In this IBDP Biology post, we will be discussing the importance of a ventilation system, and how our system differs from other organisms.
The need for a Ventilation System
Respiration - characteristic of life.
Biological meaning - release of energy. Cellular respiration goes on in every living cell. Most cells require a constant supply of oxygen to finction.
Large organisms need to maintain a gas exchange and therefore a smaller surface area over volume ration. The decrease of surface area over volume ration is rapid as the size of the organism increases.
Example 1
The smaller cube:
- The surface area is 6 x 1 x 1 cm2 = 6 cm2
- The volume is 1 x 1 x 1 cm3 = 1 cm3
- The surface area over volume ratio is 6/1 = 6
The larger cube:
- The surface area is 6 x 10 x 10 cm2 = 600 cm2
- The volume is 10 x 10 x 10 cm3 = 1 000 cm3
- The surface area over volume ratio is 600/1000 = 0.6
- This means that the smaller cube has 6cm2 for every cm3 of volume.
So when organisms become larger, there is not enough surface area for gas exchange.
In large animals, surface area needs to be increased, and diffusion distance decreased.
Lungs for example help - a ventilation movement refreshed air in the fine capillary network of the alveoli which have a large surface area, moist and a good blood supply.
The concentration gradient across the respiratory surface is maintained in 3 ways - blood flow on one side, and air flow on the other. The ventilation replaces diffused oxygen and removes CO2.
That's all for the importance of the ventilation system!
References:
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fbiology4ibdp.weebly.com%2F64-gas-exchange1.html&psig=AOvVaw3c1SMYzAXsOQaVEj4YprFQ&ust=1626596962249000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCKiUy4PY6fECFQAAAAAdAAAAABAD
Drafted By Venetia (Biology)