DEMO|TOPIC 07-GASEOUS EXCHANGE AND RESPIRATION

 

TOPIC 07-GASEOUS EXCHANGE AND RESPIRATION

Gaseous exchange

Gaseous exchange is the movement of oxygen and carbon dioxide across a respiratory surface. Unicellular organisms carry out gaseous exchange by diffusion across the cell membrane. Large organisms cannot carry out diffusion efficiently so they have developed specialized organs for gaseous exchange. These are called respiratory surfaces.

Table below shows examples of respiratory surfaces in various organisms.

Respiratory surfaces in various organisms

Organism	Respiratory surface
Amoeba	Cell membrane
Insects	Tracheal system
Spider	Book lung
Fish	Gills
Plants   Leaves, stems, roots
Amphibians   Skin, gills and lungs
mammals   Lungs
Birds	Lungs
Reptiles	Lungs

Characteristics of respiratory surfaces

1. They are thin to reduce the diffusion distance.

2. They are moist to dissolve gases so that they diffuse in solution form.

READ MORE