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B3.2.4—Pulse rate measurement

Pulse rate reflects pressure waves from ventricular contraction and can be measured by counting arterial pulses over a defined time.

Syllabus
First assessment 2025
Objective
B3.2.4
Level
HL

Exam analysis

Chance of appearing1%of analysed past papers
Latest appearanceMay 2018
Most common paperPaper3
Typical marks2

Common command terms

  • Outline

Recent exam appearances

May 2018Paper3 ["HL"] · TZ222(a)[ 2 ]B3.2.4—Pulse rate measurement
Practice this objective

Coverage 2018–2018 · Updated 15 Jul 2026

Pulse Rate Is a Repeated Pressure Signal

Pulse rate is the number of arterial pressure waves per minute, normally corresponding to ventricular contractions.

Place fingertips—not the thumb—lightly over the radial artery at the wrist or the carotid artery in the neck. Count waves for a known interval while the subject is still and use a full minute when maximum accuracy is needed.

Pulserate(beatsmin−1)=pulsecount×(60s÷countingintervalins).Pulse rate (beats min⁻¹) = pulse count × (60 s ÷ counting interval in s).

Counting 18 pulses in 15 s gives 18 × (60/15) = 72 beats min⁻¹. Repeat after recovery and compare with a digital heart-rate sensor recorded over the same interval.

Short counts magnify counting error, and pulse rate is not cardiac output: cardiac output also depends on stroke volume. Record posture, activity and method when comparing results.

Pulse rate measurement

Assessment in practice

2 marks
How it is assessed

This objective is assessed through structured response, commonly using Outline.

Command terms

Outline

What earns marks

Build the answer around this relationship: Pulse is an arterial pressure wave produced by ventricular contraction.

Representative question

Question 1

[Maximum number: 2]

Outline one method that the researchers could have used to measure heart rate in this study.

Link Transport Structure To Function

Animal and plant transport answers should link structure to function. In animals, capillaries exchange, arteries maintain high-pressure flow, veins return low-pressure blood, pulse measures arterial pressure waves, and coronary occlusion blocks oxygen delivery to heart muscle. In plants, xylem transports water by transpiration tension and cohesion, while stem and root tissue plans show where xylem and phloem are arranged.

  • Blood vessel answers need structure plus pressure or exchange function.
  • Xylem answers need transpiration pull, cohesion, adhesion, lignin, pits, and hollow vessels when relevant.
  • Plant diagrams should identify tissue distribution: stem vascular bundles in a ring, root xylem cross with phloem between arms.

Concept essentials

  • Pulse is an arterial pressure wave produced by ventricular contraction.
  • Pulse rate is usually reported as beats per minute.
  • Radial and carotid arteries are common sites for manual pulse measurement.
  • Short pulse counts can be scaled only when timing and rhythm are reliable.