GAS EXCHANGE in ANIMALS aka respiration Respiration involves

GAS EXCHANGE in ANIMALS aka respiration • Respiration involves the diffusion of O 2/CO 2 across membranes I had to delete some graphics to keep this under 5 mb, sorry • CM requires water to be stable (no bonds between phospholipids) • Therefore, respiratory surfaces are wet : gills, lungs, skin, etc.

FICK’S LAW: Rate (R) of diffusion determined by: Concentration gradient Distance of diffusion Surface area

GILLS: External nudibranch salamander larvae

GILLS: Internal In osteichthyes, covered by the operculum Not so in chondrichthyes

Water must flow across gills continuously, via swimming, or pumping of operculum wat er bloo d Counter-current flow of blood/water maximizes diffusion

On land, respiratory structures need support & protection from drying out Spiracle/tr acheal system of Arthropod a

LUNGS employ smaller and smaller tubes Reduces water loss from surface Gases move in/out based on differences in air pressure

Amphibians create high pressure in buccal cavity, forcing air into lungs More common is the opposite – low (negative) pressure in lung cavity causes air to rush in ribcage raised, diaphragm drops, volume increases, pressure decreases

Alveoli are the site of gas exchange with the blood

O 2 has low solubility (3 m. L/L) GAS TRANSPORT Solution? Bind it to Fecontaining hemoglobin in RBC (200 m. L/L)

oxyhemoglobin deoxyhemoglobin