Unit 3 Exam Lab 9 Flashcards
The source of calcium in skeletal muscle is:
the sarcoplasmic reticulum
The source of calcium in cardiac muscle is:
the sarcoplasmic reticulum and extracellular sources
The means of excitation for skeletal muscle is:
nervous system
The means of excitation for cardiac muscle is:
inherent contractions initiated by pacemaker cells
Innervation of skeletal muscle is through
Somatic Nervous System
Innervation of cardiac muscle is through
Autonomic Nervous System
The length of the refractory period in skeletal muscle is approximately:
2-3 msec
The length of the refractory period in cardiac muscle is approximately:
200 msec or more
Which ion is responsible for the long plateau phase of the ventricular muscle action potential?
Calcium
The long plateau phase of the fast response action potential of cardiac muscle:
-is responsible for long refractory period seen in cardiac muscle.
-prevents cardiac muscle from tetanizing
-allows the heart to serve as a pump because the ventricles have time to fill with blood before another contraction can be induced.
-keeps cardiac muscle in the depolarized state so another contraction cannot be initiated until the heart has had time to contract and refill.
-All of the above are true.
all of the above are true
During the cardiac cycle, an extra systole can be induced by electrical stimulation during:
the relative refractory period
The SA-node is innervated by:
both the Parasympathetic and Sympathetic nervous systems
The AV-node is innervated by:
both the Parasympathetic and Sympathetic nervous systems
The atria are innervated by:
both the Parasympathetic and Sympathetic nervous systems
The ventricles are innervated by:
Sympathetic nervous system only
The ______ Nervous System increases the intracellular Ca++, which permits a more rapid & forceful contraction, _____ the rate of re-uptake of Ca++ by sarcoplasmic reticulum following contraction, which _____ plateau phase of ventricular fast response action potential or QT interval making it possible to cause a _____ heart rate.
Sympathetic; increases; shortens; faster
Which of the following statements is/are true?
Group of answer choices
Decreasing the temperature of the fluid bathing the pacemaker caused a decreased rate of contraction and increased stroke volume.
Increasing the temperature of the fluid bathing the pacemaker caused a decreased rate of contraction and increased stroke volume.
Altering only the temperature of the fluid bathing the heart does not affect overall metabolic needs of an organism.
If overall metabolic needs of an organism are not affected, there is no need for CO to increase or decrease.
Decreasing the temperature of the fluid bathing the pacemaker caused a decreased rate of contraction and increased stroke volume.
Altering only the temperature of the fluid bathing the heart does not affect overall metabolic needs of an organism.
If overall metabolic needs of an organism are not affected, there is no need for CO to increase or decrease.
Decreasing the temperature of the fluid bathing the sinus venosus:
-Decreases HR
-Decreases diffusion rate
-Prepotential slope becomes shallower
-Follows Fick’s Law
Increasing the temperature of the fluid bathing the sinus venosus:
-Increases HR
-Increases diffusion rate
-Prepotential slope becomes steeper
-Affects Fick’s Law
Stimulation of the right vagus nerve innervating the turtle heart:
causes the heart rate to decrease
Which of the following statements are true for both increasing the temperature of the fluid surrounding the sinus venosus and stimulating the heart with epinephrine?
Heart rate increases
Filling time decreases.
Vagal stimulation following the addition of atropine results in
no change in the heart rate
During the cardiac cycle, an extra systole can be induced by electrical stimulation during:
the relative refractory period.
relative refractory period
supra-threshold stimuli can result in a muscle contraction
absolute refractory period
no stimulus (no matter how strong) can stimulate muscle to contract during this time
non-refractory
muscle is in polarized state
The compensatory pause is seen because:
the wave of depolarization from the sinus venosus reaches the ventricular muscle during the absolute refractory period of the extra-systole.
You are given a turtle heart preparation with the Stannius Ligatures I and II tied properly. You count the ventricular rate and find it to be 12 beats per minute. Based on what you’ve learned, what rates might you expect to find for sinus venosus and atria, respectively?
20 beats/min, 15 beats/min
Stannius Ligature I
between sinus venosus and atria
Stannius Ligature II
between atria and ventricle
When Stannius Ligatures I and II are tied on a turtle heart, the ______ the lowest (shallowest) prepotential slope, the ______ an intermediate prepotential slope and the ______ the greatest (steepest) prepotential slope.
ventricles have; atria have; sinus venosus has
The two systems of control over cardiac function are Autoregulation via Einthoven’s Law and the nervous system control via somatic nerves.
True or false
False
simulates ventricular muscle cells by decreasing the rate of force development, rate of relaxation, and maximal force developed.
The parasympathetic nervous system
stimulates ventricular muscle cells by increasing the rate of force development, rate of relaxation, and maximal force developed.
The sympathetic nervous system
Vagal tone
Tonic stimulation by the Parasympathetic Nervous System of the SA-node.
Cutting the right vagus nerve: (2)
- eliminates vagal tone
- causes heart rate to increase
- binding of large quantities of acetylcholine to cholinergic receptors in the sinus venosus.
-continuing vagal stimulation until the heart stops beating
-continuing vagal stimulation that causes the prepotential slope of action potentials in the sinus venosus to approach zero.
Vagal arrest
Contraction phase
systole
Filling/relaxing phase
diastole
Result of stimulation during absolute refractory period
Compensatory period
Prepotential of slow response action potential slope approaches zero
Vagal arrest
Alternate pacemakers take over
Vagal escape
