Action Potential and Ion Channels

The Nervous System: Ion Channels
1. What structures in the cell membrane function as ion channels? Intergral Proteins

2. Ion channels are selective for specific ions. What three characteristics of the ions are important for this selectivity?

a. Charge on ion (+ or -)

b.Size
c. The amount of water the Ion attracts

3. Channels can be classified as either gated or nongated channels. A sodium channel that is always open would be classified as a/an non-gated channel.

4. Would sodium ions move into or out of the neuron through these channels?

Into

5. Voltage-gated potassium channels open at what voltage? -130 mV

6. Acetylcholine (ACh) and GABA are neurotransmitters that open chemically-gated channels. What ions pass into the cell when these channels are activated?

a. ACh: Sodium (Na+) ions

b. GABA: Chlorine (Cl-) ions

7. Ion channels are regionally located and functionally unique. List all the areas on the neuron and the type of potential dependent on the following types of ion channels:

|Channels |Areas on the neuron |Type of potential |
|Nongated |dendrites, cell body, axon |resting membrane |
|Chemically-gated |dendrites, cell body |synaptic |
|Voltage-gated |axon hillock, unmyelinated axons, nodes of|action |
| |Ranvier (myelinated axons) | |

8. From the quiz, place an “X” by the characteristics of voltage-gated sodium channels.

______ Always open

___x___ Found along the axon
__x____ Important for action potential
___x___ Opened and closed by gates
______ Found on the