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IB Biology HL B3.3.8 Hl Intercostal Muscles Questions

Practise distinguishing how external intercostals lift the ribs up and out for inspiration while internal intercostals pull them down and in during forced expiration.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain that external intercostal muscles contract to lift the ribs up and out during inspiration, increasing thoracic volume and lowering pressure.
  • Explain that internal intercostal muscles contract to pull the ribs down and in during forced expiration, reducing thoracic volume and raising pressure.
  • Distinguish the antagonistic external- versus internal-intercostal actions and use rib direction or pressure evidence to identify inspiration or forced expiration.

IB Biology HL B3.3.8 Hl Intercostal Muscles Questions question 1

[Maximum number: 1]

What occurs during inspiration?

A

Internal intercostal muscles contract, increasing the pressure in the thorax.

B

Internal intercostal muscles contract, decreasing the pressure in the thorax.

C

External intercostal muscles contract, decreasing the pressure in the thorax.

D

External intercostal muscles contract, increasing the pressure in the thorax.

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