The inner lining of the heart.
Endocardium
Heart muscle.
Myocardium
Serous layer covering the heart muscle
Epicardium
The outermost layer of the serous pericardium
Parietal layer
The pacemaker of the heart.
SA node
Found in the interventricular septum.
AV bundle
Network found in the ventricular myocardium.
Mitral valve
The point in the conduction system of the heart where the impulse is temporarily delayed
Tricuspid valve
Prevents backflow into the left ventricle
AV bundle
Prevents backflow into the right atrium
...
Prevents backflow into the left atrium.
...
Prevents backflow into the right ventricle
...
The myocardium receives its blood supply from the coronary arteries.
true
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle.
false
Proper function of the heart is dependent upon blood levels of ionic sodium
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.
true
Tissues damaged by myocardial infarction are replaced by connective tissue.
true
The left side of the heart pumps the same volume of blood as the right.
true
Chronic release of excess thyroxine can cause a sustained increase in heart rate and a weakened heart
true
The mitral valve has chordae but the tricuspid valve does not.
false
Trabeculae carneae are found in the ventricles and never the atria.
true
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.
false
Autonomic regulation of heart rate is via two reflex centers found in the pons.
false
The dicrotic notch refers to the brief rise in pressure caused by the closure of the AV valves during ventricular systole.
false
An ECG provides direct information about valve function
false
As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve
true
Proxysmal atrial tachycardia is characterized by bursts of atrial contractions with little pause between them.
true
Normal heart sounds are caused by which of the following events?
closure of the heart valves
The enlarged coronary vessel outside the heart that empties blood into the right atrium is the ________.
coronary sinus
In the fetal heart there is a foramen ________ that allows blood to flow from the right atrium directly to the left atrium.
ovale
The ________ cells of the heart do not maintain stable resting membrane potentials; therefore, they continually depolarize.
autorhythmic
Specialized conductive cells of the ventricles are called ________ fibers.
Purkinje
The ECG T wave interval represents ________.
ventricular repolarization
CO = ________ � SV.
HR or heart rate
The ________ membrane covers the heart.
visceral layer of the serous pericardium
The ________ valve of the heart has three valves with chordae tendineae.
tricuspid
The ________ and ________ valves of the heart have no chordae tendineae attached.
aortic; pulmonary
Define systole and diastole. Which heart chambers are usually referenced when these terms are used?
Systole is contraction of the muscle. Diastole is relaxation of the muscle. The contraction and relaxation of the ventricles are normally described with the terms systole and diastole
Define the terms end diastolic volume (EDV) and end systolic volume (ESV) and relate them to the calculation of stroke volume.
EDV is the amount of blood that collects in a ventricle during diastole. ESV is the volume of blood remaining in a ventricle after it has contracted. Stroke volume (ml/beat) equals EDV - ESV.
What two important functions does the cardiac conduction system perform?
The important functions of the cardiac conduction system are to initiate impulses (pacemaker) and to distribute impulses throughout the heart so that it depolarizes and contracts in an orderly, sequential manner.
Explain autorhythmicity in cardiac muscle cells.
Autorhythmic cells do not maintain a stable resting membrane potential. Instead, they have an unstable resting potential that continuously depolarizes, drifting toward threshold for firing.
Why is oxygen so much more critical to the heart muscle than to skeletal muscles?
Cardiac muscle cells are highly dependent on oxygen and aerobic respiration. They cannot incur much oxygen debt. When forced to switch to anaerobic respiration, lactic acid and rising H+ levels impair heart function
What is the functional importance of the intercalated discs of cardiac muscle? What is the functional importance of the fibrous skeleton of the heart?
Intercalated disks contain anchoring desmosomes that prevent cell separation, and gap junctions that allow ions to travel from cell to cell. The fibrous skeleton is connective tissue that reinforces the myocardium internally.
What is bradycardia?
Bradycardia is simply slowing the heart rate below 60 beats per minute.
Why is fibrosis of the cardiac muscle serious?
As the heart muscle stiffens it is unable to fill the atria as it once did, therefore less blood is pumped. Further, as the muscle stiffens it takes more energy to expel the bolus of blood from the heart which will eventually weaken the heart.
Would an ECG with an inverted QRS wave be of concern to the doctor?
Not normally. What has probably happened is the technician has reversed the polarity on the leads causing the inverted wave.
Cardiac reserve ________.
can be improved by regular exercise
Hemorrhage with a large loss of blood causes ________.
a lowering of blood pressure due to change in cardiac output
The left ventricular wall of the heart is thicker than the right wall in order to ________.
pump blood with greater pressure
Damage to the ________ is referred to as heart block
AV node
The P wave of a normal electrocardiogram indicates ________.
atrial depolarization
Blood within the pulmonary veins returns to the ________.
left atrium
Small muscle masses attached to the chordae tendineae are the ________.
papillary muscles
The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is ________.
angina pectoris
To auscultate the aortic valve, you would place your stethoscope ________.
in the second intercostal space to the right of the sternum
The source of blood carried to capillaries in the myocardium would be the ________.
coronary arteries
When the heart is beating at a rate of 75 times per minute, the duration of one cardiac cycle is ________ second(s).
0.8
Which of the following factors does not influence heart rate?
skin color
Which of the following is not an age-related change affecting the heart?
thinning of the valve flaps
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
decreased delivery of oxygen
Cardiac muscle cells are like skeletal muscle cells in that they ________.
have I and A bands
Cardiac output is about ________ L/min.
5.25
The pericardial cavity ________.
contains a lubricating fluid called serous fluid
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells ________.
tetanic contractions might occur, which would stop the heart's pumping action
Norepinephrine acts on the heart by ________.
causing threshold to be reached more quickly
If the vagal nerves to the heart were cut, the result would be that ________.
the heart rate would increase by about 25 beats per minute
Foramen ovale ________.
connects the two atria in the fetal heart
The stroke volume for a normal resting heart is ________ ml/beat
70
Which vessel of the heart receives blood during right ventricular systole?
pulmonary trunk
Blood ejected from the ventricles enters which of these vessels during ventricular systole
both the aorta and pulmonary trunk
Which of the following is not part of the conduction system of the heart?
AV valve
The tricuspid valve is closed ________.
when the ventricle is in systole
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________.
noticing the thickness of the ventricle walls
Select the correct statement about the heart valves.
The AV valves are supported by chordae tendineae so that they do not blow back up into the atria during ventricular contraction.
Select the correct statement about the function of myocardial cells.
The all-or-none law as applied to cardiac muscle means that the entire heart contracts as a unit or it does not contract at all.
Select the correct statement about the structure of the heart wall.
The myocardium is the layer of the heart that actually contracts.
Compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
Cardiac muscle ________.
has sarcomeres with A bands and I bands
The deflection waves in an ECG tracing include ________.
the T wave, which indicates ventricular repolarization
During the period of ventricular filling ________.
blood flows passively through the atria and the open AV valves
The effect of endurance-type athletic training may be to lower the resting heart rate. This phenomenon ________.
is caused by hypertrophy of the heart muscle
The second heart sound is heard during which phase of the cardiac cycle?
isovolumetric relaxation
The time of day most hazardous for heart attacks is ________.
morning
If a significant amount of connective tissue were to develop connecting the visceral and parietal pericardial layers together, which of the following would be a likely consequence?
interference with normal mechanical cardiac activity
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
threshold is reached more quickly and heart rate would increase
Select the correct statement about cardiac output.
A slow heart rate increases end diastolic volume, stroke volume, and force of contraction
During contraction of heart muscle cells ________.
some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
Isovolumetric contraction ________.
refers to the short period during ventricular systole when the ventricles are completely closed chambers
Commotio cordis is heart failure due to a ________.
relatively mild blow to the chest
Negative chronotropic factors are factors that ________.
decrease heart rate
A 14-year-old girl undergoing a physical examination prior to being admitted to summer camp was found to have a loud heart diastolic murmur at the second intercostal space to the left side of the sternum. Explain the reason for the loud heart murmur assoc
The heart murmur is due to incomplete closing of the pulmonary valve.
A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him tha
His symptoms indicate angina pectoris, possibly due to either atherosclerosis or stress-induced spasms of the coronary arteries. If the arteries are occluded (atherosclerosis), the heart muscle could be deprived of blood, and therefore oxygen. A heart att
An angiocardiogram was performed on an infant and it was found that he had a patent ductus arteriosus. Discuss the location and function of the ductus arteriosus in the fetus and relate it to the reason for the boy's breathlessness.
The ductus arteriosus is a shunt between the pulmonary trunk and the aorta in the fetus, which normally closes at birth. Pathology is due to the mixing of oxygenated and deoxygenated blood because the connection between the aorta and the pulmonary trunk r
A patient takes a nitroglycerin tablet sublingual for chest pain. Nitroglycerin acts directly on smooth muscle, producing relaxation and vessel dilation. How would this relieve chest pain?
Angina pectoris is thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium, with resulting decreased oxygen being delivered to the cells. Because nitroglycerin acts as a vasodilator, blood flow is increased, promoting the deliver
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 - 130/80. Explain w
Increased heart rate (measured by taking his pulse) without maintaining his normal blood pressure is suggestive of reduced stroke volume. Both a drop in blood volume and a weakened heart could cause this, but the chest pains suggest heart damage. Failure
A 55-year-old male was admitted to the hospital with heart failure. He complains of increasing shortness of breath on exertion and needing to sleep on three pillows at night. On physical assessment, the nurse determines that his ankles and feet are very s
Because the heart is a double pump, each side can initially fail independently of the other. If the left side fails, pulmonary congestion occurs. The right side of the heart continues to propel blood to the lungs, but the left side does not adequately eje
Asystole is the total absence of ventricular electrical activity. Explain why defibrillation would not be effective in this situation.
) Defibrillation is accomplished by electrically shocking the heart which interrupts its chaotic twitching by depolarizing the entire myocardium. In this case, the ventricles are at a total standstill and defibrillation would not be effective.
A patient is prescribed a calcium channel blocker to prevent angina (chest pain), by decreasing the demand for oxygen. Explain why.
By preventing the influx of calcium ions into myocardial and vascular smooth muscle cells, calcium channel blockers inhibit the intracellular release of additional stores of calcium ions. A drug that inhibits the release of intracellular calcium ions decr