IB Biology SL B3.1.5 Lung Ventilation Questions

Explore how inspiration and expiration arise from coordinated respiratory-muscle contraction, thoracic pressure changes and airflow in IB Biology SL B3.1.5.

Exam points

Trace inspiration from diaphragm and external-intercostal contraction through increased thoracic volume and reduced lung pressure to airflow in.
Trace expiration from reduced thoracic volume and increased lung pressure to airflow out, including forced-expiration muscle actions.
Interpret pressure, spirometry or exercise data to identify muscle timing, airflow direction and changes in tidal or minute ventilation.

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Study B3.1.5—Lung ventilation conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 8]

Explain the need for a ventilation system and the mechanism of ventilation of the lungs in humans

a. (cellular) respiration drives the need for gas exchange/absorption of oxygen and removal of $\mathrm{CO}_{2}$ ;
b. gas exchange depends upon a ventilation system;
c. lungs/alveoli provide surface area for gas exchange (with capillaries/blood);
d. ventilation system maintains a high concentration of oxygen in the alveoli;
e. bloodstream links alveoli to cells;
f. inhalation by contraction of diaphragm;
g. inhalation occurs with contraction of external intercostals/relaxation of internal intercostals;
h. (these) increase the volume/reduce the pressure in thorax, pulling air into lungs;
i. exhalation caused by relaxation of the diaphragm;
j. exhalation occurs with relaxation of external intercostals/contraction of internal intercostals;
k. (these) decrease volume/increase pressure in the thorax, forcing air out of lungs;

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IB Biology SL B3.1.5 Lung Ventilation Questions question 1