Cardiac electrophysiology Flashcards
what regulates the movement of blood bw the two chambers of the heart?
atrioventricular valve (AV valve)
the atrial wall contains what compared to the ventricular wall? why is that?
less cardiac muscle tissue; the atria do not need to produce as much force as the ventricles
where does the right half of the heart collect blood from and where does it pump it?
collects from the systemic circuit and pumps into the pulmonary circuit
where does the left half of the heart collect blood from and where does it pump it?
collects from pulmonary circuit and pumps it into the systemic circuit
which ventricle contains more cardiac muscle tissue? why is that?
left ventricle; bc more pressure must be produced to drive blood thru systemic circuit
how are all cardiac muscle cells linked? Where are they located? what does this allow?
electrical synapses; intercalated discs; fast, synchronized responses
cardiac muscle tissue is _________________
autorhythmic
what are the two types of cardiac muscle cells?
contractile and conducting cells
what do contractile cells do?
generate the force that pumps blood; not autorhythmic
what do conducting cells do?
do not generate force. they generate action potentials and rapidly propagate them thru the muscle tissue
in what two groups are conducting cells found in? where are the groups found?
sinoatrial node (SA node) and atrioventricular node (AV node) ; both found in the right atrium
how are most conduction cells organized? what links the SA node to the AV node?
bundles/ tracts; atrial internodal tracts
Where does the AV node propagate action potentials? (2 places)
into the ventricles or to the bundle of His
where else are the action potentials propagated to after the bundle of His?
from bundle of His to the bundle branches and the Purkinje fibers
Propagation of an action potential from the SA node to all other parts of cardiac muscle tissue takes how long at resting heart rate?
220 msec
is propagation slower or faster between conducting cells? is this in all conducting cells?
faster; no the two nodes are 50-100 times slower
why are the nodes slower than the rest of the contractile cells?
slow conduction thru AV node allows the atria to contract before the ventricles
what kind of resting potential do cells in the SA node have? what happens to it once it completes an action potential and what is it called?
not stable; begins a slow depolarization = pacemaker potential
the pacemaker potential is produced by what two types of ion channels?
f-type and t-type channels
when do f and t-type channels open and close?
both open during pacemaker potential and close when the membrane potential reaches threshold again
non-specific cation channels that primarily allow sodium ions to cross the membrane. open @ end of an action potential, inward movement of Na+ depolarizes the membrane
F-type channels
open as the membrane potential nears threshold, allowing Ca+ to move inward, further depolarizing the membrane
t-type channels
what happens to SA action potential at threshold?
L-type Ca+ channels open
what are L-type calcium ion channels?
voltage-gated channels that open gradually, allowing prolonged inward movement of Ca+
when do the L-type channels begin to close?
at the same time as voltage-gated K+ ion channels begin to open.
what do K+ ion channels allow?
the outward movement of K+; repolarizes the membrane
