Anatomy of the Heart

Location of the Heart

Position of the heart and associated structures in the mediastinum. The positions of the heart and associated structures in the mediastinum are indicated by dashed outlines

Pericardium

• The membrane that surrounds and protects the heart is the pericardium(per-i-KAR-de¯-um; peri- around)• The pericardium consists of two main parts: (1) the fibrous pericardium

and (2) the serous pericardium• The superficial fibrous pericardiumis composed of tough, inelastic,

dense irregular connective tissue• The deeper serous pericardiumis a thinner, more delicate membrane

that forms a double layer around the heart• The outer parietal layer of the serous pericardiumis fused to the • fibrous pericardium.

• The inner visceral layer of the serous pericardium, which is also called the epicardium is one of the layers of the heart wall and adheres tightly to the surface of the hear• Between the parietal and visceral layers of the serous pericardium is a

thin film of lubricating serous fluid. This slippery secretion of the pericardial cells, known as pericardial fluid, reduces friction between the layers of the serous pericardium as the heart moves. The space that contains the few milliliters of pericardial fluid is called the pericardial cavity.

Pericardium and heart wall.

Layers of the Heart Wall

• The epicardiumis composed of two tissue layers. The outermost, as you just learned, is called the visceral layer of the serous pericardium.This thin, transparent outer layer of the heart wall is composed of mesothelium. Beneath the mesothelium is a variable layer of delicate fibroelastic tissue and adipose tissue• The middle myocardium(mı¯-o¯-KAR-de¯-um; myo- muscle) is responsible for

the pumping action of the heart and is composed of cardiac muscle tissue• The innermost endocardium(en-do¯-KAR-de¯-um; endo- within) is a thin

layer of endothelium overlying a thin layer of connective tissue. It provides a smooth lining for the chambers of the heart and covers the valves of the heart

Chambers of the Heart

Heart Valves and Circulation of Blood

Systemic and Pulmonary Circulations

Coronary Circulation

Histology of Cardiac Muscle Tissue

Action Potential and Contraction of Contractile Fibers

ATP Production in Cardiac Muscle

Heart Sounds

Cardiac Output