Osmosis

what is the trend of water content as % of total body weight by age and sex?

decreases as age increases decreases more rapidly for females

what is the intracellular fluid?

2/3 of the total body volume has a net (-) charge and a slight excess of anions

what is the extracellular fluid?

1/3 of the total body water volume consists of interstitial fluid and blood plasma has a net (+) charge and a slight excess of cations

what is the interstitial fluid?

fluid that lies between the circulatory system and the cells

what are the 2 body fluid compartments?

extracellular fluid (ECF) and intracellular fluid (ICF) that are in osmotic equilibrium and chemical and electrical disequilibrium

what must material cross when moving between the ECF and ICF?

the cell membrane/selectively permeable barrier

what must substances cross when moving between the plasma and interstitial fluid?

the leaky exchange epithelium of the capillary wall

what is osmosis?

the movement of water across a selectively permeable membrane in response to a solute [ ] gradient

what are aquaporins?

special protein channels used for osmosis

how does water move during osmosis?

from areas of low [solute] to areas of high [solute] in an attempt to equalize the [solute] on both sides

what is osmotic pressure?

the minimum pressure that stops the osmosis

what does isosmotic mean?

same osmolarity as surroundings

what does hyperosmotic mean?

increased osmolarity than surroundings

what does hypoosmotic mean?

lower osmolarity than surroundings

what is osmolarity?

measure of the # of particles (osmol/L) takes into account dissociation of the molecules in solution

what is tonicity?

takes into account both the relative solute [ ] and the cell membrane's permeability to those solutes

what does isotonic mean?

equal, no change

what does hypertonic mean?

higher osmolarity (more particles)

what does hypotonic mean?

lower osmolarity (fewer particles)

what is bulk flow?

diffusion of gases and liquids using pressure and [ ] gradients

what are the properties of diffusion?

passive high [ ] to low [ ]: chemical gradients in equilibrium rapid over short distances directly related to temperature inversely related to molecular weight and size in open systems or across a partition ions move according to electrochemical gradient

what do channel proteins do?

create a water-filled pore

what are the structures of membrane proteins?

integral proteins: within the membrane peripheral protein: on the membrane

what are the function of membrane proteins?

membrane transport, structure, membrane receptors that activate enzymes

what different channels are there?

water: aquaporins ion: open, gated (mechanical, chemical, voltage)

what are the different carriers for the # of molecules transported?

uniport, symport, antiport

what is facilitated diffusion?

uses carrier proteins no energy input, down a [ ] gradient conformational change

what is active transport?

uses carrier proteins energy input, against a [ ] gradient direct transport uses ATP indirect transport uses the potential energy of another molecule involves competition and saturation

what happens to ligand binding sites when the protein conformation changes?

they change affinity

what is transport saturation?

transport can reach a maximum rate when all the carrier binding sites are filled with substrate transport rate is proportional to [substrate] until the carriers are saturated

what is the electrochemical gradient?

the combination of the electrical gradient at the plasma membrane and the chemical concentration gradient of the specific ion

what does the changes in ion permeability that change the membrane potential depend on?

[ions] across the membrane permeability of the membrane to ions (depolarization, repolarization, hyperpolarization)

what is the resting membrane potential difference?

the steady state due mostly to K+ in actual cells potential energy stored in the electrochemical gradient difference in electric charges inside and outside of the cell can change over time

what results in changes in the membrane potential?

if the membrane potential becomes less (-) than the resting potential, the cell depolarizes if the membrane potential becomes more (-), the cell hyperpolarizes