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B3.2.3—Artery adaptations

Arteries withstand and maintain high-pressure blood flow using thick collagen-rich walls, smooth muscle layers, elastic recoil and relatively narrow lumens.

Syllabus
First assessment 2025
Objective
B3.2.3
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–3

Common command terms

  • Identify
  • Explain

Scoring notes

Common mistake
Saying arteries pump blood by themselves rather than explaining elastic recoil after ventricular contraction.

Recent exam appearances

November 2024Paper1 ["HL"] · TZ022[ 1 ]B3.2.3—Artery adaptations
May 2021Paper1 ["HL"] · TZ120[ 1 ]B3.2.3—Artery adaptations
November 2020Paper3 ["HL"] · TZ02(c)[ 3 ]B3.2.3—Artery adaptations
November 2014Paper2 ["HL"] · TZ01(c)[ 2 ]B3.2.3—Artery adaptations
Practice this objective

Coverage 2014–2024 · Updated 15 Jul 2026

Artery Walls Withstand Pulse Pressure

Arteries have thick muscular and elastic walls that maintain a lumen and smooth pressure pulses from the heart.

Elastic recoil helps keep blood moving between heartbeats, while smooth muscle adjusts diameter and resistance. The wall must withstand higher pressure than a vein.

Separate pulse smoothing from resistance control: which wall feature does each job?

A constricted arteriole raises resistance and can redirect blood flow, whereas elastic recoil in a large artery smooths the pulse.

A thick wall does not mean blood always flows faster; diameter, resistance and downstream demand also matter.

Artery adaptations

Assessment in practice

1–3 marks
How it is assessed

This objective is assessed through structured response, commonly using Identify / Explain.

Command terms

Identify / Explain

What earns marks

Build the answer around this relationship: Thick collagen-rich artery walls resist rupture under high pressure.

Watch for

Saying arteries pump blood by themselves rather than explaining elastic recoil after ventricular contraction.

Representative question

Question 1

[Maximum number: 5]

Explain how the structure of an artery allows it to carry out its function efficiently.

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

  • Thick collagen-rich artery walls resist rupture under high pressure.
  • Elastic fibres stretch and recoil to maintain flow between heartbeats.
  • Smooth muscle can change vessel diameter and help regulate blood distribution.
  • A narrow lumen helps maintain arterial pressure.