what is the primary function of the cardiovascular system
Delivers oxygen, nutrients, and hormones to organs and tissues
where is the heart located
in the medistinum within the thoracic cavity
which layer of the heart wall is the innermost
endocardium
why does the action potential plateau in cardiac muscle
decreased K+ permeability
if the permeability of the cardiac muscle membrane for K+ decrease, what happens to the action potential
it prolongs the plateau phase
design an experiment to test the effect of varying extracellular CA++ concentrations on cardiac muscle contraction strength
measure contraction strength at different Ca++ levels
which phase of the action potential is characterized by rapid Na+ influx
phase 0
what is the effect of decreased permeability on the action potential plateau
prolongs the plateau
which phase of teh action potential is characterized by the closure of the fast Na+ channels
phase 1
what is the resting membrane potential of a sinus nodal fiber between discharges
-55 to -60 mV
what effect does ACH have on the heart
decreases the rate of rhythm of the sinus node
analyze the role of K+ channels in the action potential of cardiac muscle
they help return the membrane potential to its resting level
critique the role of ACH in cardiac conduction
it decreases the rate of rhythm of the sinus node
what is the threshold voltage for the activation of l-type Ca++ in sinus nodal fibers
-40mV
which fibers connect directly with the surrounding atrial muscle fibers
sinus nodal fibers
what is the total delay in the AV nodal and the AV bundle system
.16 s
what is the velocity of transmission in purkinje fibers
1.5 to 4.0 m/s
why does the action potential plateau in cardiac muscle
deceased K+ permeability
