Learning Assessment Quiz (1-8) Flashcards
The cardiovascular system:
Comprises pulmonary and systemic circulations that are in parallel with each other.
Aids in the transfer of heat energy from organs deep within the body to the outside environment.
Transports oxygen from individual cells to the lungs.
Transports carbon dioxide from the lungs to the tissues within organs.
Aids in the transfer of heat energy from organs deep within the body to the outside environment.
The normal sequence of conduction within the heart is:
AV node → SA node → bundle of His → bundle branches → Purkinje fibers.
SA node → AV node → bundle of His → bundle branches → Purkinje fibers.
SA node → bundle of His → AV node → bundle branches → Purkinje fibers.
SA node → bundle of His → AV node → bundle branches → Purkinje fibers.
SA node → AV node → bundle of His → bundle branches → Purkinje fibers.
The rate of sinoatrial (SA) nodal action potential firing increases during exercise. Which of the following mechanisms can cause this increase in rate?
Increased potassium conductance during Phase 4.
Inactivation of fast sodium channels.
Decreasing the slope of Phase 4 by vagal (parasympathetic) activation.
Norepinephrine release increasing calcium conductance into cell.
Norepinephrine release increasing calcium conductance into cell.
A patient complains of becoming “light headed” when he is standing upright. Blood pressure measurements reveal a significant fall in arterial pressure upon standing. Which of the following is a likely explanation of this patient’s condition?
Excessive activation of baroreceptor negative feedback mechanisms.
Reduced cardiac output.
Excessive fluid retention by the kidneys.
Increased heart rate.
Reduced cardiac output.
Which of the following is most responsible for establishing the resting membrane potential in cardiac contractile cells?
Calcium conductance
Sodium conductance
Potassium conductance
Potassium conductance
While sleeping, stimulation of the parasympathetic nervous system results in a/an ___________ heart rate.
decreased
Norepinephrine released from post-ganglionic neurons results in a positive ____________ effect at the SA node.
dromotropic
chronotropic
inotropic
lusitropic
chronotropic
The conduction delay through the AV node is due to all of the following except
the cardiac skeleton
the small size of AV nodal cells
the slow rate of rise in the action potential during Phase 0
the cardiac skeleton
The period of the action potential that is non-responsive, in which no action potential can be elicited is the ________ ________ period. The period of the action potential that is non-responsive to a normal threshold stimulus, but will respond to a supra-threshold stimulus is the ________ ________ period.
Absolute Refractory; Relative Refractory
In the length-tension graph below, which point represents the final length of a ventricular myocyte when contracting against downstream pressure (i.e., an afterloaded contraction)?
5
Cardiac inotrophy is enhanced by
Decreased binding of calcium to troponin-C
Deceased inward sodium current
Inhibition of potassium channels
Increased activation of calcium channels
Increased activation of calcium channels
Which of the following is a result of decreasing cardiac inotropy?
Atrial fibrillation (an irregular and often very rapid heart rhythm (arrhythmia))
Heart failure
AV nodal block
Ventricular fibrillation (an irregular heart rhythm (arrhythmia)
Heart failure
The effect of a positive inotropic drug on the left ventricle would be
An increase in ejection fraction
A reduction in stroke volume
A decrease in its rate of contraction
An increase in the end-diastolic volume of the ventricle
An increase in ejection fraction
The velocity of blood decreases from the aorta down to the capillaries. The primary reason for this drop is due to
Increasing resistance
Increasing cross-sectional area of blood vessels
Increasing cross-sectional area of blood vessels
Which of the following events can lead to a depolarization in a cardiac myocyte (i.e., which can move the cell away from the diastolic or resting membrane potential)?
Decreased sodium conductance
Increased potassium conductance
Decreased calcium conductance
Inhibition of the Na+/K+ ATPase pump in the cell membrane (sarcolemma)
Inhibition of the Na+/K+ ATPase pump in the cell membrane (sarcolemma)
Activation of the sympathetic nervous system (select all correct answers)
increases ventricular contractility.
increases resistance through the AV node.
increases stroke volume.
increases atrial contractility
increases ventricular contractility.
increases stroke volume.
increases atrial contractility
Cardiac inotropy is enhanced by
Activation of alpha-2 receptors.
Decreased release of calcium from the SR.
Decreased calcium binding to Troponin-C.
Phosphorylation of calcium channels.
Phosphorylation of calcium channels.
In ventricular myocytes, a negative lusitropic effect can result from
A rapid influx of chloride.
Increased uptake of calcium by the SR.
Dephosphorylation of phospholamban.
Increased parasympathetic stimulation of the ventricles.
Dephosphorylation of phospholamban.
During excitation-contraction coupling in cardiac myocytes
Calcium binds to myosin to facilitate actin-myosin cross-bridge formation.
During relaxation, calcium is stored inside the cell membrane.
The influx of calcium binds to ryanodine receptors on the SR.
Calcium sparks are directly created when calcium enters via L-type channels.
The influx of calcium binds to ryanodine receptors on the SR.
Which of the following vessel compartments (not within a single vessel) has the highest overall vascular resistance?
Arterioles
A mechanism that helps explain the reason for the increase in tension developed when a sarcomere length is increased includes
Acetylcholinesterase activated release of calcium from the sarcoplasmic reticulum.
Stretch-activation of phospholamban increased calcium uptake into the sarcoplasmic reticulum.
Activation of beta-2 adrenergic receptors increasing inotropy.
Increased calcium affinity of Troponin-C augments myofilament interactions.
Increased calcium affinity of Troponin-C augments myofilament interactions.
Regarding the electrical events in the SA node, the pacemaker current is due to the movement of ions through the _________ channels, while the rapid change in membrane potential (i.e., the action potential) is due to the movement of _________.
HCN, Ca+
In a patient experiencing bradycardia (slow heart rate), which of the following treatments would be beneficial?
An anti-cholinergic drug, such as atropine.
