Chapter 5: Tonicity and Membrane Transport

Question 1

Aquaporins

Answer 1

allows water to go through plasma membranes. AQ1

Question 2

Tonicity

Answer 2

forces water to move across a cell (hyper/hypotonic forces)

Question 3

Selective Permeability

Answer 3

Allow some but NOT other molecules to go through, based on: size, charge, polarity, hydrophilic/phobic factors

Question 4

Passive Movement

Answer 4

requires no energy for the cell to spend ATP (simple/facilitated diffusion and filtration)

Question 5

Active Movement

Answer 5

requires cell to spend cellular energy (ATP),

Active Transport

Question 6

Osmosis

Answer 6

Movement of particles from an area of HIGH concentration to an area of LOW concentration. It happens through the tonicity (solute) pressure
Forces water to go through the plasma membrane of the cell,

Question 7

Concentration Gradient

Answer 7

difference between area of [high] and area of [low]

100 —> 10 = fast rate of concentration

Question 8

Filtration

Answer 8

1. ) hydrostatic (water) pressure
2. ) Forces water to go through a filter,
3. ) Kidney filtration (renal tissue is the filter) is important in removing waste from the blood,
4. ) Filtration of fluid at capillaries is governed by Starling Law of capillary diffusion.

Question 9

Facilitated Diffusion

Answer 9

1.) Carrier or pore - mediated transport,
DOES NOT require ATP or cellular energy.
2.) Osmosis of water is a type of facilitated diffusion
3.) Large concentration gradient= faster rate
Small concentration gradient= slower rate

Question 10

Factors that Affect Diffusion Rate

Answer 10

1. ) Temperature: Higher temperature, faster rate.
2. ) Molecular weight: Higher molecular weight, slower rate.
3. ) ‘Steepness of concentration gradient: Larger difference between concentrations, faster rate.
4. ) Membrane surface area: Larger surface area, faster rate.
5. ) Membrane permeability: Increased permeability, faster rate.

Question 11

Isotonic Solution

Answer 11

1. ) equal concentration on non-permeating molecules.

2. ) Cells in 0.9% saline solution (NaCl) retain their volume.

Question 12

Hypertonic Solution

Answer 12

1. ) due to high concentration of non-permeating solutes.
2. ) Cells in 2% NaCl will loose water, shrink, cellular membrane may rupture and cell dies (water moves toward hypertonic solution).

Question 13

Hypotonic Solution

Answer 13

1. ) due to lower concentration of non-permeating solutes.

2. ) Cells in distilled water will gain water, swell and burst (because water moves toward hypertonic solution).

Question 14

Blood Osmolarity Range

Answer 14

280 - 295 mOsm/L

Question 15

Active Transport Process

Answer 15

1.) Molecules move against their concentration gradient from LOW to HIGH
2.) Process: Carrier mediated transport spends ATP,
Carrier binds to ligand,
Carrier is phosphorylated by ATP,
Carrier changes conformation (shape),
Carrier releases ligand to other side of membrane.

Question 16

Sodium-potassium ATPase Pump

Answer 16

1.) Pumps 3 Na+ ions out of the cell and 2 K+ ions into cell
2.) High Na+ in Extracellular fluid or ECF (low in ICF)
High K+ in Intracellular fluid or ICF (low in ECF)
3.) Is Electrogenic meaning it produces a charge (more negative inside cell)

Question 17

Symport

Answer 17

Molecules move in the same direction,

Ex, sodium-glucose transport proteins (SGLTs)

Question 18

Antiport

Answer 18

One molecule moves in one direction, the other molecule in the opposite direction,
Ex. Na+/K+ pump (3 Na+ out, and 2 K+ in).

Question 19

GLUT

Answer 19

Glucose transporter/uniport

Question 20

SGLUT

Answer 20

Na+ and glucose moves with the concentration gradient

Question 21

Endocytosis

Answer 21

Into the cell

Ex: Phagocytosis and Pinocytosis (water

Question 22

Exocytosis

Answer 22

Out of the cell

Ex: Insulin from pancreas