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10 Cards in this Set

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  • Back
Which type of cardiac cells have an action potential that follows the stages of: 0, 2, 3, 4?
Myocytes have stages 0,1,2,3,4
Which type of cardiac cells have a threshold potential of A. -60mV?
B. -40mV?
A. Mechanical cells (these cells have a resting membrane potential of -90mV)
B. Pacemaker cells (these cells have a resting membrane potential of -60mV)
How do myocytes conduct AP between them?
Via gap junctions
What si the neurotransmitter and main hormone involved in sympathetic stimulation of the pacemaker cells? What receptors do they work on?
In sympathetic stimulation, NOR (neurotransmitter) and EPI (hormone) work on B1 receptors of heart. With this sympathetic activity, Ca is forced to enter into the cell faster. This in turn increases HR and force of contraction.
If our heart undergoes vagal stimulation, what does that do to HR and contractility?
Vagal activity decreases both HR and contractility.
K is leaving the cardia contractility cell in every stage but ________.
The 4th. K is coming INTO the myocyte to depolarize it. In phase 3, K moved out rapidly to repolarize the cell and make it more negative (to threshold membrane potential of -60mV). At this threshold membrane potential the cell is ready for another charge!
Acetylecholine stimulates what type of receptors on the heart? What ion does this directly effect and what is its impact on the heart?
Muscarinic receptors. This causes K to exit the heart more slowly thus slowing the AP. This is parasympathetic stimulation.
Atrial kick is associated with which heart sound? What % of more blood is added to ventricle? Is this pathologic? Why?
S4. 30% more blood goes to ventricle w/ atrial kick. An S4 is pathologic because it is the sound of blood hitting a noncompliant ventricle.
If the baroreceptors detect a change in bp, what area of the brain do they stimulate? Where then does sympathetic stimulation originate from?
The adrenal gland is where sympathetic activity originates from.
What is the rate of depolarization of the atria? What about the different escape pacemakers?
Atrial depolarization: 60-80bpm
AV Node: 40-60bpm
Ventricles: 20-40bpm