Cell Membrane, Membrane Transport, and Membrane Potential 3

Question 1

What passes through the membrane with simple diffusion?

Answer 1

hydrophobic/lipophilic substances

Question 2

What are characteristics of simple diffusion?

Answer 2

slow, unregulated, things passing directly through the membrane

Question 3

Does simple diffusion require a membrane?

Answer 3

no

Question 4

What is the rate of simple diffusion directly related to?

Answer 4

concentration gradient, temperature, and surface area

Question 5

What is the rate of simple diffusion inversely related to?

Answer 5

resistance and diffusion distance

Question 6

What passes through the membrane with facilitated diffusion?

Answer 6

hydrophilic/lipophobic substances

Question 7

What do hydrophilic/lipophobic materials require to pass through the membrane?

Answer 7

membrane channels or carriers

Question 8

What are some characteristics of facilitated diffusion?

Answer 8

faster, regulated, and require a plasma membrane

Question 9

What helps to regulate facilitated diffusion?

Answer 9

changing the resistance of the membrane

Question 10

Why does the rate of diffusion level off with facilitated diffusion?

Answer 10

requires carriers or channels that can become saturated

Question 11

What increases the rate of diffusion of hydrophobic substances?

Answer 11

increase in temperature, increase in surface area, increase in concentration gradient, decrease in resistance, and a decrease in diffusion distance

Question 12

What is osmosis?

Answer 12

the movement of water across a membrane down a gradient

Question 13

What allows for water to pass through the membrane?

Answer 13

aquaporins

Question 14

What three values change when water moves via osmosis?

Answer 14

1. solute concentration
2. water concentration
3. container volume

Question 15

Does osmotic equilibrium equal volume equilibrium?

Answer 15

no not necessarily

Question 16

What determines the direction that water will move to achieve equilibrium?

Answer 16

impermeable substances

Question 17

What is osmolarity?

Answer 17

the total free solute concentration of a solute (permeable and impermeable solutes)

Question 18

What is an isosmotic bathing solution?

Answer 18

when the bathing solution Osm is equal to the cytosolic Osm

Question 19

What is a hyposmotic bathing solution?

Answer 19

the bathing solution Osm is less than the cytosolic Osm

Question 20

What is a hyperosmotic bathing solution?

Answer 20

the bathing solution Osm is greater than the cytosolic Osm

Question 21

What is tonicity?

Answer 21

helps to determine the way that water will flow via osmosis
-only takes into account the impermeable substances

Question 22

What is an isotonic solution?

Answer 22

when the concentration of impermeable solutes = cell cytosol
-no net volume change

Question 23

What is a hypotonic solution?

Answer 23

when the concentration of impermeable solute is less than the cell cytosol
-cells in this solution will have a net influx of water and swell

Question 24

What is hypertonic solution?

Answer 24

when the concentration of impermeable solutes in the solution is greater than in the cell cytosol
-cells in this solution will lose water and will shrink

Question 25

What is the normal osmolarity of extracellular fluid?

Answer 25

300 Osm

Question 26

What is the osmolarity of normal cytosol?

Answer 26

300 Osm

Question 27

What are some systemically permeable solutes?

Answer 27

-ethanol
-fatty acids
-O2
-CO2
-steroids
-urea *
-glucose *
*not permeable in all cells, just when looked at systemically and in RBC

Question 28

What are some systemically impermeable solutes?

Answer 28

-Na
-K
-Cl
-HCO3
-protein