The Heart
The second heart sound, __________, marks the point when semilunar valves close.
"dub"
Action potentials in cardiac muscle cells last about ____________________.
250msec
Ventricular systole lasts approximately __________ msec in a normal, resting adult.
270
If undisturbed, the cells of the AV node will depolarize about __________ times per second.
40-60
It takes about __________ msec for the stimulus from the SA node to reach the AV node.
50
Atrial diastole lasts about __________ msec in a resting adult.
700
The stroke volume of the heart is approximately ____________________.
80 ml
Without external interactions, the cells of the SA node depolarize __________ times per minute.
80-100
The free edges of the atrioventricular valves are attached to fibers called ____________________.
chordae tendinae
The Purkinje fibers ____________________.
conduct impulses rapidly
Factors that impact stroke volume and cardiac output include ____________________. a) autonomic activity. b) ion concentration. c) hormone concentrations. d) All of these are true.
d
The most important factor(s) affecting stroke volume is (are) a) end stroke volume. b) ejection fraction c) Both 1 and 2 d) end diastolic pressure.
c
The right atrium receives blood from the ____________________. a) coronary sinus. b) superior vena cava. c) All of these are true. d) inferior vena cava.
c
The bundle branches ____________________. a) conduct impulses to the Purkinje fibers. b) transmit impulses to the left and right ventricles. c) extend to the apex of the heart. d) All of these are true.
d
The left atrioventricular valve is also called the ____________________. a) tricuspid. b) bicuspid. c) mitral. d) Two and three only are true
d
The right and left ventricles are separated from one another by the ____________________. a) coronary sulcus. b) anterior interventricular sulcus. c) posterior interventricular sulcus. d) Both two and three are true.
d
he inner surfaces of the heart are lined with ____________________.
endocardium
The heart has __________ chambers.
four
There are __________ heart sounds.
four
The atrioventricular valves permit blood flow ____________________.
from the atria to the ventricles only
The first electrical event in a normal ECG is the ____________________.
p wave
In a normal resting adult, the effects of the __________ division of the autonomic nervous system dominate.
parasympathetic
the phase found only in cardiac muscle is ____________________.
plateau
The left atrium collects blood from the __________ and empties into the left ventricle.
pulmonary circuit
The left atrium receives blood from the ____________________.
pulmonary veins
When atrial contraction begins, the ventricles are ____________________.
relaxed and in diastole
The moderator band is found in the ____________________.
right ventricle
In an intact heart, the functional pacemaker is the ____________________.
sinoatrial node
The plateau in a cardiac muscle action potential is due to ____________________.
slow calcium channels
Contraction of the chambers of the heart is ____________________.
systole
The first heart sound, "lubb," marks the point when ____________________.
the atrioventricular valve closet
Stroke volume is defined as ____________________.
the blood pumped out of the heart during a single beat
Cardiac output is defined as ____________________.
the blood pumped out of the heart during a single minute
The great cardiac vein drains ____________________.
the region supplied by the anterior interventricular artery
A section through the wall of the heart reveals __________ layer(s).
three
The action potential of cardiac muscles consists of __________ phases.
three
The right atrioventricular valve is also called the ____________________.
tricuspid valve
The heart pumps blood through __________ circuit(s).
two
There are __________ major arteries supplying blood to the heart.
two
The QRS complex represents ____________________.
ventricular depolarization
Atrial systole begins when ____________________.
ventricular diastole ends
The T wave represents ____________________.
ventricular repolarization
Starling's law of the heart refers to the relationship between ____________________.
ventricular stretching and contractile force
The heart muscle is covered by a membrane, the ____________________.
visceral pericardium
The outer layer of the heart is the ____________________.
visceral pericardium
The heart is located ____________________.
Near the anterior chest wall, directly posterior to the sternum.
The dicrotic notch marks the point when the ____________________.
aortic semilunar valve closes
Vessels that carry blood away from the heart are called ____________________.
arteries
When the heart beats, the __________ contract first.
atria
The P wave represents ____________________.
atrial depolarization
The expandable outer portion of each atrium is called a(n)
auricle
The refractory period of cardiac muscles is __________ than skeletal muscles. a) equal to b) longer than c) shorter than d) None of these are true.
b