Importance of Gaseous Exchange in Organisms:

• Provides energy
• Removes CO2 and supplies O2

Gaseous Exchange in Lungs:

• Occurs in alveoli by diffusion
• O2 diffuses from inhaled air into the blood
• CO2 diffuses from the blood into the lungs and is exhaled
• Haemoglobin plays a crucial role

Gaseous Exchange in Tissues:

• O2 diffuses from capillaries into tissue fluid
• CO2 diffuses from tissue fluid into the blood for removal
• CO2 is carried as H2CO3