mod 2 Flashcards
Compare and contrast the mechanism of expiration during the first 60 seconds of the trace with
the mechanism of expiration when the subject was told to breathe out fully.
Normal expiration
* passive
* diaphragm muscles relax
* diaphragm moves up / becomes
dome shaped
* external intercostal muscles relax
* ribs move down and in
* elastic fibres recoil
* volume of thorax reduced
* pressure in thorax increased
* pressure in thorax greater than
atmospheric pressure so air
moves out of lungs
Forced expiration
* active
* requires energy
* internal intercostal muscles
contract
* ribs pulled down hard
* abdominal muscles contract
forcing diaphragm up
outline how the respiratory
systems in a bony fish and in an insect are adapted to maximise ventilation and gaseous
exchange.
**bony fish ventilation
**water enters mouth
ref. volume / pressure, change in buccal
cavity
water, flows / pushed, over gills
water leaves via operculum
throughflow system / one direction of flow
**bony fish gas exchange
**gill, filaments / lamellae
large surface area
thin
short diffusion distance
good blood supply / blood vessels
steep concentration gradient
counter current system
**insect ventilation
**muscular movement
contract/relax muscles to change vol of thorax and abdomen = causes pressure changes in tracheae and tracheoles, forcing air in/ drawing air out.
size of spiracle, changes / controlled
external gills in aquatic insects
small size / large SA:vol of insects, means
diffusion may be sufficient
**insect gas exchange
**gas / oxygen / CO2, diffuses along
tracheae
oxygen dissolves in water at tracheoles
diffuses into surrounding cells
many tracheoles so large surface area
spirals of chitin hold
tracheae open
