t type channels causes the “pacemaker potential” which brings the membrane to potential to threshold
(-50 to -40)
-depol upstroke due to voltage gated L type calcium channels
-repolarization by voltage gated potassium channels
What are the nodal cells
Sa and AV node
Why are nodal cells’ mV always changing
they are pacemakers
Maximum diastolic potential
most neg value
What is the pacemaker potential
What gets you from MDP to threshold
Explain Fast conducting cell AP
-has all channel types
-includes bundle of his and purkinje
- -60 to -50 due to funny sodium
- -50 to -40 due to T type calcium channels
-fast sodium channels cause depolarization
- L type calcium channels cause the plateau
-repol due to potassium channels
Nodal AP have what kind of channels?
- funny sodium
- t type calcium
- long lasting calcium
-leak/voltage gated potassium
Conducting AP have what kind of channels?
-fast sodium
-long lasting calcium
-leake/voltage gated potassium
Refractory Period of the Heart
-contractile muscle cell AP lasts a long time
-the duration of the contraction is about the smae length as the duration of the AP and refractory period
-this prevents tetanus, sustained contractins of the heart
What does the refractory period allow?
time for ventricles to fill with blood during diastole and in between periods of contraction
