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.
- Rate, infant mortality
The 1997 infant mortality rate for the United States, according to preliminary data, was 7.1 deaths per 1,000 births, substantially below the 1983 rate of 10.9. Infant mortality data are available by mother’s race and ethnicity through 1996. Black, non-Hispanics have consistently had a higher infant mortality rate than white, non-Hispanics. In 1996, the black, […]
- Rate, maternal mortality
The number of maternal deaths related to childbearing divided by the number of live births (or by the number of live births + fetal deaths) in that year. The maternal mortality rate in the United States in 1993 (and 1994) was 0.1 per 1,000 live births, or 1 mother dying per 10,000 live births.
- Rate, mortality
The number of maternal deaths related to childbearing divided by the number of live births (or by the number of live births + fetal deaths) in that year. The word “mortality” came from the Latin “mors” (death). Mortality is distinct from morbidity (illness). A condition such as tuberculosis can cause morbidity and mortality (disease and […]
- Rate, neonatal mortality
The number of children dying under 28 days of age divided by the number of live births that year. The neonatal mortality rate in the United States, which was 8.4 per 1,000 live births in 1980, declined to 5.8 per 1,000 live births in 1990.
- Rate, pulse
The pulse rate is most often taken at the wrist. It measures the number of pulsations in the radial artery each minute. This most often reflects heart rate.