Osmosis

Question 1

aquaporins

Answer 1

family of membrane proteins forming channels through which water can diffuse
type and number differ in different membranes -> permeability

Question 2

aquaporins in the kidney

Answer 2

epithelial cells contain numerous aquaporins that can be increased or decreased in number depending on the water balance at the time

Question 3

osmosis

Answer 3

net diffusion of water across a membrane

Question 4

addition of solute to water

Answer 4

decreases the concentration of water to less than pure water

Question 5

concentration of water in pure water

Answer 5

55.5M

Question 6

factors affecting the degree to which water concentration is decreased by addition of a solute

Answer 6

number of particles of solute in solution

not on chemical nature of solute

Question 7

ionising molecules in solution

Answer 7

decreases water concentration in proportion to the number of ions formed

Question 8

osmolarity

Answer 8

total solute concentration of a solution

Question 9

osmol

Answer 9

1 mol of solute particles

Question 10

osmolarity and water concentration

Answer 10

the higher the osmolarity, the lower the water concentration

Question 11

membrane permeable to water but impermeable to solute

Answer 11

same concentration of water and solute will be reached at equilibrium as before
change in volumes of the compartments

Question 12

semipermeable membrane

Answer 12

membrane permeable to water but impermeable to solute

Question 13

osmotic pressure

Answer 13

pressure that must be applied to the solution to prevent net flow of water into it

Question 14

osmolarity and osmotic pressure

Answer 14

greater the osmolarity, the greater the osmotic pressure

Question 15

nonpenetrating solutes

Answer 15

substances that cannot cross the plasma membrane - don’t penetrate through the lipid bilayer

Question 16

examples of nonpenetrating solutes

Answer 16

Na+ and Cl- outside the cell, and K+ and other organic solutes inside the cell

Question 17

osmolarity of ECF

Answer 17

285 - 300 mOsm

Question 18

osmolarities at equilibrium

Answer 18

ECF and ICF are equal

Question 19

changes in osmolarity of ECF

Answer 19

can cause cells to shrink or swell as water moves in/out

Question 20

isotonic

Answer 20

solutions of nonpenetrating solutes having an osmolarity of 300 mOsm - cell neither shrinks nor expands
same concentration of nonpenetrating solutes as normal ECF

Question 21

hypotonic

Answer 21

solutions have a nonpenetrating solute concentration lower than that in cells - cell swells due to water moving into it by osmosis

Question 22

hypertonic

Answer 22

solutions with a nonpenetrating solute concentration greater than cells - cell shrinks as water moves out of it into lower water conc area

Question 23

tonicity

Answer 23

determined by concentration of nonpenetrating solutes in solution
not total osmolarity or penetrating solutes

Question 24

isoosmotic

Answer 24

solution containing 300 mOsmol/L of solute, regardless of its composition of penetrating and nonpenetrating solutes

Question 25

hyperosmotic

Answer 25

solution containing greater than 300 mOsmol/L of solute, regardless of its composition of penetrating and nonpenetrating solutes

Question 26

hypoosmotic

Answer 26

solution containing less than 300 mOsmol/L of solute, regardless of its composition of penetrating and nonpenetrating solutes