Muscle 7 Flashcards
What kind of cells is cardiac muscle made of?
Myocardial muscle cells
What link myocardial cells together?
Intercalated disks with desmosomes and gap junctions
How do gap junctions link myocardial cells? What does that ensure?
Gap junctions link them electrically and that ensures activation of muscle at the same time
how is contraction initiated in the heart?
spontaneously by autorythmic cells
do autorythmic cells contribute to force
no
how many percent of myocardial cells are autorythmic cells
1%
what causes the action potential spike in autorythmic cells ?
voltage gated L type calcium channels
why are HCN channels considered funny?
because they open because of hyperpolarization and close because of depolarization
how do autorythmic cells spontaneously generate action potentials
HCN channels
whats the membrane potential of autorythmic cells
they don’t have a resting membrane because they are always active, but their returning membrane potential is -60
why are autorythmic cells known as the pacemaker cells
they set the pace of the heart
what is happening during the plateau in contractile cells
potassium is leaving and calcium is coming in in equal amounts
what does long action potential duration (long refractory period) in cardiac cells prevent
summation of contraction
are DHP receptors mechanically coupled to ryanodine receptors in cardiac muscle ?
no
what does excitation coupling look like in cardiac muscle
calcium induced calcium release
