autorhythmicity
the CARDIAC muscle is capable of which of the following?
_________
plateau
PHASE 2 of the cardiac action potential, when the CALCIUM channels remain OPEN and potassium channels are closed, is called the _________ phase
longer, skeletal
which of the following is TRUE of the cardiac action potential?
the cardiac action potential is _________ than the _________ muscle action potential
single, ventricle
the main anatomical difference between the frog heart and the human heart is that the FROG heart has a
_________, fused _________
new, relaxation
the amplitude of the ventricular systole did NOT change with the more frequent stimulation because
a _________ contraction could NOT begin until the _________ phase
refractory, cardiac
which of the following do you think contribute to the INABILITY of cardiac muscle to be TETANIZED?
the long _________ period of the _________ action potential
contract, relax
given the function of the heart, why is it important that cardiac muscle CANNOT reach tetanus?
the VENTRICLES must _________ and _________ fully with each beat to pump blood
ventricular
an EXTRASYSTOLE corresponds to an extra _________ CONTRACTION
decrease
the effect of the PARASYMPATHETIC nervous system on the HEART is to
_________ the heart rate
sympathetic
the branch of the autonomic nervous system that dominates during EXERCISE is
the _________ branch
vagus
parasympathetic stimulation reaches the heart through
_________ nerves, which are cranial nerves
sinoatrial
the usual PACEMAKER of the heart is the _________ node
stopping
EXTREME vagus nerve stimulation affects the heart by
_________ the heart COMPLETELY
sympathetic
vagal escape probably involves _________ reflexes
parasympathetic, more
Research shows that, in the absence of neural and hormonal influences, the SA node generates action potentials at a frequency of approximately 100 times per minute. However, the resting heart rate is approximately 70 beats per minute, which suggests that
right
the SA (sinoatrial) node in the human heart is located in the _________ atrium
homeothermic
organisms that usually maintain the SAME internal body temperature in spite of environmental temperature changes are
_________
homeostasis
the general name for the process that maintains the internal body temperature in humans is _________
autorhythmicity
the electrolytes in a Ringer's solution are required to provide for _________
hyperthermic
an internal body temperature that is ABOVE the normal range is _________
slower
in the 5C ringer's solution, the frog heart
beat _________ than baseline
faster
in the 32C ringer's solution, the frog heart
beat _________ than baseline
decrease
if the human heart were experiencing HYPOTHERMIA, what do you think would be the effect on heart rate?
a _________ in heart rate
cardiac, not
without the ringer's solution, spontaneous _________ action potentials would _________ occur
acetylcholine
the PARASYMPATHETIC nervous system releases _________ to affect heart rate
agonist, decrease
a CHOLINERGIC drug that worked the same as ACETYLCHOLINE would
be an _________ and _________ heart rate
increasing, increasing
norepinephrine affects the heart rate by
_________ the rate of depolarization and _________ the frequency of action potentials
beta
the _________-1 adrenergic receptor binds norepinephrine and epinephrine
decreased, action
pilocarpine DECREASED the heart rate.
typical of cholinergic agonists, it _________ the frequency of _________ potentials
mimic, sympathetic
the effect of ATROPINE was to _________ the _________ nervous system
digitalis, pilocarpine
the modifiers tested that DECREASE the heart rate were
_________ and _________
epinephrine, atropine
to increase the heart rate, the best choices would be
_________ and _________
sarcoplasmic reticulum
which organelle in the cardiac muscle cell stores CALCIUM?
_________ _________
negative, negative
verapamil is a CALCIUM-CHANNEL blocker. Its effects could be described as
_________ choronotropic and _________ inotropic
cytosol
when the cardiac muscle is at rest, where is most of the POTASSIUM found?
in the _________
potassium
resting cardiac muscle cells are most permeable to _________
erratic
the addition of most of the IONS resulted in
an _________ heart rate
negative, negative
the effect of POTASSIUM on the heart is
_________ chronotropic, _________ inotropic
potassium
the ion that had the most pronounced effect on heart rate was _________
decrease, negative
ectopic pacemakers can be caused by excessive LEAKAGE of potassium into cardiac cells, resulting in pacemakers appearing in abnormal locations in the heart muscle. This HYPERKALEMIA (excess potassium) decreases the resting potential of the cardiac muscle