Gaseous Exchange In Animals

Introduction:

Animals, like plants, require gaseous exchange for respiration. They take in oxygen and release carbon dioxide to obtain energy from food. Aquatic animals exchange gases with water, containing about 5% oxygen, while terrestrial animals use air, which contains about 21% oxygen. Animals have specialized respiratory surfaces, which can be their body surface or internal structures, facilitating this vital exchange.

Properties of Respiratory Surface:

• Thin:

The respiratory surface is thin, allowing for efficient gas exchange.

• Wet:

It must be moist to facilitate the dissolving of gases.

• Permeable:

It allows gases to pass through easily.

• Large in Relation to Body Volume:

The surface area for gas exchange is proportionally substantial compared to the organism’s body size.

Proportion of Respiratory Surface:

The surface area must be sufficiently large to support gas exchange for all body cells.
For instance, in humans, the total respiratory surface area is approximately 20 times the size of the body.

Respiratory Surfaces - Large Surface Area:

A larger surface area enables efficient gaseous exchange by promoting faster diffusion, which supplies oxygen and eliminates carbon dioxide.
This compensates for the relatively small surface area-to-volume ratio found in many animal bodies.