Final answer:
A blood pressure cuff works by inflating a cuff around the arm to measure blood pressure; the heart beats faster when changing body positions to maintain blood flow due to gravitational effects.
Step-by-step explanation:
The question asks about how a blood pressure cuff works and why the heart would need to beat faster when changing body positions from lying down to sitting, and then to standing. To explain in simple terms, the blood pressure cuff, also known as a sphygmomanometer, is a device used to measure blood pressure. It consists of an inflatable cuff attached to a measuring device and a stethoscope. A clinician wraps the cuff around the patient’s arm, inflates it to apply pressure on the artery, and then slowly releases the air while listening for blood flow sounds to determine blood pressure readings. The heart needs to beat faster when changing positions because standing up quickly can cause blood to pool in the legs due to gravity, which reduces the amount of blood returning to the heart. To maintain blood flow to the brain and other vital organs, the heart compensates by beating faster.