GASEOUS EXCHANGE

Gaseous Exchange

• Role and structure of alveoli walls = The alveoli are the site of gaseous exchange - oxygen enters the blood and carbon dioxide is removed from it. Three adaptations to increase efficiency. 1. Vast number of air sacs surrounded by capillaries to increase surface area, 2. Walls of the alveoli are very thin and 3. Inner surfaces coated in water to allow oxygen to dissolve before travelling through alveoli and capillaries
• Diffusion gradient = There is a higher concentration of oxygen in inhaled air than there is in the blood. Oxygen diffuses into the blood and combines with the haemoglobin in the erythrocytes, forming oxyhaemoglobin. Carbon dioxide in the blood diffuses in the opposite direction as there are higher levels of this gas in the blood than there is in the alveoli

Respiration

• Cellular respiration = Cellular respiration is why we need oxygen to live. It occurs in the cytoplasm and mitochondria of all living cells
• Role of glucose = Food supplies the energy we need, in particular, a sugar called glucose…