Ch 4. Ion channels & signaling

Question 1

neuronal signals are controlled by

Answer 1

the flow of ions passing through ion channels

Question 2

ion channels

Answer 2

are selective for either cations or anions
- cation channels can get even more selective
ex: allowing sodium ions only to pass through
ion current can be measured through channel
fluctuate between closed and open states

Question 3

what happens when ion channels open?

Answer 3

they pass current allowing the ions to either flow into the cell or out of the cell

Question 4

what are two factors that determine ion channel conductance?

Answer 4

permeability and concentration

Question 5

what is ion channel movement driven by?

Answer 5

concentration gradient
and electrical potential gradient

Question 6

What changes the membrane potential?

Answer 6

movement across the nerve cell membrane
ex: inner movement of Na+ inside the cell depolarizes it by reducing the net charge on the inner surface of the membrane
ex: outer movement of K+ outside of the cell results in hyperpolarization by increasing the net charge on inner surface of membrane
ex: inner movement of Cl- causes hyperpolarization

Question 7

phospholipid bilayer

Answer 7

makes up the cell membrane
consists of polar hydrophilic heads facing the outside layer (on both sides) and hydrophobic tails that face inwards

Question 8

what is the purpose of the hydrophilic and hydrophobic layers of the cell membrane?

Answer 8

It allows the cell membrane to lower its permeability meaning it allows the membrane to be choosy with what it allows in and out of the cell.
lipids are somewhat selective to water and impermeable to ions

Question 9

what is the relation of permeability in terms of high and low

Answer 9

high permeability allows ions/particles to pass through easily
low permeability doesn’t allow ions/particles to pass though easily
“permeability” how much is the membrane permitting to pass through? is it permitting a lot? or a little?

Question 10

how do ions pass through the cell membrane?

Answer 10

specified ion channels that allow ions to pass through (with control given certain properties such as the gate) are imbedded into the membrane bilayer

Question 11

what ion channels are imbedded into the neuronal membrane?

Answer 11

Potassium, Sodium, Chlorine, and Calcium

Question 12

what controls the opening and closing of the gates in ion channels?

Answer 12

membrane potential