Gas exchange

Learning objectives

Describe the human gas exchange system — trachea, bronchi, bronchioles, alveoli and capillary network — and where cartilage, ciliated epithelium, goblet cells, smooth muscle, squamous epithelium and capillaries occur along it.

Recognise these tissues and airways in slides, photomicrographs and electron micrographs, and draw plan diagrams of transverse sections through the wall of the trachea and of a bronchus.

Describe how ciliated epithelial cells, goblet cells and mucous glands keep the airways clean, and what cartilage, elastic fibres, smooth muscle and squamous epithelium each contribute to the lungs.

Explain gas exchange between alveolar air and capillary blood by diffusion, relating surface area, diffusion distance and the concentration gradients maintained by ventilation and blood flow to the rate of exchange.