a) Communication between the cells of the heart is very important for its functioning in the body of the mouse where it is expected to deliver blood continuously and adapt to changes within the organism. The cardiac muscle cell is found in the cardiac muscle tissues of the heart specifically the myocardium, therefore is surrounded by other cardiac muscle cells (myocardioctes) and other cardiac cells such as cardiomycocytes.
These cells of the myocardium are self contracting and are autonomically regulated they contract in a rhythmic fashion throughout the life of the mouse. For this to occur the cells in the tissue have special features, between these Y shaped cells there are intercalated disks that contain gap junctions which provide communicating channels between the cells.
Gap junctions are a type of communicating junction, they can be described as protienaceous tubes that correct adjacent cells. They are formed from connexins which in turn form connexins, they allow the passage of inorganic ions and small water soluble molecules to pass from one cell cytoplasm to another also they can couple cells electrically
The intercalated disks allow waves of depolarization to sweep across the cells which synchronize muscle contraction in the heart. This occurs when ions pass between cells of the cardiac tissue, the ions that does this is Ca2+. When intracellular Ca2+ concentration is low the gap junctions open, when the concentration is high the close. This allows extracellular Ca2+ to enter and create the action potential, it occurs rapidly and can be reversed since the cells can regulate their permeability of their gap junctions.
b b) http://alienbiochemistry.wordpress.com/ (group part)