Chapter 21 Part 2
Pacemaker cells of the SA node depolarize about
80-100 times per minute
How would the heart rate be affected if there were a blockage of the AV node?
The electrical stimuli from the SA node would be normal, but the rate of contraction would slow or be irregular.
In terms of time, at rest one cardiac cycle lasts
a little under 1 second
Which of the following empty directly into the right atrium?
anterior cardiac veins
During one cardiac cycle the ventricles spend most of their time in
diastole
The main pacemaker region of the heart is
in the wall of the right atrium
Valves of the heart open and close due to
pressure changes
The most important factor in ensuring that blood moves in correct order through the heart is (the)
pressure of blood in each of the chambers at any given time
The left atrium receives blood from the
pulmonary veins
Nodal activity of the heart may be influenced or modified by
the autonomic nervous system
The most serious place for a blockage of a coronary artery is
the left coronary artery
Which of the following is true of the contraction of the heart?
Cardiac contractions are coordinated by specialized conductive cardiac muscle fibers
Which of the following conditions would cause the amount of blood entering the ascending aorta with each contraction of the heart to increase?
The amount of blood entering the right atrium of the heart was increased.
Which of the following is true of the coronary arteries?
They originate at the base of the aorta and are the first
The left ventricle pumps blood into the
aorta
Which of the following is an incorrect association?
atrioventricular—aortic valve
Which of the following is a major component of the conduction system located in the inter-ventricular septum?
bundle branches
Blood is supplied to the muscle of the heart through the
coronary arteries
When a clot forms in a coronary vessel and obstructs blood flow to the muscle, the condition is referred to as a(n)
coronary thrombosis
At rest the heart rate is usually ________ by parasympathetic control.
decreased
During their period of systole, the inner volume of the atrial chambers
decreases
Structures in the heart that carry electrical signals from the SA node to the AV node are called
inter-nodal pathways
Which of the following is supplied with blood by the left anterior descending artery?
left ventricle
Blood travels from the left atrium to the left ventricle through the
mitral valve
Papillary muscles of the right ventricle receive a signal to contract from (the)
moderator band
Which of the following valves is assisted in functioning by the papillary muscles?
right atrioventricular valve, tricuspid valve, mitral valve, bicuspid valve
The coronary artery found under the right atrium is (the)
right coronary artery.
The phase of the cardiac cycle during which each chamber contracts and pushes blood into the next structure is
systole
If a small blood clot passes through the heart and heart vessels, where is it most likely to cause damage if it becomes immobilized?
the left coronary artery
During most of ventricular diastole, the
ventricles are filling
The chambers of the heart empty during
ventricular systole
