2 - Ion Channels : Nervous 1
Terms
undefined, object
copy deck
- Ion channels
- What controls the movement of ions across the membrane of a neuron?
-
1. selective
2. passive or active
3. regionally located
4. functionally unique - What are four properties of ion channels?
- Integral proteins
- What are ion channels made of?
- They select certain molecules to let in, and select some to keep out.
- What does it mean to say "Ion channels are selective"?
-
1. charge of ion
2. size of ion
3. how much water theion attracts & holds around it. - What three factors determine the selectivity of an ion channel?
-
Active - have gates
Passive - are always open (leakage channels) & continuous ion movement - What's the difference between an active and passive ion channel?
- outside
- Is a resting neuronal cell membrane more positive inside or outside?
- membrane potential ??
- What is the result of the charge separation in a resting neuronal membrane?
- closed
- When the neuronal membrane is at rest are the voltage-gated channels opened or closed?
- It causes the voltage-gated channels to open or close.
- What happens to the voltage-gated channels when there is a nerve impulse (or action potential) in the neuronal membrane?
- Because a + ion is moving inward, making the inside of the membrane more +.
- Why, when the Na+ voltage-gated channel opens, does the membrane potential goes from -70 mV to less negative values.
- Because the + ion is moving outward, making the inside of the membrane more -.
- Why, when the K+ voltage-gated channel opens, does the membrane potential goes from +30 mV to more negative values (-70).
-
voltage - gated
chemically - gated - Give two general types of active channels.
- neurotransmitters (ACH & GABA)
- What will open a chemically-gated ion channel in a neuron?
- No
- When a neurotransmitter opens a chemically-gated channel, does the neurotransmitter go into the cell?
-
Na+ & K+
They move in both directions - When GABA binds to its receptor, which ion(s) will move across the membrane? In which direction will they move?
-
chloride ions
They move into the cell - When acetyl choline binds to its receptor, which ion(s) will move across the membrane? In which direction will they move?
- The neurotransmitter that binds to the receptor
- What determines the direction that ions move through an ion channel?
- in the cell membrane, dendrites, cell body, and axon
- On what parts of the neuron do we find passive channels?
- dendrites and cells
- On what parts of the neuron do we find chemically-gated channels?
-
Axon hillock
Unmyelinated axons nodes of Ranvier in myelinated axon. - On what parts of the neuron do we find voltage-gated channels?
- Voltage-gated channels
- are responsible for the generation of the action potential (nerve impulses)- the outgoing signal from the neuron
- Chemically-gated channels
- are responsible for potentials generated at synapses (synaptic potentials)
- Passive channels
- are responsible for the resting membrane potential