sodium and calcium
when the cardiac muscle cell is at rest, the concentration of what is greater on the outside of the cell?
modifiers that affect the force of the contraction of the heart are?
sodium and calcium
the movement of what into the cardiac muscle cell depolarizes the cardiac muscle cell?
modifiers that affect heart rate are?
K+ and NA+
which ion(s) at least initially lowered the frog heart rate in the physioex?
increasing extracellular potassium causes the resting membrane potential to become more positive
what effect does potassium have on the resting membrane potential of the cardiac cell?
the cardiac cell plasma membrane is most permeable to what?
into the cell and decrease heart rate
calcium channel blockers block the movement of calcium_____?
a ______ drug increases the force of the contraction of the heart?
like pilocarpine, it decreases heart rate
muscarine is a poison found in poisonous mushrooms. muscarine binds to acetylcholine receptors and mimics its action. what does it do to heart rate?
beta blockers are used to treat high blood pressure. which receptors are being blocked?
digitalis and atropine
with respect to heart rate, which of the following worked in opposition to each other? (atropine, epinephrine, pilocarpine, digitalis)
digitalis and pilocarpine, atropine and epinephrine
which chemicals had the same effects on heart rate?
epinephrine and norepinephrine
which chemical affected heart rate through the use of cAMP?
acetylcholine, epinephrine, and norepinephrine
the sinoatrial node has receptors for what?
an antagonist and decrease heart rate
an adrenergic drug that worked in opposition to epinephrine would?
have temperature fluctuations that coincide with the external temperature and lack internal homeostatic temperature regulatory mechanisms
organisms that are poikilothermic ?
which part of the human body regulates temperature?
vasodilation and sweating
heat-releasing mechanisms include what?
for the frog heart, temperature and heart rate are?
the heart rate would increase
if the human heart were experiencing hyperthermia, what would happen to heart rate?
cations, anions, and electrolytes
ringer's solution contains which of the following?
increase the heart rate and increase the force of contraction
the effect of the sympathetic nervous system on the heart is to?
the parasympathetic branch
which branch of the autonomic nervous system dominates after a large meal?
in the right atrial wall of the human heart
the sinoatrial node is located where?
a decrease in heart rate, and eventually a temporary cessation of the heartbeat
excessive vagal stimulation of the heart will result in what?
the heart rate slowed and eventually stopped
when vagus nerve stimulation was applied to the frog heart, what happened?
the part where the heart resumed beating
what part of the trading illustrates vagal escape?
about 100 beats per minute
if the vagus nerve were severed, what would be the approximate heart rate?
the SA node
which part of the heart conduction system has the fastest rate of spontaneous depolarization?
the autorhythmicity of cardiac pacemaker cells is made possible by the reduced permeability of what?
potassium exiting the cell
depolarization of cardiac muscle is due to what?
is longer than the total refractory period for skeletal muscle
the total refractory period of cardiac muscle is?
wave summation and tetanus
skeletal muscle is capable of what, which cardiac muscle is not capable of?
did not increase the height of the ventricular systole wave
delivering single shocks in succession to stimulate the frog heart had what result?
an extrasystole and an extra contraction of the ventricles
the doublet that results with more frequent stimulate of the frog heart represents what?
a compensatory pause followed
when the ventricles beat rapidly in succession, what happened?
extrasystoles were produced
when multiple stimuli were applied at 20 stimuli/sec, what happened?