| rate, heart | Number of heart beats per minute. The normal resting adult heart beats regularly at an average rate of 60 times per minute. (young children's hearts beat faster). The speed of the heartbeat (heart rate) is governed by the speed of electrical signals from the pacemaker of the heart, the sa node, located in the right atrium (upper chamber of the heart). The electrical signals from the sa node travel across the atria and cause these two upper heart chambers to contract, delivering blood into the lower heart chambers, the ventricles. The electrical signals then pass through the av node to reach the ventricles. Electrical signals reaching the ventricles cause these chambers to contract, pumping blood to the rest of the body, generating the pulse. During rest, the speed of electrical signals originating from the sa node is slow, so the heart beats slowly. During exercise or excitement, the speed of signals from the sa node increases, and the heartbeat quickens. (12 Dec 1998) |
|---|---|
| venous heart | <anatomy> The right side, including both the atrium and ventricle, of the heart. (05 Mar 2000) |
| ventricles of heart | One of the two lower chambers of the heart. Synonym: ventriculus cordis. (05 Mar 2000) |
| parchment heart | A congenital or acquired condition in which there is thinning of the right ventricular myocardium. Synonym: right ventricular hypoplasia. (05 Mar 2000) |
| vertical heart | Loosely descriptive of the heart's electrical axis when this is directed at approximately +90 |
| partial heart block | Impulses penetrate the atrioventricular junction in some relation to the ventricular rate. Synonym: incomplete atrioventricular block. (05 Mar 2000) |
| mechanical alternation of the heart | A disorder in which contractions of the heart are regular but are alternately stronger and weaker. (05 Mar 2000) |
| mechanical heart | Term loosely applied to any mechanical circulatory assist device. (05 Mar 2000) |
| globular heart | Abnormally smooth arcuate contours of the heart due either to disease of the ventricles or to a false cardiac appearance produced by excessive pericardial fluid. Synonym: globular heart. (05 Mar 2000) |
| vortex of heart | A spiral arrangement of muscular fibres at the apex of the heart. Synonym: vortex cordis, whorl. (05 Mar 2000) |
| pendulous heart | An extreme form of cor mobile in which the heart appears to be suspended by the great vessels. Synonym: pendulous heart. (05 Mar 2000) |
| chaotic heart | Apparently totally uncoordinated cardiac action or rhythm. (05 Mar 2000) |
| rheumatic heart disease | The most important manifestation of and sequel to rheumatic fever, i.e., any cardiac involvement in rheumatic fever. (12 Dec 1998) |
| rheumatism of the heart | Rheumatic cardiac valvular disease, most often of the mitral and aortic valves. (05 Mar 2000) |
| chick heart fibroblast | <cell culture> The cells that emigrate from an explant of embryonic chick heart maintained in culture. Often used as archetypal normal cell. (05 Jan 1998) |