Lecture 11: Water and Salt Physiology EXAM 2
in freshwater fish, chloride cells
(mitochondria-rich cells) pump ions in the blood across the gill epithelium and the kidneys excrete copious, dilute urine. this causes a metabolic waste product (CO2) and excess H+ are exchanged for much needed ions
seawater fish diagram
-NaCl is excreted through gills -NaCl foes in and H2O goes out -Mg, So4 excreted
counteracting solute effects
-effects of one osmolyte add to the effects of another -can offset damaging effects of one osmolyte acting alone
water and salt exchanges in freshwater
-hyperosmotic to ambient water -salt loss by diffusion -water uptake by osmosis -large amounts of urine -active uptake of Na+ and Cl- through gills
freshwater fish diagram
-intake of NaCl through gills -H2O goes in and NaCl goes out -H2O also excreted
how do animals regulate the composition and volume of their body fluids?
-ion regulation -volume regulation -osmotic regulation (U/P ratio)
water and salt exchange in seawater
-salt gain by diffusion -water loss by osmosis -salts and waters ingested -small amounts of urine
intake + metabolic production - output
= 0
in marine elasmobranch, ICF has high concentration of
K+, TMAO, glycine betaine, and urea
in marine invertebrates, ECF has
Na+, Cl-
in marine elasmobranch, ECF has a high concentration of
Na+, Cl-, TMAO, urea
organic osmolyte
any solute that exerts a sufficiently large effect on the osmotic pressure of body fluid
osmotic conformer
blood osmotic pressure will equal the osmotic pressure of the environmental water
how are kidneys organs of blood regulation
by removing salts, water, and other solutes from the plasma in controlled ways
xeric animals
can live in dry, water-poor environment (mammals, reptiles, insects, arachnids) -low integumentary H2O permeability due to integumentary lipids
metabolic water gain
food, drink, metabolsim
in marine invertebrates, ICF has
free amino acids, some glycine betaine, TMAO, K+, Cl-, Na+
isosmotic
having the same osmotic pressure
all freshwater animals are classified as
hyper osmotic regulators (blood is more concentrated than freshwater)
bony fishes are _____ to freshwater
hyperosmotic
freshwater animals are ______ to their environment
hyperosmotic
bony fishes are ______ to seawater
hyposmotic
in land animals, there is low integumentary water loss due to
integumentary lipids
elasmobranchs and invertebrates are approximately _____ with seawarer
isosmotic
most marine animals are nearly _____ with seawater
isosmotic
U/P = 1
isosmotic urine
properties of enzymes are usually less or more affected by organic osmolytes than by inorganic ions?
less affected
integument has
low water and ion permeability
osmotic regulation
maintenance of a constant or near constant osmotic pressure in the blood plasma
what' does TMAO do in sharks?
offsets damaging effects of urea
intracellular osmotic concentration is raised with
organic osmolytes
salt glands in birds and non-avian reptiles
provide external ion and osmoregulation
humidic animals
restricted to humid, water rich environments (slugs, amphibians, crabs earth worms) - have high integumentary H2O permability
water loss
skin, lungs, urine, feces
osmolarity of urine compared to ECF
urine has much lower osmolarity
