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LAYERS OF THE HEART

Myocardium: This is the muscular tissue of the heart and the thickest layer of the heart .

Endocardium: A thin layer of tissue that lines the heart’s chamber’s and valves.

Pericardium: A connective tissue layer around the heart and the outermost layer of the heart.

http://www.youtube.com/watch?v=wXDB__v_DVc

CARDIAC MUSCLE

• A type of involuntary striated muscle found in the walls and foundation of the heart.

• One of the three major types of muscle

• The cells that make up cardiac muscle are called cardiomyocytes.

• Contractions of these cells propel blood out of the atria and ventricles to the rest of the body.

• Rely on the coronary arteries for an ample blood supply to deliver Oxygen and remove Carbon Dioxide.

PAPILLARY MUSCLES

• Cone shaped projection on the inner surface of the ventricle.

• The contraction of these muscles tenses the chordae tendinea.

• It limits the movement of the cusps and prevents the backflow of blood into the giant atrium.

CHORDAE TENDINAE

• Fibrous chords that stabilize the position of the AV valves in the heart, preventing backflow during ventricular systole

• Connect the papillary muscles to the tricuspid valve.

CARDIAC ACTION POTENTIAL

• Action Potential means a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory.

• Differs in different portions of the heart.

• In contrast to skeletal muscle, cardiac muscle requires extracellular calcium ions for contraction to occur.

• Like skeletal muscle, the initiation and upshoot of the action potential in ventricular muscle cells is derived from the entry of sodium ions across the sarcolemma in a regenerative process.