Which scientific instrument is used to measure human blood pressure?

Introduction / Context:
This general science question checks awareness of basic medical instruments that are commonly used in clinics and hospitals. Blood pressure measurement is a fundamental part of assessing cardiovascular health, and knowing the correct name of the device that performs this function is important for students preparing for exams and for general health literacy.

Given Data / Assumptions:

• The task is to identify the instrument used specifically for measuring human blood pressure.
• The options mention several familiar devices used in medical or scientific contexts.
• Only one of these instruments is dedicated to blood pressure measurement.

Concept / Approach:
A sphygmomanometer is the standard instrument used to measure arterial blood pressure. It typically consists of an inflatable cuff, a measuring unit and often a stethoscope to listen to arterial sounds. Other instruments mentioned in the options have different purposes, so the key is to match each device with its primary function and select the one that relates directly to blood pressure.

Step-by-Step Solution:
Step 1: Recall the definition of a sphygmomanometer as the instrument for measuring blood pressure. Step 2: Recognise that a manometer is a general pressure measuring device often used for gases or fluids in laboratory settings. Step 3: Note that a thermometer measures temperature, not blood pressure. Step 4: Understand that a stethoscope helps listen to internal body sounds such as heartbeats and lung sounds, but does not measure pressure on its own. Step 5: Conclude that sphygmomanometer is the only option that correctly matches the function described.

Verification / Alternative check:
Medical professionals routinely use a sphygmomanometer on the upper arm to obtain systolic and diastolic blood pressure readings. This term appears in health reports, textbooks and instructions printed on digital blood pressure monitors. None of the other options are labelled or marketed as blood pressure instruments, which serves as a reliable confirmation of the correct answer.

Why Other Options Are Wrong:
Manometer: A general pressure measuring device, but not specifically used as the standard instrument for human blood pressure in clinical practice.
Thermometer: Designed to measure body or environmental temperature, not blood pressure.
Stethoscope: Used to listen to internal sounds and often used together with a sphygmomanometer, but does not itself measure pressure values.

Common Pitfalls:
Learners sometimes confuse the roles of instruments used together. Because a stethoscope is often seen with a blood pressure cuff, some candidates wrongly assume it is the measuring device. Others may pick manometer based on the root word manometry for pressure measurement. Remembering that sphygmomanometer is the specialised term for blood pressure measurement avoids these mistakes.

Final Answer:
The scientific instrument used to measure human blood pressure is the sphygmomanometer.