Unit 1.Lec 4-Synthesis, Storage and Release of Neurotransmitters Flashcards
Explain Local Current Flow
Concepts to Remember
Action Potential propagationn along unmyelinated axon
Explain Saltatory Conduction
Concepts to Remember
AP propagation along myelinated axons. Much faster conduction
Explain AP Refractory Period
Concepts to Remember
- Time lag betweeen action potentials
- Absolute vs. Relative
Explain Multiple Sclerosis
Degeneration of the myelin sheath. Conduction is slower.
Explain Synaptic Transmission
Transmitting the action potential to another cell
List the types of synapses
- Electrical Synapse
- Chemical Synapse
Explain Electrical Synpase
Passive Communication via the direct electrical coupling of two cells through gap junctions
Explain Chemical Synpase
Communication through the release and binding of neurotransmitters
How are gap junctions made in electrical synapsis
- Several connexins make up one connexon
- Two connexons combine to make a gap junction
What are the advantages and disadvantages of gap junctions (electrical synapsis)?
- Pro: rapid signal transmission
- Con: Postsynaptic signal=presynaptic signal (identical signal, ie. less plasticity)
What are the pros and cons of neurotransmitters (chemical synapses)?
- Pros: Postsynaptic siganl differs from presynaptic signal
- Cons: Slow signal transduction
What are the 6 main types of neurotransmitters?
- Acetylcholine
- Amino Acids
- Purines
- Biogenic Amines
- Gases (NO, CO)
- Peptides (much larger)
Which neurotransmitters are classified as small molecules?
- Acetylcholine
- Amino Acids
- Biogenic Amines (dopamine, norepinephrine, epinephrine, serotin, histamine)
What are the two general categories of amino acid transmitters?
- Inhibitory
- Excitatory
What are the main inhibitory AA neurotransmitter? What are they responsible for and how does it occur?
- Inhibitory AA
1. 𝛾-aminobutyric acid (GABA)
2. Glycine - Primarily responsible for IPSP’s(Inhibitory Postsynaptic Potential) d/t an influx of Cl- ions and/or efflux of K+ ions
Drug e.g.- Phenobarbital, diazepan, vigabatrin
What are the main inhibitory AA neurotransmitter? What are they responsible for and how does it occur?
- Inhibitory AA’s
1. 𝛾-aminobutyric acid (GABA)
2. Glycine - Primarily responsible for IPSP’s(Inhibitory Postsynaptic Potential) d/t an influx of Cl- ions and/or efflux of K+ ions
(Drug e.g.- Phenobarbital, diazepan, vigabatrin)
What are the main excitatory AA neurotransmitter? What are they responsible for and how does it occur?
- Excitatory AA’s
1. Glutamate
2. Aspartate
3. Acetylcholine
4. Cathecholamines (Epi, NE, Dopamine)
5. Serotonin
6. Histamine - Primarly responsible for EPSP’s (Excitatory Postsynpatic Potential) d/t an influx of Ca2+
Drug e.g- Antagonist are Ketamine, Riluzole, and MSG is an Agonist)
List the biogenic amines neurotransmitters?
- Catecholamines
1. Dopamine
2. Epinephrine
3. Norepinephrine - Indoleamine
1. Serotonin - Imidazoleamine
1. Histamine
What are the precusors of dopamine, norepinephrine and epinephrine
- Tyrosine (which comes from diet or phenylalanine) is the prescusor to dopamine
- Dopamine is the precusor for norephoinephrine which can become epinephrine
What is the rate-limiting enzyme for tyrosine to become dopamine?
Tryosine hydroxylase ( which increased when stressed)
WHat is the precusor for histamine?
Histidine
Drug e,g.- H1 antagonist, diphnhydramine (lipophilic) + Loratadine/Claritin (lipophobic)
What is the prescursor for serotonin?
Tryptophan
What is the mechanism of action for peptide neurotransmitters?
- Peptide NT enter inactive (prodrug) and become active @ target site
List some examples (5) of pepitide neurotransmitters
- Brain-gut peptides
- Opoid peptides
- Pituitary peptides
- Hypothalamic-releasing peptides
- Miscellaneous peptides
How are peptide drugs administered?
Peptide drugs need to be injected b/c if digested the GI tract wiil cleave them rendering them inactive
What is the mechanism of processing peptide neurotransmitters?
Initially the prepetide is cleaved to turn into an active peptide
List the life cycle of neurotransmitters
- Synthesis
- Packing (Transport)
2a. Docking (Priming) - (Fusion) Release (Exocytosis)
3a. Budding (Endocytosis) - Binding
- Inactivation (Removal)
List the steps of Synthesis, & Packing/Transport of Small-Molecule Transmitter
- Enzymes synthesized in the cell body and transported to the presynaptic nerve terminal
- Transmitters (e.g. Ach, 5HT) are synthesized @ the presynaptic nerve terminal
- Transmitters are stored in endosomes which bud off small, CLEAR CORE vesicles
Where are small-molecule transmitters enzymes synthesized and transported?
- In the cell body
- Presynaptic nerve terminal
Where are the small molecule transmitters like ACh & 5HT synthesized?
Presynaptic nerve terminal
Where are the small molecule transmitters stored?
Endosomes which bud off small, CLEAR CORE vesicles
List the steps of synthesis, packing and transport of peptide transmitters
- Large pro-peptide transmitters + enzymes are synthesized in cell body
- Transmitter + enzymes are packaged in DENSE CORE vesicles which bud off Golgi apparatus
- Dense core vesicles are transported down axon via microtubles
- Emzymes process large pro-peptide at the presynaptic terminal
