The "lub" sounds of the heart are valuable in diagnosis because they provide information about the function of the heart's pulmonary and aortic valves.
The dicrotic notch refers to the brief rise in pressure caused by the closure of the AV valves during ventricular systole.
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle.
Congestive heart failure means that the pumping efficiency of the heart is depressed so that there is inadequate delivery of blood to body tissues.
Chronic release of excess thyroxine can cause a sustained increase in heart rate and a weakened heart.
To auscultate the aortic valve, you would place your stethoscope in the ________.
second intercostal space to the right of the sternum
The source of blood carried to capillaries in the myocardium would be the ________.
When the heart is beating at a rate of 75 times per minute, the duration of one cardiac cycle is ________ second(s).
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
decreased delivery of oxygen
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
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
Blood ejected from the ventricles enters which of these vessels during ventricular systole?
both the aorta and pulmonary trunk
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________.
noticing the thickness of the ventricle walls
Select the correct statement about the heart valves.
The AV valves are supported by chordae tendineae so that they
Select the correct statement about the function of myocardial cells.
The all-or-none law as applied to cardiac muscle means that the
Select the correct statement about the structure of the heart wall.
The myocardium is the layer of the heart that actually contracts.
Hemorrhage with a large loss of blood causes ________.
a lowering of blood pressure due to change in cardiac output
Compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
The deflection waves in an ECG tracing include ________.
the T wave, which indicates ventricular repolarization
During the period of ventricular filling ________.
blood flows passively through the atria and the open AV valves
The effect of endurance-type athletic training may be to lower the resting heart rate. This phenomenon ________.
is caused by hypertrophy of the heart muscle
If a significant amount of connective tissue were to develop connecting the visceral and parietal pericardial layers together, which of the following would be a likely consequence?
interference with normal mechanical cardiac activity
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
Select the correct statement about cardiac output.
A slow heart rate increases end diastolic volume, stroke volume,and force end of contraction
During contraction of heart muscle cells ________.
some calcium enters the cell from the extracellular space and
The left ventricular wall of the heart is thicker than the right wall in order to ________.
pump blood with greater pressure
Isovolumetric contraction ________.
refers to the short period during ventricular systole when the ventricles are completly closed chambers