Term

Why do large organisms need specialised exchange surfaces?

Definition

- low SA:V ratio - larger so greater diffusion distance - high metabolic demand that can't be met by only diffusion

Term

What are the features of efficient exchange surfaces and how do they link to efficiency?

Definition

- large surface area so more diffusion can happen at once - thin layers for shorter diffusion distance - good blood supply maintains steep concentration gradient for quick diffusion - ventilation to maintain steep concentration gradient

Term

What are the structures of the human gas exchange system and their functions?

Definition

trachea: - carries air to and from the lungs - branched and lined with a ciliated epithelium with goblet cells that secrete mucus to trap dust and pathogens - supported by cartilage rings that stop it from collapsing bronchi: - carry air from the trachea into each lung - also has cartilage rings bronchioles: - carry air deeper into the lungs - walls contain smooth muscle, which can contract to narrow the airway or relax to widen it alveoli: - site of gas exchange