Action Potentials & Synaptic Transmission

Question 1

What are the 5 phases of the action potential?

Answer 1

1. Threshold
2. Rising Phase
3. Peak
4. Falling Phase
5. After Hyperpolarization

Question 2

What is the absolute refractory period? Relative?

Answer 2

Absolute:Inactivation period of Na+ channels
Relative: Requires more depolarizing current during AHP

Question 3

How is conduction speed related to axon diameter?

Answer 3

The larger, the faster

Question 4

Where are action potentials usually conducted and why?

Answer 4

Usually not conducted in soma and dendrites because they lack voltage-gated channels

Question 5

What are the advantages of myelination?

Answer 5

More rapid- saves times & Requires less active process - saves energy

Question 6

What is the Rate Law?

Answer 6

Firing (action potential) frequency reflects the magnitude of the depolarizing current or stimulus intensity

Question 7

What are the characteristics of electrical synapses?

Answer 7

Gap junctions; connexon formed by six connexin; bidirectional flow of ions; faster than chemical

Question 8

What was Otto Loewi’s experiment and what did he discover?

Answer 8

Frog heart experiment that demonstrated that neurons communicate by releasing chemicals. Used the vagus nerve in the heart

Question 9

What are the properties of Gray’s Type 1 Synapse?

Answer 9

asymmetrical, excitatory

Question 10

What are the properties of Gray’s Type 2 (II) Synapse?

Answer 10

Symmetrical, inhibitory

Question 11

What are dense-core synaptic vesicles?

Answer 11

Synthesized in the soma; packaged in vesicles in the Golgi and transported down the axon via microtubules