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The cardiomyocytes make up the bulk (99%) of cells in the atria and ventricles. These contractile cells respond to impulses of action potential from the pacemaker cells and are responsible for the contractions that pump blood through the body. The pacemaker cells make up just (1% of cells) and form the conduction system of the heart.
[1] [2] Only one percent of the heart muscle cells are conductive, the rest of the cardiomyocytes are contractile. The pacemaker cells are connected to neighboring contractile cells via gap junctions, which enable them to locally depolarize adjacent cells. Gap junctions allow the passage of positive cations from the depolarization of the ...
The action potential passes along the cell membrane causing the cell to contract, therefore the activity of the sinoatrial node results in a resting heart rate of roughly 60–100 beats per minute. All cardiac muscle cells are electrically linked to one another, by intercalated discs which allow the action potential to pass from one cell to the ...
Autorhythmic cells do not contract, but instead set the pace of contraction for other cardiac muscle cells, which can be modulated by the autonomic nervous system. In contrast, contractile muscle cells (cardiomyocytes) constitute the majority of the heart muscle and are able to contract.
The main pumps involved are: the sarcoplasmic reticulum Ca 2+-ATPase, which pumps Ca 2+ back into the SR, the Sarcolemmal sodium-calcium exchanger, which pumps one Ca 2+ out of the cell, in exchange for 3 sodium ions being pumped into the cell, the Sarcolemmal Ca 2+-ATPase, which uses ATP to pump Ca 2+ directly out of the cell and the ...
The cardiac conduction system (CCS, also called the electrical conduction system of the heart) [1] transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the body's circulatory system.
The cells are surrounded by an extracellular matrix produced by supporting fibroblast cells. Specialised modified cardiomyocytes known as pacemaker cells, set the rhythm of the heart contractions. The pacemaker cells are only weakly contractile without sarcomeres, and are connected to neighboring contractile cells via gap junctions. [3]
The connective tissue, along with the paranodal cells, insulate the SA node from the rest of the atrium, preventing the electrical activity of the atrial cells from affecting the SA node cells. [2] The SA node cells are smaller and paler than the surrounding atrial cells , with the average cell being around 8 micrometers in diameter and 20-30 ...