Chapter 13: Neurotransmission

Types of transmission

Chemical and electrical

Electrical transmission

1. Physical connection between cells

2. Continuous flow of cytoplasm between cells

3. Passive flow of ions and small molecules

4. Allow for fastest transmission

Chemical transmission

1. Cells separated via synapse

2. Secreted/released factors produce effects on post-synaptic cell

3. Most varied and abundant synapses

Gap junctions physically…

Tether cells together

Do gap junctions cluster together?

Yes

Gap junctions are made up of how many hemichannels?

2

What are connexons?

A hemichannel

What is a connexon made up of?

6 connexins

Each connexin is encoded by

20+ genes

Gap junctions are generally open or closed?

Open

What do gap junctions allow for free passage of?

1. Ions

2. Signaling molecules

3. Small molecules/metabolites

Channel structure will determine sensitivity to what?

Regulators

In astrocyte gap junctions, what is taken up?

Extracellular potassium

Locations of gap junctions

yes

Acetylcholine is the only small neurotransmitter not what?

Synthesized from an amino acids?

Bar one, what are all small neurotransmitters synthesized from?

Amino acids

Bar one, where are all small neurotransmitters synthesized?

The cytoplasm

Biogenic amines

Dopamine

Noradrenaline

Adrenaline

What is TH?

Tyrosine hydroxylase

What is L-AADC?

Aromatic amino acid decarboxylase

DBH?

Dopamine-beta-hydroxylase

PNMT

Phenylethanolamine-n-methyltransferase

What is the only small neurotransmitter not synthesized in the cytoplasm?

Norepinephrine (noradrenaline)

What are tyrosine hydroxylase and l-aadc used for?

Enzymes to be used as markers to show dopamine production.