Topic 6.4: Gas Exchange
Essential Idea: The lungs are actively ventilated to ensure that gas exchange can occur passively.
At SHS, Topic 6.4 is taught in the following class unit(s):
Statements & Objectives:
6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air and alveolu and blood flowing in adjacent capillaries.
6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.
6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.
6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.
6.4.U5 Muscle contraction causes the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
6.4.U6 Different muscles are required for inspiration and expiration because muscles only do work when they contract.
6.4.A1 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.
6.4.A2 Causes and consequences of lung cancer.
6.4.A3 Causes and consequences of emphysema.
6.4.S1 Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)
6.4.NOS Obtain evidence for theories- epidemiological studies have contributed to our understanding of the causes of the lung cancer.
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