Physiology Chapter 4: Cell Membrane Transport

Front 1

Transport Across Membranes
What membranes do? (2)
Why transport is important? (2)

Back 1

-What membranes do
=Separate material: ICF / ECF
=Allow exchange of material: ICF / ECF
-Why transport is important
=Obtaining O2 and nutrients
=Getting rid of waste products

Front 2

Membranes Are Selective (4)

Back 2

-Selectively permeable
=Permeable = to pass through
=Selective = restrictive
-Membranes allow the transport of some substances, but not others

Front 3

Extracellular Environment (5)

Back 3

-Includes all constituents of body outside cells
-7% of total body H20 is inside cells (intracellular fluid)
-33% is outside cells (extracellular fluid-ECF)
=20% of ECF is blood plasma
=80% of ECF is interstitial fluid contained in gel-like matrix

Front 4

Transport Across Plasma Membrane (2)

Back 4

-Plasma membrane is selectively permeable--allows only certain kinds of molecules to pass
-Many important molecules have transporters & channels

Front 5

Carrier-mediated transport ...

Back 5

involves specific protein transporters

Front 6

Non-carrier mediated transport ...

Back 6

occurs by diffusion

Front 7

Passive transport ...

Back 7

moves compounds down concentration gradient; requires no energy

Front 8

Active transport ...

Back 8

moves compounds up a concentration gradient; requires energy & transporters

Front 9

Driving Forces (4)

Back 9

-Include chemical and electrical forces
-Both forces = electrochemical force
=Passive
+Movement down the force
=Active
+Movement against the force

Front 10

Diffusion
Is random motion of molecules

Back 10

Net movement is from region of high to low concentration

Front 11

Non-polar compounds

Back 11

readily diffuse thru cell membrane

Front 12

Cell membrane is impermeable to

Back 12

charged & most polar compounds

Front 13

Charged molecules must have an ___ or ___ to move across membrane

Back 13

ion channel or transporter

Front 14

Rate of diffusion depends on: (4)

Back 14

-Magnitude of its concentration gradient
-Permeability of membrane
-Temperature
-Surface area of membrane

Front 15

Chemical Driving Force

Back 15

Magnitude of chemical driving force proportional to concentration gradient

Front 16

A substance will diffuse down its own
___

Back 16

concentration gradient

Front 17

Electrical Driving Force
Direction of force depends on

Back 17

Polarity charge on particle

Front 18

Osmosis
Is net diffusion of H20 across a selectively permeable membrane (3)

Back 18

-H20 diffuses down its own concentration gradient
-H20 is less concentrated where there are more solutes
-H20 diffuses down its concentration gradient until its concentration is equal on both sides of membrane

Front 19

Isotonic

Back 19

have same osmotic pressure – concentration

Front 20

Hypertonic

Back 20

-have higher osmotic pressure – conc.
=Will have higher solute conc. than cell
=Cell will lose water

Front 21

Hypotonic (2)

Back 21

-have lower osmotic pressure
=Will have lower solute conc. than cell
=Cell will gain water
=Cell 65% solute (35% water)
=Outside 55% solute (45% water)

Front 22

Osmolality vs. Tonicity (2)

Back 22

-Tonicity implies a membrane that is impermeable to the solutes on either side of it.
-Osmolality is a measure of the osmotically active particles in a solution. It makes no explicit assertion with respect to the solute permeability of any involved membranes

Front 23

Isosmotic

Back 23

solutions have same osmolality as plasma

Front 24

Hypo-osmotic

Back 24

solutions have lower osmotic pressure than plasma

Front 25

hyperosmotics

Back 25

have higher pressure than plasma

Front 26

Osmolality

Back 26

is 1mole in 1kg H2O
=Mole is number of molecules and thus gives us the ratio to water (thus concentration)

Front 27

Regulation of Blood Osmolality (4)

Back 27

-Blood osmolality maintained in narrow range around 300m Osm
-If dehydrated, osmoreceptors in hypothalamus stimulate:
=ADH release
+Which causes kidney to conserve H20
=& thirst

Front 28

Two aqueous solutions are separated by a semipermeable membrane. Solution A is 10% starch, and solution B is 5% starch. What will occur?

Back 28

Water will move from solution B to solution A.

Front 29

Two aqueous solutions are separated by a semipermeable membrane. Solution A is 10% water, and solution B is 5% water. What will occur?

Back 29

Water will move from solution A to solution B.

Front 30

A cell is placed into a hypertonic solution. What will occur?

Back 30

Water will move out of the cell.

Front 31

A cell has an osmolality of 300 and is placed into a solution with a osmolality of 600. What will be the net movement of water?

Back 31

Water will move out of the cell.

Front 32

Molecules too large & polar to diffuse are transported across membrane by ___

Back 32

protein carriers

Front 33

Active Transport
Example: Sodium–Potassium Pump

Back 33

-Uses ATP to move 3 Na+ out & 2 K+ in
=Against their gradients

Front 34

Active Transport
Sodium linked glucose pump (3)

Back 34

-Secondary active transport of glucose
-Diffusion of Na+ provides energy
-Pump actively transports glucose

Front 35

Transport Across Epithelium (2)

Back 35

-Transport across cell
-Involves two membranes

Front 36

Epithelium: Glucose Transport (3)

Back 36

-Secondary active transport: apical
-Facilitated diffusion: basolateral
-Glucose transported across cell

Front 37

Cystic Fibrosis (2)

Back 37

-Thick respiratory mucus
-Defect in transport mechanism