chapter 9- cardiac pump Flashcards
what is syncytium
mass resulting forma fusion of cell
- atrial and ventricular syncytium
what is the fibrous insulator
by fibrouds tissue, exists btwn atrium and ventricle
what do cardic cells have
- actin and myosin
- intercalated disk
what are intercalated disk
low resistance disk btwn the cells
1/400 the resistance of cell membrane
what is the resting membrane potential of cardiac muscles
-85 to 95 millivolts
what is the volts of the action potential
105 millivolts total ( from -85 to +20 mV)
how long does the plateau last
.2 to -.3 sec in ventricular muscle ( but is much longer than skeletal m.)
how do you power the heart
action potentials
what is phase 0 of the ventricular ap
fast na channel open
what is phase 1 of the ventricular ap
transient outward K channels open
what is phase 2 of the ventricular ap
ca channels open more this ca is used for muslces contractions
what is phase 3 of the ventricular ap
k channels open more
what is phase 4 of the ventricular ap
resting membrane potential
where is ca released from
saroplasmic reticulum
extracellular fluid
what does the the released of the extracellular fluid ca do
1 works with the contractions
2 stimulated the sarcoplasmic reticulum to make mroe Ca++
how does the Ca come form the extracellular fluid
through t tubules
what is tid
slide 7
what is diad
slide 7
how does skeletal m. increase force development in the m.
recruit more motor units via motor neurons
how does cardia m. increase the force of contraction
increase intracellular calcium unmask more binding sites
how long is the conduction of the ap along both atrial and ventriclar m.
is about .3 to .5 m/sec
how long is the conduction of the ap in the purkinje fibers is
about 4 m/sec
what is the absolute refractory
this is during this time cardiac m. cannont be re excited
how long is the absolute refractory in the ventricles
.25-30 sec
