Evolution of the animal respiratory system

In this topic

• Why gas exchange is needed, and the rule it obeys
• From the body surface to a moist skin
• The aquatic solution — gills
• Land solutions and the growing complexity of lungs

Key terms

• Gas exchange
• Diffusion
• Surface-to-volume ratio
• Cutaneous (skin) respiration
• Gill
• Countercurrent flow
• Tracheal system
• Spiracle
• Book lung
• Alveolus
• Air sacs
• Diaphragm

Read the full topic

The lesson text, diagrams and 20 test questions are on the site — register free to open them.

UZRU