IB Biology: B3.1-Adaptations of the Lungs for Gas Exchange

Front

What are alveoli?

Back

Microscopic spheres in the lungs that increase surface area for gas exchange.

Front

Why do alveoli have a thin epithelial layer?

Back

To minimize diffusion distances for respiratory gases.

Front

What surrounds the alveoli to aid in gas exchange?

Back

A rich capillary network.

Front

Why are alveoli roughly spherical in shape?

Back

To maximize the available surface area for gas exchange.

Front

What covers the internal surface of the alveoli?

Back

A thin layer of phospholipid and protein called surfactant.

Front

What is the function of surfactant in the alveoli?

Back

Reduces surface tension and prevents alveolus from collapsing during breathing.

Front

Which cells secrete surfactant?

Back

Type II pneumocytes.

Front

How does surfactant aid in gas exchange?

Back

Allows oxygen to dissolve and diffuse into the blood and CO2 out.