1-08 Chemical Events At The Synapse

Front 1

Objective

List the seven events that take place at a synapse.

Back 1

1. The neuron produces neurotransmitter. Smaller molecules are synthesized in the axon (or presynaptic) terminal, whereas larger ones such as peptides are synthesized in the cell body.

2. Larger neurotransmitters are transported from the cell body to the axon terminal.

3. The action potential makes its way down the axon to the presynaptic terminal, where it opens calcium channels that trigger the release of neurotransmitters into the synaptic cleft.

4. Once released, the neurotransmitters cross the cleft and attach to receptor sites on the postsynaptic neuron, exerting either an excitatory or inhibitory effect on this neuron.

5. After delivering their signal, the neurotransmitters detach from the receptors.

6. The neurotransmitter molecules may be broken down by enzymes or recycled by the presynaptic neuron.

7. Some postsynaptic neurons appear to release chemical substances that deliver a negative feedback signal to the presynaptic neuron, slowing down the release of additional neurotransmitters.

Front 2

Objective

Give an example of each of the six classes of neurotransmitters.

Back 2

1. Amino acids: GABA, glutamate
2. Modified amino acids: Acetylcholine
3. Monoamines:
a. Indolamines: Serotonin
b. Catecholamines: Dopamine, epinephrine, norepinephrine
4. Peptides: Endorphins, substance
5. Purines: ATP, adenosine
6. Gases: Nitric oxide (NO)

Front 3

Objective

Describe the process by which neurotransmitters are released.

Back 3

1. The action potential travels along the axon to the presynaptic terminal.

2. The depolarization of the membrane at the terminal opens up calcium gates.

3. Calcium entering the presynaptic terminal triggers the release of neurotransmitters.

Front 4

neurotransmitter

Back 4

A chemical messenger released by one neuron that can affect a second neuron

Front 5

amino acid

Back 5

The building block of protein molecules, containing an amine group (NH2) and a carboxylic acid (COOH)

Front 6

peptide

Back 6

A chain of amino acids

Front 7

acetylcholine

Back 7

A molecule similar to an amino acid, except that the hydrogens in the amine group have been replaced by methyl groups (CH3)

Front 8

monoamine

Back 8

A neurotransmitter containing a single amine group

Front 9

purine

Back 9

One of the building blocks of DNA that includes adenosine and its derivatives

Front 10

nitric oxide (NO)

Back 10

A gas released by many small local neurons

Front 11

catecholamine

Back 11

A class of monoamines that includes dopamine, epinephrine, and norepinephrine

Front 12

vesicle

Back 12

A tiny, spherical packet in which neurotransmitters are stored within the presynaptic terminal

Front 13

exocytosis

Back 13

The release of neurotransmitters in bursts from the presynaptic terminal into the synaptic cleft