1. Gross Anatomy of Heart
By : Dr. Prenika Shangloo
Demonstrator Anatomy
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Heart Anatomy
• Approximately the size of your fist
• Location
• Superior surface of diaphragm
• Left of the midline
• Anterior to the vertebral column, posterior to the
sternum
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Heart Wall
• Epicardium – visceral layer of the serous
pericardium
• Myocardium – cardiac muscle layer forming the bulk
of the heart
• Fibrous skeleton of the heart – crisscrossing,
interlacing layer of connective tissue
• Endocardium – endothelial layer of the inner
myocardial surface
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• Returning blood to the heart
• Superior and inferior venae cavae
• Right and left pulmonary veins
• Conveying blood away from the heart
• Pulmonary trunk, which splits into right and left
pulmonary arteries
• Ascending aorta (three branches) – brachiocephalic,
left common carotid, and subclavian arteries
External Heart: Major Vessels of the Heart
(Anterior View)
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• Arteries – right and left coronary (in atrioventricular
groove), marginal, circumflex, and anterior
interventricular
• Veins – small cardiac vein, anterior cardiac vein, and
great cardiac vein
External Heart: Vessels that Supply/Drain the
Heart (Anterior View)
16. External features of heart
• Apex: directed downwards and towards left.
• Base (posterior srpace): directed backwards
• Borders: upper, inferior, right and left borders.
• 3 surfaces: anterior or sternocostal surface, inferior or
diaphragmatic surface and left lateral surface
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• Returning blood to the heart
• Right and left pulmonary veins
• Superior and inferior venae cavae
• Conveying blood away from the heart
• Aorta
• Right and left pulmonary arteries
External Heart: Major Vessels of the Heart
(Posterior View)
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• Arteries – right coronary artery (in atrioventricular
groove) and the posterior interventricular artery (in
interventricular groove)
• Veins – great cardiac vein, posterior vein to left
ventricle, coronary sinus, and middle cardiac vein
External Heart: Vessels that Supply/Drain the
Heart (Posterior View)
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Atria of the Heart
• Atria are the receiving chambers of the heart
• Each atrium has a protruding auricle
• Pectinate muscles mark atrial walls
• Blood enters right atria from superior and inferior
venae cavae and coronary sinus
• Blood enters left atria from pulmonary veins
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Ventricles of the Heart
• Ventricles are the discharging chambers of the heart
• Papillary muscles and trabeculae carneae muscles
mark ventricular walls
• Right ventricle pumps blood into the pulmonary trunk
• Left ventricle pumps blood into the aorta
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Heart Valves
• Heart valves insure unidirectional blood flow through the
heart
• Atrioventricular (AV) valves lie between the atria and the
ventricles
• Also called the Tricuspid and Bicuspid (Mitral) valves
• AV valves prevent backflow into the atria when ventricles
contract
• Chordae tendineae anchor AV valves to papillary muscles
• Papillary muscles pre-tense the chordae prior to
ventricular contraction
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Heart Valves
• Aortic semilunar valve lies between the left ventricle
and the aorta
• Pulmonary semilunar valve lies between the right
ventricle and pulmonary trunk
• Semilunar valves prevent backflow of blood into the
ventricles
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Microscopic Heart Muscle Anatomy
• Cardiac muscle is striated, short, fat, branched, and
interconnected
• Connective tissue endomysium acts as both tendon
and insertion
• Intercalated discs anchor cardiac cells together and
allow free passage of ions
• Heart muscle behaves as a functional syncytium
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Cardiac Muscle Contraction
• Heart muscle:
• Is stimulated by nerves and self-excitable (automaticity
or autorhythmicity)
• Contracts as a unit (functional syncytium)
• Has a long (250 ms) absolute refractory period
compared to skeletal’s (~ 5ms)
• Cardiac muscle contraction is similar to skeletal muscle
contraction (sliding filament theory)
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• Autorhythmic
• Myocardial Characteristics:
• Intercalated discs
• Desmosomes
• Gap Junctions
• Fast signals
• Cell to cell
• Many mitochondria
• Large T tubes
Cardiac Muscle Cells:
Figure 14-10: Cardiac muscle
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Cardiopathologies
• Myocardial Infarction
• Ischemia (holding back blood) is due to a stenosis
caused by atheroschlosis. The pain, angina pectoris
is usually an indicator of a TIA (transient ischemic
attack)
• Necrosis (death) of myocardium due to ischemia
associated w/ the stenosis.
• Myocardia is amitotic and therefore will not repair
itself. Scar tissue instead.
• Seriousness depends on location/extent
• Treatment would include dealing w/ stenosis,
vasodilators, beta-blockers (reduce blood pressure),
heart transplant, LVAD.
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Alterations in Blood Pressure
• Hypotension – low BP in which systolic pressure is
below 100 mm Hg
• Hypertension – condition of sustained elevated
arterial pressure of 140/90 or higher
• Transient elevations are normal and can be caused by
fever, physical exertion, and emotional upset
• Chronic elevation is a major cause of heart failure,
vascular disease, renal failure, and stroke
(cerebrovascular accident)
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Hypotension
• Orthostatic hypotension – temporary low BP and
dizziness when suddenly rising from a sitting or
reclining position
• Chronic hypotension – hint of poor nutrition and
warning sign for Addison’s disease
• Acute hypotension – important sign of circulatory
shock
• Threat to patients undergoing surgery and those in
intensive care units
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Hypertension
• Primary or essential hypertension – risk factors in
primary hypertension include diet, obesity, age, race,
heredity, stress, and smoking
• Secondary hypertension – due to identifiable
disorders, including excessive renin secretion,
arteriosclerosis, and endocrine disorders
