Blood pressure, the pressure at which the blood flows through the vessels of the body, needs to remain at a healthy level. The normal pressures for the average adult are around 120/80. Hypertension begins when the numbers rise above the normal reading. A blood pressure cuff is a fairly simple instrument used to measure the blood pressure. Some parts of the cuff constrict blood flow to allow other parts to accurately measure the pressures in the blood vessels.
The inflatable cuff, the outer arm jacket piece that fits around the arm, tightens as the pressure begins to seal the vessels in the arm, bringing the pressure to a key point for the reading of the systolic, or top number, in the blood pressure reading. The pressures of the cuff drop when the reading tapers off to the diastolic, or lower number, the last beat heard through the stethoscope placed over the artery on the inside of the arm over the elbow.
The rubber tube that measures approximately 1/4 inch in diameter connects to the gauge and cuff. It holds the air as it becomes pumped into the cuff from the bulb attached to its end piece.
The gauge contains the dial with a pointer that indicates the top and bottom parts of the reading of the blood pressure. The pointer circles around the numbers on the gauge and visibly depicts the upper and lower numbers as they pertain to the blood pressure reading.
The squeeze bulb attached to the blood pressure cuff works to pump air into the cuff. As the bulb is squeezed, air pressure builds up in the cuff, which makes it tighten around the arm so the gauge can read the blood pressure. The bulb also contains a pressure release valve that holds the cuff pressure steady, then allows the person taking the reading to release air pressure.