Synaptic Transmission and AP

Question 1

2 types of synapses between neurons

Answer 1

Chemical - most common

Electrical

Question 2

How do chemical synapses work?

Answer 2

Unidirectional. Presynaptic membrane secretes neurotransmitters that act on receptors in the postsynaptic neuron. Can be excitatory or inhibitory.

Question 3

Conventional neurotransmitters in chemical synapses

Answer 3

Amino acids
Biogenic amines - dopamine, serotonin, Epi/NorEpi
Achetylcholine
Endorphins

Question 4

Unconventional neurotransmitters in chemical synapses

Answer 4

Endocannabinoids

Gastrotransmitters

Question 5

How do electrical synapses work?

Answer 5

Cytoplasm of adjacent cells is directly connected via Gap Junctions. Allows for bidirectional free movement of ions.

Question 6

2 types of chemical synapse receptors

Answer 6

Metabotropic

Ionotropic

Question 7

What type chemical synapse receptor acts through a second messenger system?

Answer 7

metabotropic.

Question 8

Give an example of a metabotropic receptor

Answer 8

GPCRs open ion channels and then activate cAMP (a second messenger)

Question 9

What type of chemical synapse receptor directly opens ion gated channels?

Answer 9

Ionotropic

Question 10

What ion channel is opened by excitatory neurotransmitters and induces depolarization?

Answer 10

Cation (Na+ channels)

Question 11

What ion channel is opened by inhibitory neurotransmitters and induces hyperpolarization?

Answer 11

Anion (Cl- channels)

Question 12

What are graded potentials?

Answer 12

local membrane potentials that integrate at the axon hillock to generate an action potential

Question 13

What determines the strength of a graded potential?

Answer 13

intensity of the stimulus

Question 14

What is the threshold voltage that the integration of graded potentials must reach to generate an AP at the trigger zone?

Answer 14

-55mV

Question 15

Depolarizing graded potentials

Answer 15

Shift toward threshold (+)
Excitatory neurotransmitters (cation channels)
Excitatory post synaptic potentials (EPSP)

Question 16

Hyperpolarizing graded potentials

Answer 16

Shift away from threshold (more neg)
Inhibitory neurotransmitters (anion channels)
Inhibitory post synaptic potentials (IPSP)

Question 17

2 types of graded potentials

Answer 17

Spatial

Temporal

Question 18

How do spatial graded potentials generate an AP?

Answer 18

Graded potentials from different synapses collect in the axon hillock. If the sum of the EPSP and IPSP reaches -55mV, an AP occurs.

Question 19

How do temporal graded potentials generate an AP?

Answer 19

Successive discharges from a single synapse collect in the post synaptic neuron. If the discharges are rapid enough to combine, and reach -55mV, an AP occurs.

Question 20

What is saltatory conduction?

Answer 20

Action potentials occur only at Nodes of Ranvier in myelinated fibers. AP jumps from node to node.

Question 21

What do Nodes of Ranvier have a lot of that make them so good at conducting electrical impulses?

Answer 21

Ion channels

Question 22

Decremental conduction

Answer 22

Decrease in stimulus which leads to decrease in response down the fiber.

Corrected in each Node of Ranvier