If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
decreased delivery of oxygen
T or F: Paroxysmal atrial tachycardia is characterized by bursts of atrial contractions with little pause between them.
T or F: As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve.
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
threshold is reached more quickly and heart rate would increase
Which of these vessels receives blood during ventricular systole?
both the aorta and pulmonary trunk
Select the correct statement about the function of myocardial cells.
The entire heart contracts as a unit or it does not contract at all
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________.
noticing the thickness of the ventricle walls
Isovolumetric contraction ________.
refers to the short period during ventricular systole when the ventricles are completely closed chambers
To auscultate the aortic semilunar valve, you would place your stethoscope in the ________.
second intercostal space to the right of the sternum
The condition where fluid compresses the heart and limits its ability to contract is called ________.
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells, ________.
tetanic contractions might occur, which would stop the heart's pumping action
If the vagal nerves to the heart were cut, the result would be that ________.
the heart rate would increase by about 25 beats per minute
The left ventricular wall of the heart is thicker than the right wall in order to ________.
pump blood with greater pressure
Which of the events below does not occur when the semilunar valves are open?
Ventricles are in diastole
Hemorrhage with a large loss of blood causes ________.
a lowering of blood pressure due to change in cardiac output
The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is ________.
The source of blood carried to capillaries in the myocardium would be the ________.
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________.
pumps blood against a greater resistance
Which of the following is not an age-related change affecting the heart?
thinning of the valve flaps
The AV valves are supported by chordae tendineae so that _________.
regurgitation of blood into the atria during ventricular contraction does not occur
Compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
During the period of ventricular filling ________.
blood flows passively through the atria and the open AV valves into the ventricles
During contraction of heart muscle cells ________.
some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores