osmoregulation and excretion Flashcards
what does intracellular environment effect
organic molecule formation
what is protein function (e.g enzymes) affected by
ion concentration
when is protein function optimal
within a narrow range of inorganic ion concentration
what are the three compartments water flows between
intracellular, interstitial fluid, blood plasma (inter and blood=extracellular)
what is the make up composition of humans
60% water and 40% bone, protein, lipids
what does osmoregulatory systems regulate
water/solutes in blood, secondarily in intentional fluids
how can cells react to there environment out side
they have some ability to alter their cell volume
how do most cells regulate their intracellular ion compsition
using ATP
most animal cells are…
water permeable
because animal cells are water permeable what does this mean for what they can control
they can control there ionic differences across the cell membrane but not osmotic differences
what are the two main routes of transport epithelial cells use
-transcellular transport
-paracellular transport
what is transcellular transport
movement through the cell across membranes
what is paracellular transport
movement between cells
leaky vs tight epithelia
what is epithelium
layer of cells
what are some types of transporters
-Na+K+ATPase, Ca2+-ATPase
-ion channels (Cl-, K+,Na+,Ca2+)
-electroneutral cotransporters (-paired with+)
-electroneutral exchangers
how does water move
from low solute concentration (high water potential) to high solute concentration (low water potential)–>osmotic graident
what s osmolarity
the measure of solute concentration (number of osmoles per liter)
-1 mol glucose=1 osmole
-1 mol of NaCl=2 osmole
how do most cells respond to swelling or shrinkage
by activating specific membrane transport and/or metabolic processes that serve to return cell volume to its normal resting state
how sensitive are volume sensing mechanisms
can sense and respond to volume changes of 3%
whats RVI
-regulatory volume increase when the cell gains solute if the cell gets too small
what is RVD
regulatory volume decrease when the cell looses solute if cell gets to big
what are the transporters involved with RVI
-Cl-HCO3 exchanger
-Na-H exchanger
-Na-K-Cl cotransporter
what are the transporters involves with RVD
-K-Cl cotransporters
-K+ or Cl- channels
what are the three homestatic processes
-ionic regulation
-volume regulation
-osmotic regulation
what is ionic regulation
concentrations of specific ions
what is volume regulation
total amount of water in a body fluid
what is osmotic regulation
osmotic pressure of body fluids
what is osmoconformers
-strategy animals evolved to deal with osmotic stress
-it means body fluids and cells are equal in osmotic pressure to the environment
-mainly found in ocean where osmolarity averages 1000 mOsm
what are osmoregulators
-strategy animals evolved to deal with osmotic stress
-osmotic pressure of body fluids is homeostatically regulated and usually differrent from the external environment
what are the different stratigies animals have evolved to maintain homeostasis
osmoconformation and osmoregulation
how does osmoregulation in fresh water fish work, what are some consequences of being fresh water and how are they dealt with
-fresh water has a mOsm of <5
-fish has a 300 mOsm
-FW wish lose salt and gain water
-water is absorbed through skin and gills
-salt is lost via facies
-water and some salts are lost via urine
-they obtain salts via chloride cells in gills and with food (using ATP to pump in)
-fish dont need to drink
how does osmoregulation in marine water fish work, what are some consequences of being fresh water and how are they dealt with
-sea water has mOsm of 1000
-fish body has mOsm of 400
-they loose water through gills and skin
-salt loss via facies, salt and little water loss via scant urine
-gain water and salts by swallowing seawater and food
-removes salts via chloride cells in gills
-they drink sea water to obtain water but it also takes up more salt
-retaining water and getting rid of salts in the goal
what is osmoconformers a common strategy in
by marine invertabrates
what takes more energy osmoconforming or osmoregulation
osmoconforming is energetically less expensive then osmoreg
can osmoregulators cope with changes in extracellular osmolarity and ion concentration
no
what maintains a strict extracellular osmotic homeostatasis
osmoregulators
what has a high degree of cellular osmostic tolerance
osmoconformers
in osmoconfromers how can cells cope with extracellular osmolarities
by increasing intracellular osmolarities with compatible osmolytes—>maintaining cell volume
what is the molarity of extra cellular fluid in osmoconformers and what solute is most present
simular to sea water (1000mOsm), dominated by NaCl
in osmo conformers what is the the difference of pressure in ICF and ECF
they have the same osmotic pressure with universal solutes and organic osmolytes
what are some common organic osmolytes
carbohydrates, free amino acids, methylamines, urea, and methylsulfonium solutes
how do organic osmolytes effect macromolecules
they dont disturb then some even stabilize then against denaturing force of others
what are solutes classified based off of
by their effects on macrmolecules
what are perturbing solutes
-they disrupt macromolecular functions
-Na+, K+, Cl-, SO4+, charges amino acids
what are compatible solutes
-little effect on macromolecular function
-polyols (glycerol, glucose, and uncharged amino acids
what are counteracting solutes
-disrupt macromolecular finctions on their own
-counteract disruptive effects of other solutes when employed in combination
what do cartilaginous fish do to increase their tissue osmolarity
-they use urea as an osmolyte
-helps prevent water loss in marine environment
-ureas perturbing effects counteracted by methylamines (e.g TMAO)
what are the two types of osmoconformers
-stenohaline
-euryhaline
what are stenohaline osmoconformers
-they are restricted to a narrow range of salinity
-they cant regulate their osmolytes to compensate
-cant tolerate changes
-stay in the ocean
what are euryhaline osmoconformers
-they are tolerant of changes in salinity
-sucessful in intertdal zones
-regulate organic osmolytes in their cell
in stenohaline bull sharks what happened when they went from salt water to fresh water
-20% reduced Na, Cl
-50% reduced urea
-body fluids still had double osmolarity than fresh water fish
-massive influx of water
-massive urine production (20x more then in salt water)
what else are osmoregulatory organs involves with
nitrogen waste excretion
what is the problem with N waste
-metabolism of proteins and nucleic acids
-produces ammonia (toxic)
-accumulation of NH3 would lead to death (must be excreted)
-NH3 is very soluble–> excretion would require large amounts of water
-animals have developed different strategies depending on water avalibility
what are some N waste strategies and what are they seen in
NH3- seen in teleosts, larval amphibians, aquatic invertebrates
urea- seen in mammals, sharks, rays, turtles, adult amphibians
uric acid- seen in lizards, snakes, birds, insects
what is the most toxic to least toxic and least energy to produce to most energy to produce for N waste in animals
ammonia, urea, uric acid
what are some characteristics of ammonia
-very soluble in water but toxic at low concentrations
-easily permeates membranes
what are ammoniotelic animals
animals that excrete ammonia
how to invertabrates release ammonia
they diffuse it out of the body surface into surrounding water