Circulation and Diffusion in Fish

Fish Circulation and Respiration

Fish have a specialized circulation system where the heart pumps blood through arteries to the gills. Oxygen is extracted from the water as it flows over the gills, allowing carbon dioxide to be expelled. This process requires efficient blood flow to ensure a high concentration gradient for gas exchange.

Gas Exchange Process

Oxygen must be dissolved in water for extraction. The exchange of gases (oxygen and carbon dioxide) between blood and water occurs through diffusion, which is the movement of substances from an area of higher concentration to an area of lower concentration across a semi-permeable membrane. In fish, blood with high carbon dioxide concentration travels to the gills where it exchanges this carbon dioxide for oxygen from the water. This efficient gas exchange is critical for respiratory function in aquatic environments.