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: Tissues damaged by myocardial infarction are replaced by connective tissue.
T or F: As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve.
T or F: An ECG provides direct information about valve function.
The P wave of a normal electrocardiogram indicates ________.
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
Damage to the ________ is referred to as heart block.
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
Norepinephrine acts on the heart by ________.
causing threshold to be reached more quickly
Which of the following factors does not influence heart rate?
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
Which vessel(s) of the heart receive(s) blood during right ventricular systole?
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
Normal heart sounds are caused by which of the following events?
closure of the heart valves
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
Blood within the pulmonary veins returns to the ________.
Small muscle masses attached to the chordae tendineae are the ________.
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
Foramen ovale ________.
connects the two atria in the fetal heart
Which of the following is not part of the conduction system of the heart?
The tricuspid valve is closed ________.
when the ventricle is in systole
The AV valves are supported by chordae tendineae so that _________.
regurgitation of blood into the atria during ventricular contraction does not occur
The myocardium is the layer _________.
of the heart that actually contracts
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
The second heart sound is heard during which phase of the cardiac cycle?
The time of day most hazardous for heart attacks is ________.
A slow heart rate increases end ________.
diastolic volume, stroke volume, and force of contraction
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
Commotio cordis is heart failure due to a ________.
relatively mild blow to the chest that occurs during a vulnerable interval (2 ms) when the heart is repolarizing