Week 5- Ion channels/ PBL- Fitz

Question 1

Compare and contrast ion channels and transporters

Answer 1

ION CHANNELS:
holes in membrane
transports small things
flow is always passive
does NOT require energy
goes DOWN electrochemical gradient
Transports at high rates

TRANSPORTERS:
Never opens to both sides of the membrane at the same time
Can trasport ion but ALSO large molecules
Can be passive but can also be ACTIVE, goes AGAINST gradients
transports at slower rates
establishes gradients

Question 2

What are the critical features of ion channels?

Answer 2

Selectivity- differ in number and type of ions that will pass
Gating- structure opens and closes channels
Inactivation- only some channels have, can prevent flow of ions through channel
Bidrectional Flow

Question 3

Rank extracellular concentrations of ions

Answer 3

Na > Cl > K > Ca

Question 4

How do you determine reversal potential?

Answer 4

Reversal Potential= 61/z log (concentation outside/ concentration inside)

z= electrical charge of ion

Question 5

Define depolarization and hyperpolarization

Answer 5

depolarization makes membrane potential more POSITIVE

hyperpolarization makes the membrane potential more NEGATIVE

Question 6

What is ohms law?

Answer 6

V=IR

voltage = current (voltage) x resistance

Question 7

What are the different types of gating?

Answer 7

leaky
mechanical
ligan
voltage gated
spontaneous

Question 8

Normal flow of primary electrolytes based on concentrations

Answer 8

Na flows into cell
K flow out of the cell
Ca+2 flows into cell
Cl- flows into cell

Question 9

Reversal Potential for Na

Answer 9

+60

Question 10

Reversal Potential for K+

Answer 10

-88

Question 11

Reversal Potential for Ca+

Answer 11

+214

Question 12

Reversal Potential for Cl-

Answer 12

-61