Located in the Ventral Body Cavity
Ventral body cavity thoracic
pleural pericardial mediastinum
abdominopelvic abdominal pelvic
The Size of the Heart
• About same size as a closed fist• the base is the wider
superior portion• the apex is the point
Fibrous Pericardium rests on and is attached
to diaphragm a tough, inelastic sac of
fibrous connective tissue anchored to the blood
vessels entering and leaving the base of the heart
protects and anchors the heart; prevents overfilling of the chambers of the heart
Parietal (Outer) Serous Pericardium
simple squamous epithelium
forms outer parietal layer bound to fibrous pericardium
secretes a serous (watery) lubricating fluid
reduces friction as the heart contracts and twists
Visceral (Inner) Serous Pericardium
simple squamous epithelium forms the epicardium
forms visceral layer bound to the myocardium of the heart
secretes serous fluid
reduces friction as the heart pumps, contracts and twists
Heart wall - Three layers Epicardium (outer)
visceral layer of pericardium
thin, transparent smooth, slippery
Myocardium (middle) mass of cardiac muscle
Endocardium (inner) endothelium over thin
connective tissue smooth lining for the
chambers and valves continuous with blood
vessel endothelium
Myocardium (Cardiac Muscle)
Cardiac muscle cells are involuntary, striated, branched
Each fiber is connected to the others by intercalated discs gap junctions allow
action potentials to pass from fiber to fiber
desmosomes (“spot welds”) to prevent cardiac fibers from separating during contractions
Intercalated Discs[Note the striations and recall the sliding filament method of muscle contraction.]
Surface of the Heart External
landmarks Atrioventricular
grooves separate atria from ventricles
Anterior/posterior interventricular sulcus separates right and left ventricles
Coronary vessels run in these grooves