Osmoregulation Flashcards
How do salmon adapt to alternate between hyperosmotic and hypoostomic conditions?
Acclimatization regulation coupled with an anticipation mechanism; in the ocean, where they are hypo-osmotic, cortisol triggers the growth of seawater-type chloride cells in gills, which reverses te direction of ion transport and increases Na/K ATPase activity; in freshwater where they are hyperosmotic, prolactin stimulates freewater-type chloride cells, reversing the direction of ion transport
Describe the regulation of salt glands in birds
The hypothalamic osmoreceptor responds to a high blood osmolarity; through the parasympathetic nervous system, the pituitary gland is activated and then activates the adrenal gland to release corticosterone which will activate the salt gland; as well, high blood osmolarity causes teh heart to release an atrial natriuretic peptide which also stimulates the salt gland; the kidneys are shut down to conserve water; teh salt gland releases solutions that are twice as concentrated as the water taken in
How do diff types of cations and anions affect protein function?
Weakly hydrated cations, or strongly hydrated anions, cause protein to be more stable and clump together–decreases de taurine and solubility
Strongly hydrated cations, or weakly hydrated anions, cause solubility to increase, more unstable, more denaturation
Conc of K inside the cell?
100-150mM, above 180 it inhibits protein synthesis
Remember that ATP cannot move ions, but it can move water
Ye
Osmolarity and osmolality
Number of osmoles per litre; osmoles/kg
Cell volume regulation–shrinking and swelling
Shrink–pump ions in so water will move in, causing it to go back to normal
Swell–pump ions out, causes water to leave
Problem with gain or loss of ions during volume regulation?
Great changes in ion concentration can affect protein function in the long run; this mecha is. Is only good for a slight change in cell volume
Definition of osmoregulatora
Maintain a constant extracellular osmolality and ion comp
Strict extracellular osmotic homeostasis
Cells and tissues cannot cope with changes in extracellular osmolarity and ion comp
Osmoconformers
High degree of cellular osmotic tolerance
Cells and tissues have the control mechs and maintain intracellular osmolarities with compatible osmolytes
Osmoconformers ECF is isoosmotic with the environment, while the intracellular fluid maintains a constant osmolarity
Ye
Advantage of Osmoconformers?
Less energetically expensive
Osmoregulatory systems depend on what?
Transporting epithelia which offers active ion transport
How to freshwater fish maintain ECF?
Active uptake of ions across gills and skin; hypotonic fluid excretion by kidneys or other structures; lower internal osmolarities; low permeability of integuement
Salt glands contain active NaCl transport
Ye
