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blood pressure

the pressure exerted by the blood against the walls of blood vessels, especially arteries. It varies with the strength of the heartbeat, the elasticity of the artery walls and resistance of the arterioles, and the person’s health, age, and state of activity. Blood pressure is measured using an instrument called a sphygmomanometer. The pressure measured during heart contraction (see systolic blood pressure) is higher than that measured when the heart is relaxed (see diastolic blood pressure). The readings are recorded (in millimeters of mercury) as systolic/diastolic; the normal resting blood pressure for an adult is less than 120/80. See also hypertension.

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Psychology term of the day

February 1st 2025

A fiber

A fiber

a myelinated nerve fiber (axon) of the somatosensory system. A fibers are subdivided by diameter, ranging from largest to smallest: A-alpha fibers are 13 to 20 μm in diameter and transmit information from proprioceptors of skeletal muscles, A-beta fibers are 6 to 12 μm and transmit information from mechanoreceptors of the skin, and A-delta fibers are 1 to 5 μm and transmit temperature and sharp pain information. See also B fiber; C fiber.