mechanism of ventilation in fish and insects Flashcards
name and describe the two main features of a fish’s transport system
gills: located within the body, supported by arches, along which are multiple projections of gill filaments, which are stacked up in piles
lamellae: at right angles to the gill filaments, give an increased surface, blood and water flow across them in opposite directions (counter-current exchange system)
explain the process of gas exchange in fish
- buccal cavity volume increased to enable water to flow in, reduced to increase pressure
- water is pumped over the lamellae by the operculum, oxygen diffuses into the bloodstream
- waste carbon dioxide diffuses into the water and flows back out of the gills
how does the countercurrent exchange system maximise oxygen absorbed by the fish?
- maintains a steep concentration gradient, as water is always next to blood of a lower oxygen concentration
- keeps rate of diffusion constant and enables 80% of available oxygen to be absorbed
name and describe the 3 main features of an insect’s gas transport system
spiracles: holes on the body’s surface which may be opened or closed by a valve for gas or water exchange
tracheae: large tubes extending through all body tissues, supported by rings to prevent collapse
tracheoles: smaller branches dividing off the tracheae
explain the process of gas exchange in insects
- gases move in and out of the tracheae through spiracles
- a diffusion gradient allows oxygen to diffuse into the body tissue while waste CO2 diffuses out
- contraction of muscles in the tracheae allows mass movement of air in and out