quiz 24 Flashcards
What is the function of the small intestine?
Digests food and absorbs small nutrient molecules into the bloodstream
How does the oxygen we breath in reach the bloodstream?
Diffusion from the lungs
What gas diffuses out of the bloodstream into the lungs?
carbon dioxide
What are 3 factors that can affect the rate of diffusion?
concentration gradient,temperature and surface area
Define exchange surface
A surface which exchanges molecules between one area and another
Define gas exchange
When oxygen moves into the bloodstream from the lungs and carbon dioxide moves out of the bloodstream into the lungs
Define ventilation
The movement of air or water in and out of an exchange organ
Where does gas exchange take place in lungs?
alveoli
Explain why exchange are well ventilated
To maintain a steep concentration gradient which increases the rate of diffusion
Why do multicellular organisms need exchange surfaces?
As they have a smaller surface area to volume ratio and need to maximise the rate of diffusion
Give 4 adaptations of an exchange surface in animals to maintain a high rate of diffusion
Large surface area,thin membranes,good blood supply and well ventilated
What gas diffuses into the bloodstream from the lungs?
Oxygen
What is the function of fish gills
To absorb oxygen from water and release carbon dioxide(gas exchange)
