Action potentials

Question 1

what do glia do?

Answer 1

provide physical support, control nutrient flow and are involved in phagocytosis

Question 2

Astrocytes

Answer 2

Provide physical support and transport nutrients to neurons

increase or decrease communication between neurons

Question 3

Oligodendroglia

Answer 3

Provide physical support and form the myelin sheath CNS axons (myelinating)

Question 4

Schwann Cells

Answer 4

form myelin for PNS axons (myelinating)

Question 5

Microglia

Answer 5

Involved in phagocytosis and brain immune function (myelinating)

Question 6

sheath layers around peripheral nerves

Answer 6

1. endoneurium: separates individual axons
2. perineurium: surrounding fascicles (bundles of axons)
3. epineurium: encloses entire nerve trunk

Question 7

what are stem cells used for?

Answer 7

Precursor to Neurons & Glial Cells
Self-renew
Regenerative medicine

Question 8

what are leak channels?

Answer 8

a small number of ions diffuse across the cell membrane

Question 9

what are Modality Channels ?

Answer 9

sensory neuron reacting to detecting mechanical force, temperature or chemical changes

Question 10

what are Ligand-gated Channels?

Answer 10

channel opens when neurotransmitter binds to receptor site. Generates local potential.

Question 11

what are Voltage-gated Channels?

Answer 11

structural change of the channel due to the electrical potential. Opens and closes quickly

Question 12

what is an Electrical Potential?

Answer 12

the difference in electrical charge across the membrane

Question 13

what are Three types of electrical potential?

Answer 13

Resting membrane potential
Local Potential
Action Potential

Question 14

what is the Resting membrane potential (RMP)?

Answer 14

the difference in voltage between the inside and outside of the axon membrane when the neuron is not transmitting any information

aka No net change in ions across the membrane

Question 15

what is a Local potential?

Answer 15

change in voltage that spreads only a short distance

Question 16

how do action potentials occur?

Answer 16

A large depolarizing signal along the axon
Starts at the axon hillock
All or None
Sudden influx of NA+ through voltage-gated channels.
Depolarization must reach threshold
(-55 mV)

Question 17

Electrochemical Transmission

Answer 17

1. Dendrites receive chemical message from adjoining cells
2. Chemical messengers activate receptors on dendritic membrane
3. Receptor activation opens ion channels, which can alter membrane potential
4. Action potential can result which is propagated down membrane
5. Action Potential arrives at presynaptic terminal
6. Presynaptic terminal depolarizes opening voltage-gated CA++ channels
7. CA++ triggers movement of Neurotransmitter vesicles
8. Synaptic vessicles fuse with presynaptic terminal
9. Vesicle opens in an omega
10. Action potential causes release of transmitter from axon terminals

Question 18

what is neurotransmitter release triggered by?

Answer 18

1. # of Action Potentials
2. Duration of stimulus to presynaptic cell
3. Increase in level of the strength of the stimulus

Question 19

how does the postsynaptic potential occur?

Answer 19

After the neurotransmitter binds to postsynaptic receptor ion channels open which result in:

1. Excitatory Postsynaptic Potential
2. Inhibitory Postsynaptic Potential

Question 20

what occurs during the excitatory postsynaptic potential?

Answer 20

Depolarization
Na+ or CA++
i.e. Acetylcholine at the neuromuscular junction

Question 21

what occurs during the Inhibitory Postsynaptic Potential?

Answer 21

Cl- flow into neuron or K+ flow out of neuron
Hyperpolarization
i.e GABA