Gas Exchange in mammals
- Created by: Lauren Lovick
- Created on: 17-10-09 20:58
Gases + nutrients need to enter organisms across exchange surfaces (usually cell membranes)
They also need to exchange waste products eg CO2
Smaller organisms have a higher SA:V ratio (think of mouse Vs hippo)
Amoeba have a v. high SA:V ratio - this is why they can exchange substances over a whole surface by diffusion
Larger, multicellular organsisms have a lower SA:V ratio - they require specialised exchange surfaces with large SA's
Animals release heat from respiration, so larger animals are more likely to overheat, and smaller animals spend a lot of energy keeping warm as they easily lose heat (high SA:V ratio).
---
In mammals, the specialised exchange surface is the lungs
Cartilage: add strength + flexibility, keep trachaea open
Cilia: line the trachaea, bronchi, bronchioles. Waft mucous + trapped particles up and out to protect the lungs
Goblet cells: produce mucous to trap dust + other inhaled particles
Smooth muscle: around bronchi + bronchioles. Involuntary muscle contractions can narrow airways
…
Comments
No comments have yet been made