Ion and Water Balance 1 Flashcards
animal environment
- external world outside the whole animal
cell environment (2)
- extracellular fluid for a cell
- plasma and interstitial fluid
intracellular enzyme environment (2)
- cytoplasm
- intracellular fluid
how do animals control ion and water balance in internal/external environments
- use different combinations of tissues
what is the general combination of tissues used to control ion/water balance in animals (5)
- mucus
- apical membrane
- basolateral membrane surrounded by interstitial fluid
- endothelium
- plasma and blood cells
homeostatic processes (3)
- osmotic regulation
- ionic regulation
- nitrogenous waste excretion
homeostatic processes: osmotic regulation
- osmotic pressure of body fluids
homeostatic processes: ionic regulation
- concentrations of specific ions
homeostatic processes: nitrogenous waste excretion
- excretion of end-products of protein metabolism
how do solutes move through water
- by diffusion
rate of diffusion
dQs/dt
Fick Equation for the rate of diffusion
dQs/dt = Ds x A x (dC/dX)
diffusion coefficient
- takes into account the size of the molecule and hydration shell
Ds
- diffusion coefficient
A
- diffusion area
dC/dX (2)
- size of the concentration gradient
- X is the distance
what does the direction of diffusion depend on
- the concentration gradient
what forces will affect the movement of water across a semipermeable membrane (2)
- osmotic pressure pushing water toward an area of higher solute concentration
- gravity pushing water down
hyperosmotic
- solution with higher osmolarity
hypoosmotic
- solution with lower osmolarity
isosmotic
- when the osmolarities of two solutions are the same
what kind of solution does water diffuse from/into
- water diffuses from a hypoosmotic solution to a hyperosmotic solution
tonicity
- the affect of a solution on cell volume
hypertonic solution
- solution outside the cell has higher concentrations of solute
hypotonic solution
- solution outside the cell has lower concentrations of solute
isotonic solution
- solution outside the cell has the same concentrations of solute as inside the cell
how does the cell behave in hypertonic solutions (2)
- cell shrinks
- water leaves the cell by osmosis
how does the cell behave in hypotonic solutions (2)
- cell swells
- water enters the cell by osmosis
how does the cell behave in isotonic solutions (2)
- cell neither shrinks nor swells
- no net osmosis
what can occur when RBCs are in hypertonic solutions (2)
- cell shrinks
- Hb can crystallize due to high concentrations inside RBC
why is it important to regulate cell osmolarity (2)
- increased intracellular osmolarity can directly interfere with cellular processes
- result in water movement across membrane, changing cell volume
what cellular processes can be interfered during increased intracellular osmolarity (2)
- protein-protein interactions
- cellular fluidity for diffusion
what cell implications occur after moderate swelling
- disruption of membrane
what cell implications occur after excessive swelling
- cell lysis (pops)
what cell implications occur after excessive cell shrinking
- macromolecular crowding
what can macromolecular crowding result in
- less efficient and impaired cell functioning
how do cells control their volume (2)
- transport solutes in and out of extracelullar fluid (ECF)
- water follows solutes by osmosis
how do animals regulate their cells’ volumes (2)
- regulate the composition of the ECF
- provides cells with a constant external solution that allows them to maintain appropriate cell volume
what structures do animals use to regulate their ECF (2)
- mammals use kidneys
- fish use gills
what ions do cell move to regulate ions/water when ECF isn’t constant (4)
- sodium (Na+)
- potassium (K+)
- chloride (Cl-)
- calcium (Ca2+)
what transporters are used to regulate sodium (2)
- 3 Na+/2 K+ ATPase
- Na+/H+ exchanger
what transporters are used to regulate potassium
- 3 Na+/2 K+ ATPase
what transporters are used to regulate chloride
- generally distributed passively according to the Goldman equation
what transporters are used to regulate calcium (2)
- Na+/Ca+ antiporter
- Ca2+ ATPase
what is the NKCC transporter
- Na+/K+/2Cl- cotransporter
active increase of cell volume by import of ion
- regulatory volume increase (RVI)
regulatory volume increase process (2)
- cells actively import ions
- water follows ions passively
RVI transporters (4)
- usually achieved by activating NKCC cotransporter
- Na+ channels
- Cl- channels
- Na+/H+ exchangers
active decrease of cell volume by exporting ions
- regulatory volume decrease (RVD)
regulatory volume decrease process (2)
- cells actively export ions
- water follows ions passively
what is the usual mechanism of RVD (5)
- opening of K+ channels
- K+ leaves cell down electrochemical gradient
- water follows passively
- inside becomes too negative
- Cl- channels open and Cl- leaves due to hyperpolarizing effects of K+ movement
RVD transporters
- K+ channels
- Cl- channels
- K+/Cl- co-transporters
- Na+/Ca2+ exchanger
- Ca2+ ATPase
- Na+/K+ ATPase
how is water regulated for cell volume
- passively regulated in response to changes in ions and osmolarity
porins
- like ion channels, but for transport of larger molecules
aquaporins
- membrane transporters specific to water molecules
ionic and osmotic challenges: marine environments (2)
- gain of salts
- loss of water
ionic and osmotic challenges: freshwater environments (2)
- loss of salts
- gain of water
ionic and osmotic challenges: terrestrial environments
- loss of water
ionic and osmotic challenges: movement between environments
- ability to alter homeostatic processes to meet demands of each environment
what are the strategies used to meet ionic challenges (4)
- ionoconformer
- ionoregulator
- osmoconformer
- osmoregulator
ionoconformers
- exert little control over ion profile within extracellular space
what type of animals are ionoconformers
- exclusively found in marine animals
ionoregulator
- control ion profile of extracellular space
what type of animals are ionoregulators
- most vertebrates
osmolarity of surroundings vs plasma: ionoconformer + osmoconformer (2)
- same osmolarity
- same ion concentrations/composition
osmolarity of surroundings vs plasma: ionoregulator + osmoconformer (2)
- same osmolarity
- different ion concentrations/composition
osmolarity of surroundings vs plasma: ionoregulator + osmoregulatory (2)
- different osmolarity
- different ion concentrations/composition
osmoregulator
- osmolarity is constant regardless of external environment
what types of animals are osmoregulators
- most vertebrates
osmoconformer
- internal and external osmolarity are similar
what types of animals are osmoregulators
- marine invertebrates
what terms describe the abilities of animals to cope with external salinities (2)
- stenohaline
- euryhaline
stenohaline
- can tolerate only narrow range of salinities
euryhaline
- can tolerate wide range of salinities
euryhaline osmoconformer
- osmolarity can decrease/increase in parallel with water until death
stenohaline osmoconformer
- dies after minimal osmotic disruptions
euryhaline osmoregulator
- maintains a nearly constant internal state throughout various major osmolarity changes, but eventually succumbs
stenohaline osmoregulator
- maintains internal osmolarity over narrow range of external osmolarities
