| Anatomy of the Heart | ||||||||
Chambers The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. Valves allow blood to flow in one direction between the chambers of the heart. Heart Wall The heart wall is divided into three layers: Cardiac Conduction Cardiac conduction is the rate at which the heart conducts electrical impulses. Cardiac muscle cells contract spontaneously and are coordinated by nodal tissue, specifically the sinoatrial node. There are other factors that influence heart rate as well. These include endocrine hormones, body temperature and exercise. Cardiac Cycle The cardiac cycle is the sequence of events that occur when the heart beats. There are two phases of this cycle: Share Your Opinions Have questions about the heart? Come on over to the Biology Forum and share your thoughts, opinions and feelings. |
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