Blood pressure is the pressure of the blood being pumped against the walls of the arteries. The heart contracts, pushing the blood through the valves and relaxes to refill it with blood again.
Sphygmomanometer is the medical term given to a Blood Pressure Apparatus, used to measure the blood pressure of an individual.
The basic manual sphygmomanometer consists of an inflatable cuff attached with tubes and an air control valve with an inflation bulb. This cuff is also attached to a manometer (a gauge filled with mercury or a dial gauge) which shows the pressure reading. This manual apparatus is typically used with a stethoscope.
The cuff is usually inflated to a high pressure in the upper arm so that no blood can pass through the artery above the elbow. The pressure is very slowly released until the blood squirts through little by little. A stethoscope is used to hear and mark the reading when the squirting starts (high) and stops (low) with ongoing slow loosening of the pressure valve till its released completely. The systolic (high) and diastolic (low) pressure recorded makes a blood pressure reading.
In this day and age, digitally enhanced blood pressure monitors are used by everyone for domestic purposes. Since blood pressure may not have any symptoms before it is dangerously high or low, it is advisable for patients to check their blood pressure regularly. These digital equipments are compact and easy to use with either automatic inflating cuffs or those, which come with an inflation bulb.
Though digital monitors are becoming immensely popular and an essential tool to have around, these monitors are not as accurate as when compared to the manual apparatus. However, this can definitely be used as a guide and an indication for when an approaching visit to a medical practitioner is unavoidable when it shows a low or high blood pressure reading.