Cardiac muscle cell fatigue. There are two types of cells within the heart: the cardiomyocytes and the cardiac pacemaker cells. Cardiomyocytes make up the atria (the chambers in which blood enters the heart) and the ventricles (the chambers where blood is collected and pumped out of the heart). These cells must be able to shorten and lengthen their fibers and the fibers must be flexible enough to stretch. These functions are critical to the proper form during the beating of the heart. Cardiac pacemaker cells carry the impulses that are responsible for the beating of the heart. They are distributed throughout the heart
Cardiac physiology large numbers of gap junctions that allow the passage of ions between the cells and help to synchronize the contraction. Intercellular connective tissue also helps to strongly bind the cells together, in order to withstand the forces of contraction. Cardiac muscle undergoes aerobic respiration patterns, primarily metabolizing lipids and carbohydrates. Oxygen from the lungs attaches to haemoglobin and is also stored in the myoglobin, so that a plentiful supply of oxygen is available. Lipids, and glycogen are also stored within the sarcoplasm and these are broken down by mitochondria to release ATP. The cells undergo twitch-type contractions with long refractory