osmoregulation 1 Flashcards
three homeostatic processes
osmotic regulation
ionic regulation
nitrogen excretion
osmotic regulation
osmotic pressure of body fluids
ionic regulation
concentration of specific ions
nitrogen excretion
excretion of end-products of protein metabolism
osmotic pressure is created by…
solutes
osmosis
diffusion of water
osmotic pressure
force associated with diffusion of water
osmolarity
ability of solution to induce water to diffuse across a membrane
-determined by total concentration of dissolved particles
(see pg 29-30)
-most cells are perfect osmometers
sea water’s % salinity
3.5% salinity/sea salts
hyperosmotic solution
loss/outflow of water to equalize osmotic pressure
-occurs in marine environment
hyposmotic solution
inflow of water to equalize osmotic pressure
-occurs more in freshwater environment
tonicity
-measure of osmotic pressure gradient of two solutions separated by a semipermeable membrane
(often used when describing the response of cells immersed in an external solution, ie. hyper/hypotonic)
osmoregulation overview
- animals must control extracellular environment
- individual cell control is expensive
- mostly rely on epithelial tissues to isolate cells from the external environment
- kidney is central to ion and water balance
- also rely on gills and digestive mucosa
useful terms: apical
side facing external environment/lumen
useful terms: basolateral
-side facing internally
interstitial (fluids)
small area between cells
solutions vs solutes vs solvents
solutions=solute+solvent
solutes=thing being dissolved
solvents=thing solute being dissolved into
ionic and osmotic challenges for marine environments
animals tend to gain salts and lose water
freshwater ionic and osmotic challenges
-animals tend to lose salts and gain water
terrestrial ionic and osmotic challenges
animals tend to lose water
importance of ionic and osmotic regulation
ion concentration can affect structure and function of macromolecules
-disrupts proper cellular function
cells exposed to osmotic gradients can shrink of swell
-can damage or destroy cell, cause disruptions in cell-cell communication
regulators vs conformers
reg=internal environment different from external and/or internal stays stable while external changes
conformers=internal conditions similar to external conditions even when external conditions change
ionoconformer
exert little control over ion profile within extracellular space
-exclusively found in marine animals, ie. many invertebrates
ionoregulator
- control ion profile of extracellular space
- ie. most vertebrates
osmoconformer
- internal and external osmolarity similar
- ie. marine invertebrates
osmoregulator
- osmolarity constant regardless of external environment
- ie. most vertebrates
regulation
- ability to cope with range of external salinities
- doesn’t tell you optimal level
- applies to both osmoconformers and regulators
stenohaline
tolerate only narrow ranges
euryhaline
tolerate wide ranges
eury/stenohaline osmoregulator vs conformer graph
- osmoconformer on a slope, while regulator close to parallel line
- eury wider range than steno in both cases
problems related to osmotic regulation
- all organisms require water
- freshwater regulators=excess water intake
- marine regulators=excess ion load
- terrestrial osmoregulators=dessication
sources of water
- drinking
- dietary water (not 100% efficient, must go through digestion and hydrolysis
- metabolic water (generated from oxidative phosphorylation)
classifying solutes by their effects on macromolecules
perturbing
compatible
counteracting
perturbing colutes
- disrupt macromolecular function
- Na+, K+, Cl-, SO4+, charged amino acids
compatible solutes
- little affect on macromolecular function
- polyols (glycerol, glucose) and uncharged amino acids
counteracting
- disruption function on their own, but counteract disruptive effects of other solutes when in combination
- ie. urea and TMAO
2 most common osmo/ionocomformers and regulators
Na+ and Cl-
cell volume
-solutes are moved in and out of extracellular fluid (ECF) to control cell volume, with water following solutes by osmosis
regulatory volume increase (RVI)
import of ions causing influx of water
-sodium, chlorine, and potassium diffusion channels
regulatory volume decrease (RVD)
expulsion of ions causing efflux of water
- potassium and chlorine diffusion channels
- calcium or sodium via atp pumps
facilitated diffusion protein types
channels (free diffusion) and permease (selective)
