BSC 2011C Lecture Notes - Lecture 23: Trimethylamine N-Oxide, Chondrichthyes, Osmoregulation
Document Summary
All animals require homeostasis of body fluids in terms of water gain/loss, and solute balance. All animals must deal with toxic ammonia that builds up as a metabolic waste product: requiring excretion. Osmosis: passive transport that flows down the concentration gradient of water across a semi- Live in stable osmotic environments and require little movement of water. Osmoconformer: maintain the same osmolarity as the environment (isosmotic) Osmoregulator: control internal osmolarity independently of the environment. Regulation allows broader environments, e. g. freshwater, terrestrial: in hypo-osmotic environment: must discharge water, in hyper-osmotic environment: must take in water. Stenohaline ( steno =narrow; haline =salt): intolerant of large changes in external salinity. Euryhaline ( eury =broad): tolerant of large changes in external salinity. They maintain high levels of toxic urea (nitrogenous waste product) but have trimethylamine oxide (tmao) to protect from urea. They could be considered osmoconformers but do not have active removal of water by kidneys.
