Chapter 20
Cardiac muscle tissue is characterized by all of these except :
Long, multinucleated, cylindrical cells
Bifurcated (branched) cells
Intercalated discs
Numerous large mitochondria
Striations
The autorhythmic cells of the heart
Constitute approximately 90% of the cardiac myofibers
Depolarize to threshold spontaneously
Depolarize more slowly than other cardiac myofibers
Are found in the fibrous skeleton of the heart
Depolarize only in response to neurotransmitters or hormones
The primary pacemaker of the heart is the
Purkinje fiber
AV bundle (bundle of His)
Right bundle branch
SA node
Left bundle branch
Place the following in order of the propagation of a cardiac action potential: 1. Purkinje fibers 2. SA node 3. Right and left bundle branches 4. AV bundle 5. AV node
2, 4, 5, 3, 1
5, 2, 4, 1, 3
5, 2, 4, 3, 1
2, 4, 3, 1, 4
2, 5, 4, 3, 1
All of the following are true of the cardiac conduction system except:
The av node can take over the pacemaker task if the SA node is damaged
Autonomic system impulses establish the fundamental rhythm of the heart
The peacemaking ability of the AV bundle alone is not sufficient to maintain homeostasis
Ectopic pacemakers may be stimulated be caffeine or nicotine
Ach release by the parasympathetic division of the ANS decreases SA node depolarization
The refractory period of cardiac muscle fibers
Is a time interval during which another contraction is initiated
Is much shorter than their contraction period
Prevents tetany and allows the heart to act as a pump
A and b are correct
A, b, and c are correct
In cardiac muscle,
Most of the ATP production is anaerobic
Most of the ATP used while at rest comes from oxidation of fatty acids
No ATP is produced from creatine phosphate
O2 is actively transported across the sarcolemma
Lactic acid production decreases during exercise
Which of the following does an electrocardiogram detect?
Cardiomegaly (enlargement of the heart)
Ischemic coronary blood vessels
Disturbances of the conduction pathway of the heart
Damage to certain regions of the heart
All of these may be detected by an ECG
The QRS complex of the ECG is associated with
Atrial depolarization
Ventricular depolarization
Atrial repolarization
Ventricular repolarization
A and b are correct
A patient's ECG contains a prolonged P-Q interval, but is otherwise unremarkable. Which of the following is true of this patient's condition?
The patient is having an acute myocardial infraction
The patient probably has hyperkalemia
The patient probably has ventricular hypertrophy
The patient may have coronary artery disease
The patient probably has atrial atrophy
Which of the following correlations between cardiac contractions and ECG waves is correct?
Atrial systole persists through the S-T segment
All chambers are contracted during the period between the T wave and the next P wave
Ventricular systole begins after the QRS complex appears
Atrial diastole precedes the appearance of the QRS complex
Ventricular diastole precedes the appearance of the T wave
A single cardiac cycle
Lasts 8 sec when the heart rate is 75 beats/minute
Forces blood from areas of lower pressure to areas of higher pressure
Occurs independently of electrical activity in the heart
Includes all of the events associated with one heart beat
Refers only to ventricular events
Which event occurs during ventricular systole?
Depolarization of the SA node
Filing of the atria
Ventricular pressure drops
Opening of the AV valves
Isovolumetric contraction
Which of the following describe the relaxation period of the cardiac cycle?
It is a time when the atria are contracted
It is a time that becomes shorter as the heart rate increases
It is a time when the AV valves are closed
It is the time when the ventricles receive most of the blood from the aorta
It is a time when the SL valves are open
The amount of blood contained in a ventricle at the end of atrial systole is the
Stroke volume
Ejection fraction
End-diastolic volume
End-systolic volume
Cardiac output
The heart
Lies just inferior to the diaphragm
Lies lateral to the lungs
Lies within the mediastinum
Lies anterior to the sternum
All of the above
The pericardium
Anchors the heart to the diaphragm
Includes a serous outer layer
Includes a fibrous inner layer that is also called the epicardium
Secretes a mucoid film that reduces friction between the heart and the chest wall
Contains fluid between the fibrous and parietal serous layers
The heart wall
Is composed of five layers of voluntary muscle arranged in diagonal, swirling bands
Includes the endocardium, or outermost layer, which is contiguous with the serous pericardium
Has an inner layer called the epicardium, which is fused with the fibrous layer of the pericardium
Consists largely of a middle layer of muscular tissue called the myocardium which preforms the pumping action of the heart
All of these are correct
Which of the following is normally observed on the external surface of the heart?
An auricle on the anterior of each ventricle
A series of sulci that contain coronary blood vessels and a variable amount of fat
A shallow coronary sulcus that encircles most of the heart marking the boundary between the inferior atria and superior ventricles
A shallow groove called the anterior intreventricular sulcus on the anterior surface marking the boundary between the right and left ventricles
A right ventricle which is much larger the left ventricle
Which of the following are normally observed in the right atrium after birth?
Opening from the coronary sinus, superior vena cava and inferior vena cava
Pectinate muscles on the posterior wall
A foramen on the medial surface leading into the left atrium
A semilunar valve leading into the right ventricle
Openings form the pulmonary veins
Which of the following are normally observed in the left ventricle after birth?
A tricuspid valve allowing blood to enter from the left atrium
A semilunar valve allowing blood to exit to the pulmonary trunk
An incomplete ventricular septum
Papillary muscle and chordae tendinae attached to the semilunar valve
Raised bundles of cardiac muscle fibers called trabeculae carneae
Which of the following is true of the left ventricle?
The left and right ventricles contrast asynchronously
The left ventricle has a lumen with a circular perimeter
The left ventricle pumps blood against less resistance than the right ventricle
The left ventricle pumps blood a shorter distance than the right ventricle
The left ventricle has a thinner wall than the right ventricle
Each of the cardiac valves
Opens and closes in response to changes in pressure
Attaches to the ventricular walls via chordae tendinae
Ensures one-way blood flow through the heart
A and c are correct
All of the are correct
A medical student examines a valve that has been removed from a heart. He observes that the valve has 3 crescent moon shaped cusps, but no chordae tendinae. What conclusion could he draw based on those observations?
The valve is the tricuspid valve
The valve is the bicuspid valve
The valve is the pulmonary semilunar valve
The valve is the aortic semilunar valve
The valve could be either the aortic or the pulmonary semilunar valve
Why doesn't a significant amount of blood flow back into the vena cavae and the coronary sinus during atrial contraction?
The semilunar valves block the venous openings
The tricuspid valve blocks the venous openings
The contraction of the atria compresses and closes the venous openings
The bicuspid valve blocks the venous openings
The venous valves block the venous openings
Which of the following represents the correct sequence of parts through which blood flows as it moves lower body to the to the left atrium? 1. Pulmonary veins 2. Superior vena cava 3. Right ventricle 4. Pulmonary valve 5. Pulmonary trunk and arteries 6. Inferior vena cava 7. Tricuspid valve 8. Right atrium 9. lungs
1, 9, 5, 4, 3, 7, 8, 6, but never 2
2, 8, 7, 3, 4, 5, 9, 1, but never 6
1, 9, 5, 4, 3, 7, 8, 2, but never 6
6, 8, 7, 3, 4, 5, 9, 1, but never 2
6, 3, 7, 8, 4, 5, 9, 1, but never 2
Blood passing through the bicuspid valve will enter the
Left atrium
Left ventricle
Right atrium
Right ventricle
Aorta
Blood in the coronary sinus will drain into the
Left atrium
Left ventricle
Right atrium
Right ventricle
Aorta
All of the following statements about circulation of blood are true except:
The systemic circulation circuit receives blood from the left ventricle
The pulmonary circulation transports blood from the heart to the lungs and back to the heart
The first blood vessel in the systemic circuit is the aorta
The coronary circulation is part of the pulmonary circuit
The right side of the heart is the pump for the pulmonary circuit
Which of the following does not supply the heart with nutrient and oxygen rich blood?
Anterior interventricular branch
Circumflex artery
Great cardiac vein
Posterior interventricular branch
Right marginal branch
During the cardiac cycle, there is an interval during which cardiac fibers are contracting but not shortening. The intraventricular pressure decreases, but the ventricular volume remains the same. What is this interval called?
Atraial systole
Atrial diastole
Ventricular diastole
Isovolumetric relaxation
Isovolumetric contraction
Heart sounds
May be detected by an ECG
Are the results of the cardiac valves closing
Are the results of the cardiac valves opening
Are associated with smoothly flowing blood
Are best assessed on the posterior thoracic wall
Cardiac output
Is the volume of blood ejected from the left ventricle into the aorta
Is the volume of blood ejected from the right ventricle into the pulmonary trunk
Is the product of the stroke volume and the heart rate
A and b are correct
A, b, and c are correct
A patient has an EDV of 90 mL and an ESV of 40 mL with a heat rate of 50. What is this patient's cardiac output?
6500 mL/min or 6.5 L/min
2000 mL/min or 2.0 L/min
4500 mL/min or 4.5 L/min
2500 mL/min or 2.5 L/min
180 mL/min or 0.18 L/min
A patients maximum cardiac output is 20 L/min. Her resting cardiac output is 5 L/min. What is the patient's cardiac reserve?
15 L/min
100 L/min
4 L/min
50 L/min
25 L/min
Which of the following correctly describes how stroke volume regulated?
By adjusting the preload, the pressure that must be overcome to open an SL valve
By adjusting the contractility, or strenth of contraction of the heart at a given preload
By adjusting the afterload, or degree of stretch on the heart before it contracts
A and b are correct
A, b, and c are correct
The Frank-Starling law of the heart states that
That increased filling time will decrease the force of contraction by the ventricles
The right and left ventricles must pump equal amounts of blood with each heart beat
A healthy heart will pump out all the blood that entered during the previous diastole
The greater the preload on cardiac muscle fibers, the weaker the force of contraction will be
The greater the preload on cardiac muscle fibers, the greater the force of contraction will be
A patient has pulmonary edema but not peripheral edema. Which of the following is probably true of the patients heart?
The patients left ventricle is failing
The patients left atrium is failing
The patients right ventricle is failing
The patients right atrium is failing
The patients heart is working normally
Which of the following is not true of regulation of heart rate?
Nervous system is originates in the cardiovascular center of the medulla oblongata
Sympathetic impulses travel to the heart primarily along the vagus (X) nerves
The limbic system can influence the cardiovascular center of the medulla oblongata
Proprio-, chemo-, and baroreceptors detect changes and influence the cardiovascular center
Increased stimulation by the cardiac accelerator nerve increases heart rate
Which of the following would be expected to slow heart rate and decreases cardiac output?
Epinephrine
Norepinephrine
Ach
Hyponatremia
T3/T4
Which of the following statements is true of heart rate?
Newborns typically have heart rates of 50 beats/minute or less
Men typically have slightly faster heart rates than women
Athletes typically have faster heart rates than sedentary individuals
Hyperthermia decreases heart rate
Regular exercise tends to reduce resting heart rate in both male and females
What is the relationship between exercise and the heart?
A person's cardiovascular fitness can be improved with regular exercise
Aerobic exercise decreases cardiac output and should be limited to twice a week
A healthy person's cardiovascular fitness declines after several weeks of training
Regular exercise causes loss of cardiac muscle tissue
During strenuous activity, a sedentary person's cardiac output is greater than an athlete's
All of the following are risk factors for coronary artery disease (CAD) except:
Hyperlipidemia
Obesity
Type "A" personality
Smoking
Regular aerobic exercise
A myocardial infarction
Results from an interrupted blood supply to part of the heart
Causes death of part of the heart
Is usually treated with pro-coagulation therapy
A and b are correct
A, b, and c are correct
Middle of the heart wall, muscle layer
Endocardium
Epicardium
Fibrous pericardium
Mediastinum
Myocardium
Also known as the visceral layer of the serous pericardium
Endocardium
Epicardium
Fibrous pericardium
Mediastinum
Myocardium
Remnant of fetal opening between right and left atria
Auricles
Carneae trabeculae
Fossa ovalis
Pactinate muscles
Septum
Increase capacity of blood atria can hold
Auricles
Carneae trabeculae
Fossa ovalis
Pactinate muscles
Septum
Found in atria, help push blood into ventricles
Auricles
Carneae trabeculae
Fossa ovalis
Pactinate muscles
Septum
Help papillary muscles hold AV valves shut while ventricles contract
Aortic semilunar valve
Bicuspid valve
Chordae tendinae
Pulmonary SL valve
Tricuspid valve
Involved in mitral valve stenosis
Aortic semilunar valve
Bicuspid valve
Chordae tendinae
Pulmonary SL valve
Tricuspid valve
Help closed during ventricular diastole by back flow of blood from pulmonary circuit
Aortic semilunar valve
Bicuspid valve
Chordae tendinae
Pulmonary SL valve
Tricuspid valve
Only site where action potentials conduct from atrium to ventricles
AV bundles (Bundle of His)
AV node
Left and right bundle branches
Purkinje fibers
SA node
Only site where action potentials conduct from atrium to ventricles
AV bundles (Bundle of His)
AV node
Left and right bundle branches
Purkinje fibers
SA node
Only site where action potentials conduct from atrium to ventricles
AV bundles (Bundle of His)
AV node
Left and right bundle branches
Purkinje fibers
SA node
Represent time when ventricular contractile fibers depolarized during plateau of action potential
P wave
P-Q interval
QRS complex
S-T segment
T wave
Represent time when ventricular contractile fibers depolarized during plateau of action potential
P wave
P-Q interval
QRS complex
S-T segment
T wave
Represent time when ventricular contractile fibers depolarized during plateau of action potential
P wave
P-Q interval
QRS complex
S-T segment
T wave
Ventricular volume after atria have emptied
Diastole
End-diastolic volume
End-systolic volume
Isovolumetric relaxation
Systole
Ventricular volume after atria have emptied
Diastole
End-diastolic volume
End-systolic volume
Isovolumetric relaxation
Systole
Time when cardiac chamber is contracting
Diastole
End-diastolic volume
End-systolic volume
Isovolumetric relaxation
Systole
Stroke volume X hear rate
Cardiac output
Factors regulating stroke volume
Factors regulating heart rate
Negative inotropic agents
Positive inotropic agents
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