Because animals cannot produce energy directly from the sun, they must eat plants or other animals that eat plants, and acquire energy, either directly or indirectly, from glucose
The heart has an intrinsic conduction system that causes electrical activity in the heart muscles causing them to contract. The intrinsic conduction system is made up specialized cells, that contain nerve and muscular characteristics.
The muscle cells in the heart are linked together by gap junctions, allowing cardiac action potentials to travel from one muscle cell to another.
Atrioventricular (AV) node. The damage to the AV node causes the electrical signals traveling from the upper chambers to the lower chambers to be impaired causing an AV block.
