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181 terms

The Heart

Chapter 20
STUDY
PLAY
The space between the pleural cavities is called the ________.
mediastinum
In cardiac muscle
at least half of the calcium ion required for contraction comes from outside the cell.
At a heart rate of 60 beats/minute, a cardiac cycle lasts
1 second
Which of the following is greater during left ventricular systole?
the peak pressure in the ventricle
If there is a complete block between the SA node and the AV node, how would the ECG be affected?
The rate of P waves will be faster than the rate of QRS complexes.
The ________ separates the two atria.
interatrial septum
________ is the symptom generally brought on by coronary ischemia.
angina pectoris
The term ________ refers to blockage in the coronary circulation.
coronary artery disease
Oxygen is removed from blood as it flows through the ________ circuit.
systemic
Cardiac muscle cells and skeletal muscle cells differ in a few ways. Which of the following is not one of them?
Cardiac muscle cells lack transverse tubules.
Rupture of the papillary muscles in the left ventricle may result in
bicuspid regurgitation.
mitral regurgitation.
bicuspid prolapse.
mitral valve prolapse.
The wall of the left ventricle is thicker than the right because
both the left ventricle does more work than the right ventricle and the left ventricle produces a higher pressure than the right.
Blood returning to the heart from the pulmonary circuit first enters the
left atrium
Compared to the right ventricle, the left ventricle has all the following characteristics, except that it
pumps a greater volume
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes.
What effect would compressing the inferior vena cava just below the diaphragm have on cardiac function?
Sympathetic stimulation of the heart would increase.
Artery is to ________ as vein is to ________.
efferent; afferent
Intercalated discs serve to transfer ________ from cell to cell.
the force of contraction
ionic currents
action potentials
The foramen ovale in the fetal heart is located in the
interatrial septum
Blood is supplied to the myocardium by
the coronary arteries.
Contractions of the papillary muscles
prevent the atrioventricular valves from reversing into the atria.
The inferior point of the heart is called the ________.
apex
The pulmonary semilunar valve prevents backward flow into the
right ventricle
When the left ventricle contracts, the diameter of the ventricular chamber
decreases
Blood flowing into the heart from the venae cavae flows next through the ________ valve.
tricuspid
The circumflex branch and the anterior interventricular artery are branches of the
left coronary artery
The atrioventricular valves permit blood flow
in one direction only
In the middle of the thoracic cavity is a region occupied by the heart, great vessels, thymus, esophagus, and trachea called the
mediastinum
The right ventricle pumps blood to the
right and left lungs
The ________ valve prevents backward flow into the left atrium.
bicuspid
The left ventricle pumps blood to the
aorta
As blood leaves the right ventricle it passes through the ________ and then into the pulmonary trunk.
conus arteriosus
The pulmonary veins carry blood to the
heart
The first blood vessels to branch from the aorta are the ________ arteries.
coronary
When the semilunar valves close, the AV valves then
open
The cusps (leaflets) of atrioventricular valves attach directly to
chordae tendineae
Most of the middle layer in the heart wall is composed of
cardiac myocytes
The bicuspid or mitral valve is located
between the left atrium and left ventricle.
The following is a list of vessels and structures that are associated with the heart.

1. right atrium
2. left atrium
3. right ventricle
4. left ventricle
5. venae cavae
6. aorta
7. pulmonary trunk
8. pulmonary veins
5, 1, 3, 7, 8, 2, 4, 6
The heart pumps approximately ________ liters of blood each day.
8000
Blood returning to the heart from the systemic circuit first enters the
right atrium
The right atrium receives blood from the
coronary sinus, superior vena cava, and inferior vena cava.
The earlike extension of the atrium is the
auricle
The structure that permits blood flow from the right atrium to the left atrium in the fetal circulation is the
foramen ovale
The coronary sulcus is a groove that
marks the border between the atria and ventricles.
When the left ventricle contracts, the distance from the apex to the base
decreases
The ________ deliver(s) blood to the myocardium.
both right coronary artery and left coronary artery
Coronary veins empty into the
right atrium
The function of the atrium is to
both collect blood and pump blood to the ventricle.
Blood leaves the right ventricle by passing through the
pulmonary valve
The visceral pericardium is the same as the
epicardium
The pulmonary arteries carry blood to the
lungs
The interventricular sulci and coronary sulcus contain
ateries, fat, veins
The heart is roughly the size of
a man's clenched fist
Which of the following descriptions matches the term near the left fifth intercostal space?
apex
There are ________ pulmonary veins.
4
The marginal branch and posterior interventricular branch are branches of the
right coronary artery
The great and middle cardiac veins drain blood into the
coronary sinus
The term used to describe fluid collecting in the pericardial cavity that restricts the movement of the heart is known as
cardiac tamponade
The connective tissue fibers of the myocardium
help distribute the forces of contraction.
add strength and prevent overexpansion of the heart.
provide elasticity to help return the heart to its normal size.
provide physical support for cardiac muscle.
Blood is supplied to the left atrium by the
left coronary artery
Excess fluid in the ________ causes cardiac tamponade.
pericardial cavity
In order to perform a CABG, a cardiac surgeon must
both open the pericardial sac and visualize the visceral pericardium.
The heart lies within the ________.
pericardial cavity
The superior portion of the heart where major blood vessels enter and exit is the ________.
base
An equivalent term for epicardium is ________.
visceral pericardium
The wall of the ________ rests on the diaphragm.
right ventricle
The space between the pleural cavities is called the ________.
mediastinum
The ________ is shared by the two ventricles.
interventricular septum
Muscular ridges on the inner surface of the ventricles are called ________.
trabeculae carneae
The ________ circuit carries blood to and from the lungs.
pulmonary
The ________ circuit carries blood from the aorta to the right ventricle.
systemic
________ carry blood away from the heart.
arteries
________ carry blood toward the heart.
veins
The ________ covers the outer surface of the heart.
epicardium
The muscle layer of the heart is the ________.
myocardium
The ________ lines the chambers of the heart, covers the heart valves, and is continuous with the endothelium.
endocardium
Oxygen is added to blood as it flows through the ________ circuit.
pulmonary
In a procedure known as balloon ________, an inflatable balloon at the end of a catheter is used to press plaque back against the vessel wall.
angioplasty
A procedure in which a length of the patient's vein or artery is used to create a detour around an obstruction in a coronary artery is called ________.
CABG
A fine tubular wire mesh called a ________ may be inserted into a coronary vessel, holding it open.
stent
As the left ventricle contracts, it bulges into the ________.
right ventricular cavity
The ________ is a remnant of an important fetal blood vessel that once linked the pulmonary and systemic circuits.
ligamentum arteriosum
The heart has four chambers, two small thin-walled ________ and two large muscular ________.
atria, ventricles
The long-term success rate of angioplasty greatly increases with the use of stents.
true
A slower-than-normal heart rate is called ________.
bradycardia
In cardiac muscle
at least half of the calcium ion required for contraction comes from outside the cell.
A faster-than-normal heart rate is called ________.
tachycardia
At a heart rate of 60 beats/minute, a cardiac cycle lasts
1 second
Which of these comparisons between skeletal and heart muscle is false?
both rely entirely on oxidative metabolism for energy.
Which of the following is greater during left ventricular systole?
the peak pressure in the ventricle
If there is a complete block between the SA node and the AV node, how would the ECG be affected?
The rate of P waves will be faster than the rate of QRS complexes.
If the connection between the SA node and AV node becomes blocked,
the ventricles will beat more slowly
The long plateau phase of the cardiac muscle action potential is due to
calcium channels remaining open
An increase in the rate of action potentials from baroreceptors will reflexly lead to
both decrease in heart rate and decrease in blood pressure.
During the T wave of the electrocardiogram, the ventricles are
both repolarizing and relaxing.
Depolarization of the atria corresponds to the EKG's
P wave
As a result of the long refractory period in the cardiac action potential, cardiac muscle cannot exhibit
tetany
The following are structural components of the conducting system of the heart.

1. Purkinje fibers
2. AV bundle
3. AV node
4. SA node
5. bundle branches

The sequence in which excitation would move through this system is
4, 3, 2, 5, 1
The normal pacemaker of the heart is located in the
SA node
The P wave of the electrocardiogram is a signal from
depolarization of the atria
The T wave on an ECG tracing represents
ventricular repolarization
Depolarization of the ventricles is represented on an electrocardiogram by the
QRS complex
Cardiac cells damaged by infarction will show which of the following?
release of troponin T and I into the circulation.
switch to anaerobic metabolism.
release of enzymes into the circulation.
release of MB-CK into the circulation.
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
What does the ECG wave tracing represent?
electrical activity in the heart
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
A heartbeat lasts
370 msec
If the pacemaker cells in the SA node become more permeable to potassium ions, the
both heart rate will decrease and membrane will hyperpolarize
Analysis of the electrocardiogram can reveal all of the following, except the
stroke volume
When a blood clot forms on a ruptured plaque in a coronary artery, the condition is referred to as a(n)
coronary thrombosis
AV nodal cells are poorly interconnected compared to contractile cells but they have bigger diameters.
The first part of the statement is true but the second part is false.
Abnormally slow depolarization of the ventricles would most change the shape of the ________ in an ECG tracing.
QRS complex
The property of heart muscle to contract in the absence of neural or hormonal stimulation is called ________.
automaticity
Cells that spontaneously make action potentials make up ________ tissue.
pacemaker
The structures responsible for distributing excitation to the contractile cells are ________.
conducting fibers
The two types of cardiac muscle cells involved in a normal heartbeat include specialized cells of the ________ system and ________ cells.
conducting, contractile
A heart murmur might be caused by
aortic valve stenosis or mitral valve insufficiency or pulmonic valve insufficiency.
The relaxation phase of the cardiac cycle is called ________.
diastole
________ is when the heart can't maintain adequate cardiac output.
heart failure
As the heart rate slows, ________ gets longer.
diastole
If the connection between the vagus nerve and the heart is cut, which of these changes will occur?
NONE OF THE ABOVE
NOT: (stroke volume will decrease, heart will beat slower, cardiac output will decrease, nodal fibers will depolarize more slowly )
During the isovolumetric phase of ventricular systole, the
atrioventricular valves and semilunar valves are closed.
The one-way nature of the left AV valve prevents blood flow from _________.
the left ventricle to the left atrium
The closing of the left AV valve occurs near the beginning of __________.
ventricular systole
The majority of ventricular filling occurs while the ventricles and atria are in what state(s)?
ventricular and atrial diastole
Which of the following most correctly describes end-diastolic volume?
the volume of the ventricle when it is most full
Left ventricular filling occurs __________.
while the AV valve is open
Heart valves are in what state during isovolumetric contraction?
The AV valves and semilunar valves are closed.
The decrease in left ventricular pressure at the end of ventricular systole causes __________.
the semilunar valve to close
Ventricular diastole begins with the closing of the semilunar valves. What phase of the cardiac cycle happens between this event and the later opening of the AV valves?
isovolumetric relaxation
The contraction phase of the cardiac cycle is called ________.
systole
Compared to the right ventricle, which of these statements about the left ventricle is false?
it ejects more blood
The first heart sound is heard when the
AV valves close.
During the cardiac cycle, the
both QRS complex of the ECG precedes the increase in ventricular pressure and first heart sound coincides with the QRS complex of the ECG.
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves.
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.
Pressure in the atria would be greater than the pressure in the ventricles.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Increased pressure in the ventricles would close what valve(s)?
AV valves only
________ are abnormal heart sounds caused by turbulent flow through faulty valves.
murmurs
The backward flow of blood from a ventricle to its atrium or from a outflow vessel to its ventricle is called ________.
regurgitation
Which of the following would increase heart rate?
decreased parasympathetic stimulation of nodal fibers
increased levels of epinephrine
increased sympathetic stimulation of SA node
faster depolarization of the pacemaker potential
Each of the following factors will increase cardiac output, except
increased parasympathetic stimulation.
Cardiac output is increased by
more sympathetic stimulation and increased stroke volume.
The cardiac ________ is the difference between the resting and maximal cardiac output.
reserve
Drugs that block the beta-one adrenergic receptors will
decrease HR
If a patient's tricuspid valve was leaking during systole, what would happen?
regurgitation into the right atrium
The amount of blood returning to the heart is the ________.
venous return
The ________ is the volume of blood in a ventricle at the beginning of systole.
end-diastolic volume
The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the
systolic ejection phase.
The first heart sound ("lub")
is associated with closing of the mitral valve.
Pacemaker cells isolated from the SA node generate action potentials at ________ beats per minute.
80-100
During ventricular systole, the
AV valves are closed
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume
Which of the following would increase heart rate?
epinephrine and norepinephrine
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
The heart is innervated by ________ nerves.
both parasympathetic and sympathetic
The volume of blood ejected from each ventricle during a contraction is called the
stroke volume
Drugs known as calcium channel blockers such as nifedipine can be used to
decrease blood pressure.
decrease the force of cardiac contraction.
produce a negative inotropic effect.
dilate the coronary arteries.
Stroke volume depends on
end diastolic volume, the contractility of the ventricle, and the pressure required to pump blood into the aorta.
Heart rate is controlled by neurons of the cardiovascular center located in the
medulla oblongata.
Which of these would cause stroke volume to increase?
both when venous return is increased and when diastolic blood pressure is decreased
In mitral valve prolapse, the cusps of the mitral valve are pushed into the ________ atrium.
left
Cardiac output can be increased by all of the following except one. Choose the exception.
decreasing ejection fraction
"An increase in end-diastolic volume increases the stroke volume" is a way of stating
Starling's law of the heart.
Which of these is not needed to determine cardiac output?
blood pressure
Acetylcholine slows the heart because it
opens potassium ion channels in SA node cells and causes the pacemaker potential to depolarize more slowly.
Which of these is true about the atrial reflex?
depends on sympathetic innervation
triggered by atrial mechanoreceptors
also called Bainbridge reflex
triggered by increasing venous return
Pacemaker cells in the SA node
both show a slow spontaneous depolarization and are connected by gap junctions to atrial myocytes.
Which of the following would be greater?
the end-diastolic volume when the heart rate is 60 beats/minute (as opposed to 150 bpm)
Activation of which kind of receptor causes heart rate to increase?
beta-one receptor
The cardioacceleratory center activates sympathetic neurons and the cardioinhibitory center controls parasympathetic neurons.
Both parts of the statement are true and relate to brainstem control of heart rate.
David suffers from a prolapsed mitral valve. This condition would cause
both increased effort by the left ventricle and systolic murmur.
The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.
end-systolic volume
The principle that increasing the end-diastolic volume results in a corresponding increase in the stroke volume is known as ________.
Starling's law of the heart