Fish Exchange Flashcards
SA:V ratio?
small
impermeable outer surface
gases can’t diffuse through their skin
require a specialised gas exchange surface and transport system
Specialised exchange surface
gills
Circulatory system
moves blood around their bodies
Ventilation
gill irrigation
fish pump water over their gills inorder to perform gas exchange
Boyle’s Law
volume and pressure are inversely proportional
fluids (gases and liquids) move down the pressure gradient
Intake of Water
mouth opens bucal cavity floor lowers operculars closed increases volume decreases pressure water flows down pressure gradient and into the mouth
Release of water
mouth closes bucal cavity floor raises opercula open decreases volume increases pressure water flows down the pressure gradient and out of the fish via the operculum
Gill Lamellae
folds on each gill filament
increase surface area for diffusion
permeable membranes
lots of capillaries to increase blood flow
maintain diffusion gradient
thin flattened cells for a short diffusion pathway
Counter Current Flow
flow of water over the gill lamellae and flow of blood within them flow in OPPOSITE directions
Reason for counter current flow
so a diffusion gradient is maintained across the whole lamellae
equilibrium is not reached
Parallel flow
gases only diffuse until equilibrium is reached
diffusion gradient is not maintained across full lamellae
Permeable membrane
gill lamellae are permeable to oxygen and carbon dioxide
Movement of Environmental and Internal medium
ventilation movements push water over the gills in one direction
blood flows in the opposite direction
diffusion concentration gradient is maintained acroos entire length of lamellae
