oxygen, nutrients, wastes, as many other substances into the interconnecting blood vessels that service body cells.
question
The heart has two receiving chambers
answer
The right atrium and left atrium. Receives blood returning from the systemic and pulmonary circuits.
question
The heart has two main pumping chambers
answer
The right ventricle and left ventricle. Pumps blood around the two circuits.
question
The heart has 4 chambers total
answer
right atrium, left atrium, right ventricle, left ventricle
question
Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______.
answer
prevent the heart from filling properly with blood.
The heart is wrapped by a double-walled sac called the pericardium. The pericardial cavity lies between the parietal and visceral layers of the serous pericardium. It is filled with a very small amount of serous fluid. If additional fluid fills the pericardial space, it adds pressure on the outside of the heart, preventing it from filling normally.
question
The presence of an incompetent tricuspid valve would have the direct effect of causing ______.
answer
reduced efficiency in the delivery of blood to the lungs.
The tricuspid valve separates the right atrium and the right ventricle. It must remain tightly closed during ventricular contraction so blood can be pumped out of the ventricle and into the pulmonary arteries.
question
When an ectopic pacemaker leads to an extrasystole, the ______.
answer
ventricles contract before the atria contract
The conduction system normally follows an ordered excitation route starting with SA node firing, which stimulates atrial contraction. As the Purkinje fibers depolarize and excite the ventricular myocardium, they contract.
question
An abnormal P wave could be indicative of ______.
answer
enlarged atria
The P wave on an ECG tracing represents SA node firing and subsequent atrial depolarization.
question
Hypercalcemia could cause ______.
answer
prolonged T wave
The T wave on an ECG tracing represents ventricular repolarization. Repolarization requires the net efflux of K+ ions. Recall that changes in normal ion concentrations, like Ca2+, in the plasma can affect the ability of other ions to move in and out of the cell.
question
Which of the following cannot trigger tachycardia?
- cardiovascular center
- increased sympathetic stimulation
- increased vagal tone
- increased venous return
answer
increased vagal tone
The vagus nerve carries supplies, efferent parasympathetic motor impulses to the heart, and other major organs. The SA node rate is slowed by impulses from the vagus nerve.
question
The role of the coronary arteries is to __________.
answer
supply blood to the heart tissue
The coronary arteries, as a part of the coronary circulatory route, supply blood to the heart tissue.
question
Which valve is located between the right atrium and ventricle?
- tricuspid valve
- pulmonary semilunar valve
- aortic semilunar valve
- mitral valve
answer
The tricuspid valve separates the right atrium and ventricle.
question
The layers of the heart wall from superficial to deep are: __________.
answer
epicardium, myocardium, and endocardium
question
The heart has __________ chambers and __________ valves.
answer
The heart has four chambers (right atrium, right ventricle, left atrium, and left ventricle) and four valves (mitral valve, tricuspid valve, pulmonary semilunar valve, and aortic semilunar valve).
question
Which of the following does NOT deliver blood to the right atrium?
- superior vena cava
- inferior vena cava
- coronary sinus
- pulmonary veins
answer
pulmonary veins
The pulmonary veins deliver blood to the left atrium, not the right atrium.
question
Which of the following is NOT a difference between the left and right ventricles?
- The left ventricle is a more powerful pump than the right ventricle.
- The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle.
- The left ventricle pumps blood to the systemic circuit, while the right ventricle pumps blood to the pulmonary circuit.
- The walls of the left ventricle are thicker than the walls of the right ventricle.
answer
Since the demands on the left ventricle are so great, it receives the highest percentage of the coronary blood supply.
question
The __________ valve is located between the right atrium and the right ventricle.
answer
The tricuspid valve is located between the right atrium and right ventricle.
question
What structures connect the individual heart muscle cells?
answer
intercalated discs
Intercalated discs connect the heart muscle cells. They include desmosomes (anchoring junctions) and gap junctions (communicating junctions).
question
Which of the following terms refers to a lack of oxygen supply to heart muscle cells?
answer
ischemia
Ischemia refers to a lack of oxygen supply to heart muscle cells.
question
What is the source of ATP for cardiac muscle contraction?
answer
cellular respiration
ATP for cardiac muscle use is produced almost exclusively aerobically in the mitochondria, therefore requiring readily available oxygen. Glucose, fatty acids, or lactic acid may be used as the fuel molecule.
question
Which of the following structures sets the pace of heart contraction?
- bundle branches
- SA node
- AV node
- atrioventricular bundle
answer
The SA node sets the pace or rate of heart contraction.
question
What does the T wave of the electrocardiogram (ECG) represent?
answer
ventricular repolarization
The T wave of the ECG represents ventricular repolarization as the heart rests and prepares to contract again.
question
Which of the following is NOT a factor that regulates stroke volume?
- afterload
- heart rate
- preload
- contractility
answer
heart rate
Heart rate does not affect stroke volume. Heart rate and stroke volume determine cardiac output.
question
The order of impulse conduction in the heart, from beginning to end, is __________.
answer
SA node, AV node, bundle of His, bundle branches, and Purkinje fibers
question
The QRS complex on an electrocardiogram represents __________.
answer
ventricular depolarization
question
In a healthy individual which of the following would be low?
- contractility
- preload
- afterload
- stroke volume
answer
afterload
High afterload is a characteristic of poor cardiovascular health; in a healthy person, afterload would be low.
question
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue?
answer
myocardium
question
Into what vessel does the left ventricle eject blood?
answer
aorta
question
From what vessel do the left and right coronary arteries arise?
answer
aorta
question
Specifically, what part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle?
answer
sinoatrial (SA) node
question
Which portion of the electrocardiogram represents the depolarization wave received from the sinoatrial (SA) node through the atria?
answer
P wave
question
Which of the following would cause a decrease in the contractility of the heart?
answer
increasing extracellular potassium levels
question
What is the period during the cardiac cycle when the ventricles are completely closed chambers and blood volume in the chambers remains constant as the ventricles contract?
answer
isovolumetric contraction phase
question
True/False
The myocardium receives its blood supply from the coronary arteries.
answer
True
question
True/False
Anastomoses among coronary arterial branches provide collateral routes for blood delivery to the heart muscle.
answer
True
question
True/False
The papillary muscles contract after the other ventricular muscles so that they can take up the slack on the chordae tendineae before the full force of ventricular contractions sends blood against the AV valve flaps.
answer
False
question
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________.
answer
pumps blood against a greater resistance
question
Select the correct statement about the heart valves.
- The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
- Aortic and pulmonary valves control the flow of blood into the heart.
- The mitral valve separates the right atrium from the right ventricle.
- The tricuspid valve divides the left atrium from the left ventricle.
answer
The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
question
The condition where fluid accumulation in the pericardial cavity compresses the heart and limits its ability to pump blood is called ________.
answer
cardiac tamponade
question
The ________ layer of the serous pericardium covers the heart.
answer
visceral
question
True/False
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle.
answer
False
question
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells ________.
answer
tetanic contractions might occur, which would stop the heart's pumping action.
question
During contraction of heart muscle cells ________.
answer
some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
question
An older woman complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that the AV node is not functioning properly. What is the suggested treatment?
answer
Surgery to implant an artificial pacemaker
question
True/False
Auricles slightly increase blood volume in the ventricles.
answer
False
question
Damage to the ________ is referred to as heart block.
answer
AV node
question
True/False
Congestive heart failure means that the pumping efficiency of the heart is depressed so that there is inadequate delivery of blood to body tissues.
answer
True
question
True/False
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.
answer
False
question
True/False
Autonomic regulation of heart rate is via two reflex centers found in the pons.
answer
False
question
Hemorrhage with a large loss of blood causes ________.
answer
a lowering of blood pressure due to change in cardiac output
question
The P wave of a normal electrocardiogram indicates ________.
answer
atrial depolarization
question
If the vagal nerves to the heart were cut, the result would be that ________.
answer
the heart rate would increase by about 25 beats per minute
question
Which of these vessels receives blood during ventricular systole?
answer
both the aorta and pulmonary trunk
question
The tricuspid valve is closed ________.
answer
when the ventricle is in systole
question
Select the correct statement about cardiac output.
- Stroke volume increases if end diastolic volume decreases.
- A slow heart rate increases end diastolic volume, stroke volume, and force of contraction.
- If a semilunar valve were partially obstructed, the end systolic volume in the affected ventricle would be decreased.
- Decreased venous return will result in increased end diastolic volume.
answer
A slow heart rate increases end diastolic volume, stroke volume, and force of contraction.
question
During the period of ventricular filling ________.
answer
blood flows mostly passively through the atria and the open AV valves into the ventricles
question
True/False
Proxysmal atrial tachycardia is characterized by bursts of atrial contractions with little pause between them.
answer
True
question
Which of the following is not an age-related change affecting the heart?
- decline in cardiac reserve
- fibrosis of cardiac muscle
- thinning of the valve flaps
- atherosclerosis
answer
thinning of the valve flaps
question
Commotio cordis is heart failure due to a ________.
answer
relatively mild blow to the chest that occurs during a vulnerable interval (2 ms) when the heart is repolarizing
question
A patient was admitted to the hospital with chest pains. On admission, his pulse was 110 and blood pressure was 96/64. According to his history, his normal pulse rate is usually between 80 and 88 and his blood pressure runs from 120/70 to 130/80. Why did these changes in BP and HR occur?
answer
To maintain the same cardiac output, the heart rate would need to increase to compensate for a decreased stroke volume.
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