| 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) |
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| rate, infant mortality | The number of children dying under a year of age divided by the number of live births that year. The infant mortality rate in the united states, which was 12.5 per 1,000 live births in 1980, fell to 9.2 per 1,000 live births in 1990. (12 Dec 1998) |
| rate-limiting step | <biochemistry> The slowest step in a metabolic pathway, or the step in an enzymatic reaction that requires the greatest amount of energy to initiate. (17 Dec 1997) |
| 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 + foetal 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. (12 Dec 1998) |
| rate meter | A device that continuously displays the magnitude of events averaged over varying time intervals. (05 Mar 2000) |
| 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. (12 Dec 1998) |
| rate, pulse | The pulse rate is most often taken at the wrist. It measures the number of pulsations in the radial artery each minute. (12 Dec 1998) |
| rate, respiratory | The number of breaths per minute (or, more formally, the number of movements indicative of inspiration and expiration per unit time). In practice, the respiratory rate is usually determined by counting the number of times the chest rises (or falls) per minute. By whatever means, the aim is to determine if the respirations are normal, abnormally fast (tachypnea), abnormally slow (technically termed bradypnea), or nonexistent (apnea). (12 Dec 1998) |
| rate schedule | A price list showing how the electric bill of a particular type of customer will be calculated by an electric utility company. (05 Dec 1998) |
| rate, sed | A sedimentation rate, or sed rate , is a blood test that detects and is used to monitor inflammation activity. It is measured by recording the rate at which red blood cells (rbcs) sediment in a tube over time. It increases (the rbcs sediment faster) with more inflammation. (12 Dec 1998) |
| rate, sedimentation | A sedimentation rate, or sed rate , is a blood test that detects and is used to monitor inflammation activity. It is measured by recording the rate at which red blood cells (rbcs) sediment in a tube over time. It increases (the rbcs sediment faster) with more inflammation. (12 Dec 1998) |
| rate setting and review | A method of examining and setting levels of payments. (12 Dec 1998) |
| recurrence rate | In genetic counseling, the risk that a future offspring will be affected given some specific set of relatives of whom at least one is already affected. (05 Mar 2000) |
| case fatality rate | The proportion of individuals contracting a disease that die of that disease. (05 Mar 2000) |
| maternal death rate | The number of maternal deaths that occur as the direct result of the reproductive process per 100,000 live births. See: rate. See: maternal death. (05 Mar 2000) |