Hypo-osmotic - Hypo-ionic Regulation
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1000. e.g. Uca, Artemia. ECF osmolarity (mOsm). marine teleosts. 1000. 0. Medium osmolarity (mOsm). Hypo-osmotic - Hypo-ionic Regulation. Crustacea:. Uca - hemolymph Na = 447 mM in 175% sw (~ 800 mM). Artemia - hemolymph Na = 300 mM in as much as 4-5 M NaCl !!!. H 2 O ions. - PowerPoint PPT Presentation
Transcript of Hypo-osmotic - Hypo-ionic Regulation
Hypo-osmotic - Hypo-ionic Regulation
Medium osmolarity (mOsm)
0 1000
1000E
CF
osm
olar
ity (
mO
sm)
e.g. Uca, Artemia
marine teleosts
Crustacea:
• Uca - hemolymph Na = 447 mM in175% sw (~ 800 mM)
• Artemia - hemolymph Na = 300 mMin as much as 4-5 M NaCl !!!
500 mM NaCl1000 mOsm
200 mM NaCl400 mOsm
H2O ion(s)
Problems:• osmotic water loss• diffusive salt gain
H2Oions
Solutions:• drink sea water
• ion uptake by gut• active salt extrusion
Marine Teleost
ant. post.mM
Fluid absorption across teleost gut:NO ACTIVE TRANSPORT OF H2O!
Must move ions and cause H2O to move by osmosis
s.w.Na = 450K = 9Cl = 520
Blood:
Na = 200K = 4Cl = 190
Na = 100K = 6Cl = 90
Na = 20K = 0.8Cl = 50
ions H2O
>95% of salts absorbed
~75% of H2Oabsorbed
lumen of gut
blood (serosa)
Cl-
HCO3-
ATP ADP+ Pi
Cl-
H+
Na+ATP
ADP+ Pi
Na+
K+
Na+Cl-
CC - mitochondria-rich chloride cellAC - accessory cell, PC - pavement cell
From Evans et al. (1999) J. Exp. Zool. 283: 641-652.
Apical pit of chloride cell on surfaceof gill lamella
From Evans et al. (1999) J. Exp. Zool. 283: 641-652.
Gill epithelial cell Blood
Isosmotic - Hypo-ionic Regulation
mMNa Cl TMAO + urea mOsm
Sea Water 450 500 0 1000
Hagfish Plasma 549 550 0 1150
Teleost Plasma 160 200 0 400
Elasmo. Plasma 290 300 350-400 1000
S.W.500 mM NaCl1000 mOsm
300 mM NaCl1000 mOsm
ion(s)Problem:Diffusive salt gain
Solution:Active salt excretion
Elasmobranchs retain nitrogenouscompounds as osmotic effectors:
H2N C = O
H2Nurea
CH3
H3C N = O
CH3
trimethylamine oxide(TMAO)
mMNa Cl TMAO + urea mOsm
Sea Water 450 500 0 1000
Plasma 250 250 420 1000
Urine 250 250 110 800
Rectal gland fluid 500 500 20 1000
Urea and TMAO are reabsorbed from theurine.
Salt is excreted via rectal gland and chloridecells in the gills.
Hyperosmotic-Hyperionic Regulation
Medium osmolarity (mOsm)
0 1000
1000E
CF
osm
olar
ity (
mO
sm)
e.g. freshwater fish &crustaceans
e.g. estuarinecrustaceans
150 mM NaCl300 mOsm
2 mM NaCl5 mOsm
H2O ion(s)
Problems:• osmotic water gain• diffusive salt loss
Freshwater crayfish, Astacus
H2Oions
antennalgland
Solutions:• produce copious urine
• urinary salt loss • decrease permeability• active ion uptake
NaCl
Na+ Cl-
Freshwater Fish (Teleost)
Voluminous, dilute urine
Don’t drink the water
Water Gill Epithelium
