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.

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.

$Pulse rate (beats min⁻¹) = pulse count × (60 s ÷ counting interval in s).$

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.

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

[Maximum number: 2]

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

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.

B3.2.4—Pulse rate measurement

Pulse Rate Is a Repeated Pressure Signal

Pulse rate measurement

Assessment in practice

Link Transport Structure To Function

Concept essentials

Question 1