Respiratory System: Breathing and Gas Exchange

Gas Exchange in Organisms

• The process of exchanging O2 from the atmosphere with CO2 produced by cells is commonly known as respiration.

Simple Diffusion in Organisms

• Simple multicellular organisms, such as flatworms, exchange O2 with CO2 by simple diffusion over their entire body surface.

Gas Exchange in Earthworms

• Moist cuticles help earthworms exchange gases by maintaining a thin layer of moisture on their skin, allowing for diffusion of gases.
• Earthworms use a respiratory mechanism involving contraction and relaxation of their body muscles to facilitate gas exchange.

Insects' Respiratory System

• The main gas exchanged by insects through their network of tracheal tubes is oxygen (O2).
• Insects use tracheae to transport atmospheric air within their bodies for gas exchange.

Gas Exchange in Lower Invertebrates

• Lower invertebrates like sponges exchange gases through diffusion from the surrounding water into their cells.
• This process occurs through their large surface area-to-volume ratio, allowing for efficient diffusion of gases.

Importance of Oxygen

• The main purpose of oxygen (O2) for organisms is to support cellular respiration, which releases energy from nutrients.

Harmful Gas Released

• The harmful gas released during catabolic reactions in organisms is carbon dioxide (CO2).