exchange surfaces Flashcards
What sized animals have the best SA:V ratio?
small ones
Why do multicellular organisms need exchange surfaces?
cells are deep in the body so diffusion distance is too long, low SA:V ratio and high metabolic rate
What 4 things do specialised exchange surfaces have?
short diffusion distance, good blood supply, well ventilated and a large surface area
Describe the pathway of air when it enters mammals?
through mouth/nose into trachea, into bronchi, into bronchioles and then to alveoli
What type of cells line the trachea, bronchi and bronchioles?
ciliated epithelium
How do goblet cells trap microorganisms?
secretion of mucus
During expiration how do elastic fibres help?
they recoil after stretching to force out air
How are the trachea prevented from closing?
C-shaped pieces of cartilage
