osmoreglation and ion regulation Flashcards
what 2 types of gradient can result in diffusion
ionic and concentration
are cations positively or negatively charged
positive
what is osmosis
movement of a solvent (water) passively across a semi-permeable membrane
what is osmolarity
concentration of all particles in a solution
how is osmolarity measured
osmols / Litre
what is the osmolarity of 1 mol/L CaCl2
= 1 Osm/L Ca+ and 2 Osm/L of Cl-
= 3 Osm/L
what is tonicity
solute concentration that directly affects water movemnt by osmosis
what particles does tonicity refer to
only solute particles that cannot cross the membrane
what happens if a normal cell is placed in to a hypotonic solution
water diffuses into cell causing it to swell
what happens when a cell is placed in a hypotonic solution for a long duration
hemolysis - burst
what occurs if a cell is continuously in a hypertonic solution
crenation
what molecules are transported via facilitated diffusion
polar molecules and larger ions
what are the transporters used in secondary active transport
symporter and antiporter
how do molecules move in secondary active transport
ion pumps create elctrochemical gradient driving secondary movement
what transporter increases the rate of water movement
aquaporin
what 2 things often control ion channels
ligands or voltage
name a well known use of active transport
Na+ / K+
sodium potassium pumps
2 osmotic challenges
ingestion and excretion,
external environment
what is an osmoconformer
body fluid and cellular osmolarity similar to that of external environment
what types of animal are osmoconformers
invertebrates and some marine vertebrates
how do elasmobranchs maintain extracellular fluid osmolarity
urea and NaCl secretion
what is an osmoregulator
body fluid osmolarity is homeostatically regulated different to that of external environment
what are the boundaries of osmolarity for an osmoregulator
290 - 400 mOsm / L
in a hyper-osmoregulator, does the body fluid or external media have higher osmolarity
body fluid is higher
what does euryhaline mean
they tolerate a large range of salinities
what does stenohaline mean
only tolerate a narrow range of salinities
what type of cell is used for epithelial transport in teleosts
ionocytes - mitochondria rich cells
3 ways freshwater teleosts fight against water gain and salt loss
produce alot of dilute urine, reabsorbing urine salts,
gain salts from diet,
active uptake of salts from water via gills
how do freshwater teleosts carry out active salt uptake
Na+ / K+ ATPase lowers cellular NA+
H+ ATPase creates local membrane potential driving NA+ uptake
Cl- uptake by apical HCO3- exchange
Cl- enters blood against conc gradient
4 ways marine teleosts defend themselves against water loss and salt gain
low urine flow rates,
drink seawater to replace lost volume and active water uptake in gut,
don’t reduce permeability,
active excretion of salts via gills
explain the process of active salt excretion in marine teleosts
Na+ / K+ ATPase lowers cellular Na+ and increases basolateral Na+
Na+ gradient drives Cl- entry via co-transporter
Cl- excreted via apical channels#
Na+ excreted by passive paracellular diffusion due to electrochemical gradient
K+ ions must recycle
explain the process of active water uptake in marine teleosts
oesophagus and stomach - passive NaCl diffusion from seawater to blood
intestine - active salt uptake followed by water uptake
what teleosts are euryhaline and why
salmonids and eels
have freshwater to saltwater migrations
what is the name for migration from freshwater to saltwater
smoltification
what changes occur in a salmonid when undergoing smoltification
acclimation induced by growth hormone and cortisol
apical proton pump is down regulated
proliferation of gill ionocytes
increased Na+ / K+ ATPase activity
increase NaCl secretion
silvering up and changes in body shape
how do marine birds and reptiles cope with drinking sea water
secrete salt into salt gland
