General Neurobiology

Question 1

___ myelinate in the CNS, ___ myelinate in the PNS

Answer 1

Oligodendrocytes myelinate in the CNS, Schwann cells myelinate in the PNS

Question 2

Much neutrotransmitter synthesis occurs. . .

Answer 2

. . . in the dendritic processes by local protein synthesis.

ER and Golgi-like organelles are present in these distal processes, enabling this protein synthesis and transport in the presence of mRNA.

Question 3

Rapid transport of materials along the axon is the result of ___

Answer 3

Rapid transport of materials along the axon is the result of microtubule transport (NOT filamentous actin)

Question 4

Nernst equation (for chemical potential across a cell membrane)

Answer 4

Question 5

Goldman-Hodgkins-Katz equation

Answer 5

Nernst equation corrected for multiple ions and ionic permeability

Question 6

Hodgkin-Huxley model of neuron depolarization

Answer 6

1. Action potentials are all-or-nothing
2. Action potentials are regenerative (they do not diminish in amplitude as they propagate)
3. Delayed reactivation of K channels and inactivation of Na channels results in a refractory period.

Question 7

What is the approximate maximum frequency of nerve firing in a human?

Answer 7

1,000 Hz (about 1 / millisecond)

Question 8

Factors that determine speed of action potential propagation

Answer 8

1. Axon diameter (larger axon, increased length constant, faster transmission)
2. Myelination (increased membrane resistance, increased length constant, faster transmission)

Question 9

Why do we have nodes of Ranvier?

Answer 9

Because even highly myelinated membranes have some amount of current leakage. Having nodes of Ranvier with highly concentrated ion channels allows for “renewal” of the action potential amplitude at several steps along the axon. This is also referred to as “saltatory conduction.”

Question 10

Tetrodotoxin

Answer 10

Puffer-fish derived Na+ channel blocker

Widely used to experimentally block voltage-gated Na+ channel firing.

Question 11

Tetraethylammonium

Answer 11

Selective K+ channel blocker

Question 12

Equation for current carried by an ion channel

Answer 12

Question 13

Highly organized pre-synaptic terminal

Answer 13

Question 14

Facilitating vs depressing synapses

Answer 14

Describes how a synapse responds to repeated stimulation.

A facilitating synapse results in successively amplified post-synaptic responses, while a depressing synapse results in successively diminished post-synaptic responses.

Question 15

Highly organized post-synaptic density (example from a glutaminergic neuron)

Answer 15

Question 16

PSD-95

Answer 16

Post-sypantic density-95
Common structural protein in post-synaptic densities that contains multiple domains for protein-protein interaction, including three PZD domains, which bind to C-terminal peptides with a specific motif occurring in many transmembrane receptors.