Extra/intracellular conc of Na⁺

Ex 140 mM

In 10 mM

Extra/intracellular conc of K⁺

Ex 4 mM

In 140 mM

Extra/intracellular conc of Ca²⁺

Ex 1 mM

In 50 NANOMOLES

Extra/intracellular conc of Cl^-

Ex 100 mM

In 10 mM

Bulk flow

mvt of solution due to change in hydrostatic pressure (hi to lo pressure)

primary fn in circulatory system

Diffusion

mvt of solutes due to random thermal mvt, results in net mvt high to low conc.

relationship between distance molecule must travel and time

x=multiplier of distance

time = x²

distances must be kept small to achieve rapid mvt of solutes

electrical migration

mvt of ions due to electric field

flux

net mvt of a substance

F=Quantity/T

F=Permability*Area*Conc Difference

factors affecting permeability

size, lipid solubility (dissolved gas like oxygen and carbon dioxide have high solubilities in lipids--primarily diffuse)

permeability of ion channels

number of channels, conductance (ions/second), open probability (fraction of channels open)

facilitated diffusion

no ATP needed, essentially speeds up diffusion

carriers and channels (specificity, saturation, competition)

channels are faster

active transport

ATP required, can work agains electrochemical or concentration gradient

primary active transport

ATPase/pumps/membrane transport proteins

Na⁺/K⁺ pump

1 ATP--> 3 Na+ out, 2 K+ in

Ca²⁺ pump

sequesters calcium ions within ER/SR of cells, released to initiate cellular processes (e.g. muscle contraction)

in cardiac muscle, moves Ca2+out of cytoplasm into extracellular flud

H⁺pump

basolateral membrane of parietal cells (stomach)-->HCl during digestion

kidney

secondary active transport

co/countertransport

coupling, mvt of one molecule with gradient requires binding of another molecule which can be moved against gradient

no direct use of ATP

osmolarity

concentration of dissolved particles

high osmolarity= low [h20], hi [solute]

iso/hypo/hyperosmotic

compare osmolarity of one solution to that of a reference solution

not to be confused with tonicity, which is a biological property depending on osmolarity and permeability, osmolarity is a physical property of solution, depending only on conc of solutes

steady state volume

ONLY determined by impermeant particles