osmoregulation 1 Flashcards
osmolarity
measure of solutes/liter of water
mOsm/L
osmotic pressure
movement of water from high concentration (low osmolarity) to low concentration (high osmolarity)
membrane permeability
dictated by the presence of specific channels within membrane - water soluble solutes
aquaporin channel
integral membrane channel
specifically transports water but not solutes
expressed in all animals
channel evolution
simple invertebrates - voltage-gated enzyme activity (no pore)
invertebrates - voltage-gated proton channel (no pore)
vertebrates - channels with pores, allowing movement of ions
Na/K ATPase
most common transporter
osmoreceptors
change in osmolarity compared to interstitial fluid and blood, results in changes in cell shape and size
early hydrosphere
low pH dissolved rocks
presence of phytoplankton changes chemistry; formed oxides and precipitates into sediments
osmoconformers (OC)
internal osmolarity conforms to external osmolarity (not specific solutes)
less energy cost
osmoregulators (OR)
internal osmolarity is constant even when external osmolarity changes
high energy costs
complex organs
euryhaline animals
able to adapt to changing water osmolarity
estuaries, coastal regions
stenohaline animals
unable to adapt to changing water osmolarity
open ocean and freshwater lakes and rivers
osmoregulatory organ requirements
direct access to blood
blood pressure
size specific filtration barrier
reabsorption and secretion pathways
development of waste and storage center
membrane transporters
nephron - functional unit
size-specific filtration barrier
glomerulus - site of filtration and start of nephron
proximal convoluted tubule
extensive reabsorption of water and solutes
