Neurotransmitters

What are synapses?

Where the axon terminals of neurons contact their target cells.

What is a chemical synapse?

A synapse where there is a gap between the axon terminals and target cell. Communication via chemicals.

What is an electrical synapse?

Synapses where the axon terminals physically touches the target cell. Contains gap junctions that allow the insides of the two cells to communicate.

What are the more common types of synapses?

Chemical synapses.

What covers most synapses in the CNS?

The end feet of astrocytes.

What is the gap is chemical synapses?

The synaptic cleft.

Where are synaptic vesicles located?

Within the pre-synaptic membrane of the neuron.

What are synaptic vesicles filled with?

Neurotransmitters.

Where are neurotransmitter receptors located?

On the surface of the post-synaptic membrane.

What kind of voltage-gated channels are on the pre-synaptic membrane?

Voltage-gated calcium channels.

What happens to the voltage-gated Ca channels when the AP reaches the terminal?

The membrane potential changes and opens the voltage-gated CA channels.

What results from the influx of Ca2+ into the pre-synaptic membrane?

The increased concentration causes changes to proteins on the synaptic vesicles and pre-synaptic membrane, resulting in fusion of the two.

What are the amounts are durations of NTs in the synaptic cleft dependent on?

The frequency and duration of the APs.

What are some categories of NTs?

Amino acids, peptides, monoamines, and others.

What are the defining traits of amino acids?

They possess an amino group (NH2) and a carboxylic acid.

What are peptides?

Polymers/chains of amino acids. Very large molecules.

What are monoamines/biogenic amines?

Organic molecules with an amino group connected to an aromatic group by a 2 carbon chain.

What are catecholamines?

A monoamine subgroup with a catechole group (benzene ring with 2 hydroxyl groups attached directly). Includes dopamine, epinephrine, and norepinephrine.

What are important amino acid NTs?

Glutamate, GABA, and glycine.

What is the most common excitatory NT in the nervous system?

Glutamate, as it usually induces depolarization.

What are the most common inhibitory NTs in the nervous system?

GABA (brain) and glycine (spinal cord), as they usually cause hyperpolarization of target cells.

What are some important monoamine NTs?

Serotonin, histamine, dopamine, epinephrine, and norepinephrine.

What functions are associated with monoamine NTs?

Attention, cognition, and emotion.

What is a type of peptide NTs?

Opioids such as endorphins.

What sensation are peptide NTs associated with?

Pain or the lack of it.

What is acetylcholine?

A non amino acid, monoamine, or peptide NT that is released by most autonomic neurons in the PNS and by motor neurons.

What is a method of NT clearance if the APs are firing at a slow frequency?

Diffusion of NTs out of the synapse.

What are some active methods of NT clearance from the synapse?

Enzyme removal, re-up take pumps, and astrocyte end feet (in the CNS).

What are re-up take pumps?

Structures on the pre-synaptic membrane that transport NTs released into the synaptic cleft back into the membrane to be recycled.

What is neuroplasticity?

How the nervous system changes in response to experiences. Changes in synapse that effect how information is transmitted through the nervous system.

What is potentiation?

When the strength of information flowing through a part of the nervous system increases.

What is depression?

When the strength of information flowing through the nervous system decreases.

When is neuroplasticity the highest?

During the development of the nervous system.

What leads to potentiation vs differentiation?

When parts of neurons/chains are used more often versus used less often.

Where can neuroplasticity happen?

At the synapse (synaptic neuroplasticity) and at the level of the entire cell (structural neuroplasticity).

What kinds of changes can lead to synaptic potentiation?

When more NTs are released from each AP, or a change in the receptors on the post-synaptic membrane that result in a bigger response to NTs.

What kinds of changes can lead to synaptic depression?

A decrease in the amount of NTs released from the pre-synaptic membrane and/or changes in the post-synaptic membrane making it less responsive to NTs.

What happens in potentiation with structural neuroplasticity?

When neurons are firing frequently, there is an increase in the number of synapses between them. Can be through increases/lengthening/branching of dendrites or branching of axon terminals.

What happens in depression with structural neuroplasticity?

When neurons fire less frequently, there is a loss of synapses through loss/shortening of dendritic branches and/or loss of axon terminals.

What is pruning?

The loss of parts or whole neurons through depression in structural neuroplasticity.

What kinds of potentiation/depression are synaptic neuroplasticity changes associated with?

Either short-term or long-term potentiation or depression.

What kinds of potentiation/depression are structural neuroplasticity changes associated with?

Primarily long-term potentiation or depression.