Solute Transport

Question 1

Brownian motion

Answer 1

E required for simple diffusion

move down concentrtion gradient

Question 2

factors in simple diffusion

Answer 2

partition coefficient - how well substance moves into lipid from water (dx)

D- diffusion coefficent - how well moves when in the membrnae (inversely propotional to MW, viscosity of medium)

Question 3

Fick’s Law

Answer 3

flux (j)

Permeability coefficient x driving force

P = D x A x 1/X

molecules that cross certain area/second = flux

Question 4

basolateral membrane

Answer 4

faces blood (capillaires)

Question 5

apical membrane

Answer 5

faces lumen

Question 6

antiporter

Answer 6

2 ions in opp direction (simple diffusion)

Question 7

symporter

Answer 7

i.e. glucose and Na+

secondary active transport

co transport

Question 8

channel

Answer 8

has gate

Question 9

pore

Answer 9

has no gate (H2O)

Question 10

Na/K ATPase

Answer 10

primary active transport

requires energy to oppose concentration gradient

[Na] - higher onoutside

[K] -higher on inside

pump Na out and K in

requres ATP

on basolateral membrane of every epithelial cell

Question 11

paracellular transport

Answer 11

in tight junctions

mediated by claudins

Question 12

Na+-glucose transport

Answer 12

secondary active transport

Na/K transport pumps Na out wiht ATP (basolateral side)

Na+/glucose (SGLUT) pumps glucose in

Na+ gradient is potential energy

Glucose leaves through GLUT 2 - not dep on gradient/E = through basolateral side

Question 13

Amino Acids into cell

Answer 13

secondary active transport - also linked to Na+ gradient

Question 14

Carrier mediated transport

Answer 14

fasterthan diffusion

can saturate

acts as enzyme

diff from ion channels (which have gates)

Question 15

K+/H+

Answer 15

ATPase - responsible for gastric acid secretion

active

Question 16

Na+/H+

Answer 16

exchange

responsible for intracellular pH and Na exchange

Question 17

Cystinuria

Answer 17

for cysteine - transports Cystine in for reabsorption (apical membrane) - transporter

if mutations = urine has 100% of cystine - stones (poorly soluble)

SLCs

drink water or bowel as urater

Question 18

CDME

Answer 18

analog for cystine

slows crystal growth

Question 19

Water composition of humans

Answer 19

60% - varies based on muscle mass (less mucscle mass = less water)

muscle –> intracellular space

distribution –> blood volume (BP) and cell volume (cell function)

Question 20

water - intracell v extracell

Answer 20

2/3 intracellular

1/3 extracellular

Question 21

water - extracellular distribution

Answer 21

3/4 intracellular (between cells, vessels)

1/4 intravascular (plasma - 75% is in veins) )

Question 22

plasma composition

Answer 22

93% is water, 7% is proteins and lipids

Question 23

intracellular osmole

Answer 23

K

solute that keeps water in that compartment

Question 24

extracellular osmole

Answer 24

Na

Question 25

intravascular osmole

Answer 25

plasma proteins

Question 26

effective osmole

Answer 26

i.e. glucose in the absence of insulin

can’t cross any membrane! water always goes in that direction

Question 27

ineffective osmole

Answer 27

i.e. urea (except in kidney)

always movesacross membrane

Question 28

permeant solutes

Answer 28

can only lead to transient changes in volume

Question 29

impermeant solutes

Answer 29

can influence cell volume at steady state

Question 30

osmolarity

Answer 30

osmoles/L

same as osmolarity in dilute fluids

Question 31

osmotic coefficient

Answer 31

osmotic coefficient - if not perfectly ionized

i.e. .93 for NaCl

Question 32

iso-osmotic

Answer 32

same total number of particles

same osmolarity

1 M glucose, 1 M urea, .5 M NaCl

all solutes matter

Question 33

isotonic

Answer 33

same number of osmotically active particles

same osmotic pressure

.5 NaCl, .333 CaCl2, NOT 1 M urea

non penetrating solutes mater ONLY

Question 34

NS + D5W

Answer 34

roughly isoosmotic (same number of mosm/kg-water)

NOT isotonic: due to effects of insulin - glucose moves into cells and it is NOT an effective osmole under that coldition (NaCl is effectively extracellular due to Na/K-ATPase)

Question 35

hypotonic solution

Answer 35

if put cell in it will swell/yse

pressure ECF < presure ICF

Question 36

isotonic solution

Answer 36

cells stay the same

P of ECF = P of ICF

Question 37

hypertonic solution

Answer 37

cells will shrink

P of ECF > P of ICF

Question 38

Cell response in hypertonic ECF

Answer 38

usually cell will shrink and water will leave

cell pumps salts in (NKCC) - Na+, Cl- x2, K+ so not as much water will leave

Question 39

cell response in hypotonic solution

Answer 39

cell will swell

swelling activates K chanels and K diffuses OUT down electrochem gradient

osmoles leave cell and water follows

Question 40

paracellular transport

Answer 40

passive but selective variable and regulated

through tight junctions

H2O through paracellular space - in response to osmolarity - Na leaves and H2O neaves

Question 41

Leaky epihelia

Answer 41

large volume reapsorption - jejumum, proximal tubule

Question 42

tight epithelia

Answer 42

for concentrtion excreta - collon and collecting duct

Question 43

ECF volume

Answer 43

determined by total body Na+ content

Question 44

osmolarity

Answer 44

determined by total body water content

Question 45

ECF Na+ content

Answer 45

in mmoles

= [Na+] x ECF vol (L)

= osmolality/2 x ECF vol ()

Question 46

total body osmoles

Answer 46

[osm] X TBW (L)