Electrocardiogram (ECG or EKG)

graphic record of the electrical activity of the heart

Endocardium

endothelial membrane that lines the interior of the heart

Extrasystole

premature heart contraction

Fibrillation

condition of rapid and irregular or out-of-phase heart contractions

Heart Attack (Coronary)

condition characterized by dead tissue areas in the myocardium; caused by interruption of blood supply to the area. See Myocardial infarction

Heart Block

impaired transmission of impulses from atrium to ventricle resulting in abnormally slow heart rhythms

Heart Murmur

abnormal heart sound (usually resulting from valve problems)

Incompetent Valve

valve which does not close properly

Infarct

region of dead, deteriorating tissue resulting from a lack of blood supply

Intercalated Discs

specialized connections between myocardial cells containing gap junctions and desmosomes

Mediastinum

the medial cavity of the thorax containing the heart, great vessels, and trachea

Mitral (bicuspid) Valve (mitral)

the left atrioventricular valve

Myocardial Infarction (MI)

Condition characterized by dead tissue areas in the myocardium; caused by interruption of blood supply to the area; commonly called heart attack

Myocardium

layer of the heart wall composed of cardiac muscle

Pericardium

double-layered sac enclosing the heart and forming its superficial layer; has fibrous and serous layers

Peripheral Congestion

condition caused by failure of the right side of the heart; results in edema in the extremities

Pulmonary Circuit

system of blood vessels that serves gas exchange in the lungs; i.e., pulmonary arteries, capillaries, and veins

Semilunar Valves

valves that prevent blood return to the ventricles after contraction; aortic and pulmonary valves

Sinoatrial (SA) Node

specialized myocardial cells in the wall of the right atrium; pacemaker of the heart

Stenosis

abnormal constriction or narrowing

Stroke Volume (SV)

amount of blood pumped out of a ventricle during one contraction

Subendocardial Conducting Network

modified ventricular muscle fibers of the conduction system of the heart; also called Purkinje fibers

Superior Vena Cava

vein that returns blood from body regions superior to the diaphragm

Systemic Circuit

system of blood vessels that serves gas exchange in the body tissues

Systole

period when either the ventricles or the atria are contracting

Tachycardia

a heart rate over 100 beats per minute

Tricuspid Valve

the right atrioventricular valve

Ventricles

(1) paired, inferiorly located heart chambers that function as the major blood pumps; (2) cavities in the brain

Describe the size, shape, location, and orientation of the heart in the thorax.

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Name the coverings of the heart.

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Describe the structure and function of each of the three layers of the heart wall.

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The heart is in the mediastinum. Just what is the mediastinum?

The mediastinum is the medial cavity of the thorax within which the heart, great vessels, and trachea are found.

From inside to outside, list the layers of the heart wall and the coverings of the heart.

The layers of the heart wall are the endocardium, the myocardium, and the epicardium. The epicardium is also called the visceral layer of the serous pericardium. This is surrounded by the parietal layer of the serous pericardium and the fibrous pericardiu

What is the purpose of the serous fluid inside the pericardial cavity?

The serous fluid decreases friction caused by movements of the layers against one another.

Describe the structure and functions of the four heart chambers. Name each chamber and provide the name and general route of its associated great vessel(s).

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Name the heart valves and describe their location, function, and mechanism of operation.

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What is the function of the papillary muscles and chordae tendineae?

The papillary muscles and chordae tendinae keep the AV valve flaps from everting into the atria as the ventricles contract.

Anastamosis

a union or joining of nerves, blood vessels, or lymphatics

Angina Pectoris

severe suffocating chest pain caused by brief lack of oxygen supply to heart muscle

Aorta

major systemic artery; arises from the left ventricle of the heart

Arrhythmia

irregular heart rhythm, often caused by defects in the intrinsic conduction system

Atherosclerosis

changes in the walls of large arteries consisting of lipid deposits on the artery walls; one form of arteriosclerosis

Atria

the two superior receiving chambers of the heart

Atrioventricular (AV) Bundle

bundle of specialized fibers that conduct impulses from the AV node to the right and left ventricles; also called bundle of His

Atrioventricular (AV) Node

specialized mass of conducting cells located at the atrioventricular junction in the heart

Atrioventricular (AV) Valve

Valve that prevents backflow into the atrium when the connected ventricle is contracting

Bradycardia

a heart rate below 60 beats per minute

Cardiac Cycle

sequence of events encompassing one complete contraction and relaxation of the atria and ventricles of the heart

Cardiac Output (CO)

amount of blood pumped out of a ventricle in one minute

Cardiac Reserve

the difference between resting and maximal cardiac output

Congenital

existing at birth

Congestive Heart Failure (CHF)

condition in which the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs

Coronary Circulation

the functional blood supply of the heart; shortest circulation in the body

Diastole

period of the cardiac cycle when either the ventricles or the atria are relaxing

Trace the pathway of blood through the heart.

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Name the major branches and describe the distribution of the coronary arteries.

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Which side of the heart acts as the pulmonary pump? The systemic pump??

The right side of the heart acts as the pulmonary pump, whereas the left acts as the systemic pump.

Which of the following statements are true?
a. The left ventricle wall is thicker than the right ventricle wall.
b. The left ventricle pumps blood at a higher pressure than the right ventricle.
c. The left ventricle pumps more blood with each beat than th

(a) True, the left ventricle wall is thicker than the right.
(b) True, the left ventricle pumps blood at much higher pressure than the right ventricle because the left ventricle supplies the whole body, whereas the right ventricle supplies only the lungs.

Name the two main branches of the right coronary artery.

The branches of the right coronary artery are the right marginal artery and the posterior interventricular artery.

Describe the structural and functional properties of cardiac muscle, and explain how it differs from skeletal muscle.

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Briefly describe the events of cardiac muscle cell contraction.

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For each of the following, state whether it applies to skeletal muscle, cardiac muscle, or both:
a. refractory period is almost as long as the contraction
b. source of Ca�? for contraction is only SR
c. AP exhibits a plateau phase
d. has troponin
e. has t

(a) The refractory period is almost as long as the contraction in cardiac muscle.
(b) The source of Ca�? for the contraction is only SR in skeletal muscle.
(c) The AP exhibits a plateau phase in cardiac muscle.
(d) Both skeletal muscle and cardiac muscle

Cardiac muscle cannot go into tetany. Why?

Cardiac muscle cannot go into tetany because the absolute refractory period is almost as long as the contraction.

Name the components of the conduction system of the heart, and trace the conduction pathway.

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Name the individual waves and intervals of a normal electrocardiogram tracing, and indicate what each represents.

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Name some abnormalities that can be detected on an ECG tracing.

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Which part of the intrinsic conduction system directly excited ventricular myocardial cells? In which direction does the depolarization wave travel across the ventricles??

The subendocardial conducting network excites ventricular muscle fibers. The depolarization wave travels upward from the apex toward the atria, and from endocardium to epicardium.

Describe the electrical event in the heart that occurs during each of the following:
a. the QRS wave of the ECG
b. the T wave of the ECG
c. the P-R interval of the ECG

(a) The QRS wave of the ECG occurs during ventricular depolarization.
(b) The T wave of the ECG occurs during ventricular repolarization.
(c) The P-R interval of the ECG occurs during atrial depolarization and the conduction of the action potential throug

Describe normal heart sounds, and explain how heart murmurs differ.

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Describe the timing and events of the cardiac cycle.

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The second heart sound is associated with the closing of which valve(s)?

The second heart sound is associated with the closing of the semilunar valves.

If the mitral valve were insufficient, would you expect to hear the murmur (of blood flowing through the valve that should be closed) during ventricular systole or diastole?

The murmur of mitral insufficiency occurs during ventricular systole (because this is when the valve should be closed, and the murmur is due to blood leaking the incompletely closed valve into the atrium).

During the cardiac cycle, there are two periods when all four valves are closed. Name these two periods.

The periods when all four valves are closed are the isovolumetric contraction phase and the isovolumetric relaxation phase.

Name and explain the effects of various factors regulating stroke volume and heart rate.

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Explain the role of the autonomic nervous system in regulating cardiac output.

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After running to catch a bus, Josh noticed that his heart was beating faster than normally and was pounding forcefully in his chest. How did his increased HR and SV come about?

Exercise activates the sympathetic nervous system. Sympathetic nervous system activity increases heart rate. It also directly increases ventricular contractility, thereby increasing Josh's stroke volume.

What problem of cardiac output might ensue if the heart beats far too rapidly for an extended period, that is, if tachycardia occurs? Why??

If the heart is beating very rapidly, the amount of time for ventricular filling between contractions is decreased. This decrease and end diastolic volume, decreases the stroke volume, and therefore decreases the cardiac output.

Describe the development of the heart, and indicate how the fetal heart differs from the adult heart.

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Provide examples of age-related changes in heart function.

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Name the two components of the fetal heart that allows blood to bypass the lungs.

The foramen ovale and the ductus arteriosus both allow blood to bypass the fetal lungs.

In the past decade, many people over 70 have competed in the Ironman World Championships in Hawaii. In what way night age-related changes of the heart limit the performance of these athletes?

Elderly athletes may be hampered by sclerosis and thickening of heart valve flaps, a decline in cardiac reserve, fibrosis of cardiac muscle, and artherosclerosis.