16 terms

USI Summer Session Chapter 18 A&P - The Heart

The Heart
size of a fist

In the mediastinum between second rib and fifth intercostal space
On the superior surface of diaphragm
Two-thirds to the left of the midsternal line
Anterior to the vertebral column, posterior to the sternum
Enclosed in pericardium, a double-walled sac
Protects, anchors, and prevents overfilling
Deep two-layered serous pericardium
Parietal layer lines the internal surface of the fibrous pericardium
Visceral layer (epicardium) on external surface of the heart
Separated by fluid-filled pericardial cavity (decreases friction)
visceral layer of the serous pericardium
Spiral bundles of cardiac muscle cells

Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

Anchors cardiac muscle fibers
•Supports great vessels and valves
•Limits spread of action potentials to specific paths
continuous with endothelial lining of blood vessels
Separated internally by the interatrial septum

Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles

Auricles increase atrial volume
Separated by the interventricular septum

Anterior and posterior interventricular sulci mark the position of the septum externally
Atria: The Receiving Chambers
Walls are ridged by pectinate muscles

Vessels entering right atrium

Superior vena cava

Inferior vena cava

Coronary sinus

Vessels entering left atrium

Right and left pulmonary veins
Ventricles: The Discharging Chambers
Walls are ridged by trabeculae carneae

Papillary muscles project into the ventricular cavities
Coronary Circulation
The functional blood supply to the heart muscle itself

Arterial supply varies considerably and contains many anastomoses (junctions) among branches

Collateral routes provide additional routes for blood delivery
Coronary Circulation: Arteries
Right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries
Coronary Circulation: Veins
Small cardiac, middle, and great cardiac veins

Coronary sinus
Homeostatic Imbalances
Angina pectoris

Myocardial infarction (heart attack)
Angina pectoris
Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium
Myocardial infarction
(heart attack)

Prolonged coronary blockage

Areas of cell death are repaired with noncontractile scar tissue