Title: Cardiac physiology - Wikipedia
Headings: Cardiac physiology
Cardiac physiology
Contents
Blood flow
Cardiac muscle
Structure of cardiac muscle
Electrical conduction
Sinoatrial (SA) node
Atrioventricular (AV) node
Bundle of His, bundle branches, and Purkinje fibers
Membrane potentials and ion movement in cardiac conductive cells
Membrane Potentials and ion movement in cardiac contractile cells
Calcium ions
Comparative rates of conduction system firing
Cardiac cycle
Pressures and flow
Phases of the cardiac cycle
Atrial systole and diastole
Ventricular systole
Ventricular diastole
Heart sounds
Heart rate
Cardiovascular centres
Factors influencing heart rate
Cardiac output
Stroke volume
Preload
Afterload
Contractility
See also
References

Content: Their function is similar in many respects to neurons. The bundle of His and Purkinje fibres are specialised cardiomyocytes that function in the conduction system. Structure of cardiac muscle
Details of intercalated discs
Cardiomyocytes, are considerably shorter and have smaller diameters than skeletal myocytes. Cardiac muscle (like skeletal muscle) is characterized by striations – the stripes of dark and light bands resulting from the organised arrangement of myofilaments and myofibrils in the sarcomere along the length of the cell. T (transverse) tubules are deep invaginations from the sarcolemma (cell membrane) that penetrate the cell, allowing the electrical impulses to reach the interior. In cardiac muscle the T-tubules are only found at the Z-lines. When an action potential causes cells to contract, calcium is released from the sarcoplasmic reticulum of the cells as well as the T tubules. The calcium release triggers sliding of the actin and myosin fibrils leading to contraction. A plentiful supply of mitochondria provide the energy for the contractions. Typically, cardiomyocytes have a single, central nucleus, but can also have two or more.