Unit 1.Lec 6-Neurochemical Circuitry

Question 1

What is synaptic transmission and what are the two ways it occurs?

Answer 1

• Process by which a neuron communicates with a target cell across a synapses
  1. Chemical transmission
  2. Direct contact

Question 2

Explain Chemical Transmission

Synaptic Transmission

Answer 2

Involves neurotransmitters

Question 3

Explain Direct Contact

Synaptic Transmission

Answer 3

Can be electrical or involve protein-protein interactions

Question 4

Characteristics of Chemical Synapses

Answer 4

• Synaptic cleft much larger than electrical synapses
• Involves calcium-dependent neurotransmitter release

Question 5

What is a neurotransmitter?

Answer 5

An endogenous substance that is released from a neuron and acts on the recpetor site to produce a functional change in the properties of the cell on which the receptor is located

Question 6

List the classes of neurotransmitters

Answer 6

• Classical (small molecules)
• Nonclassical (peptides 3-30 amino acids long)
• Unconvential

Question 7

List the Classical (small molecule) NTs

Answer 7

• Acetylcholine (ACh)

Biogenic amines

• Dopamine (DA)
• Epinephrine (Epi)
• Norepinephrine (NE)
• Serotonin (5-HT)
• Histamine (Hist)

Amino Acids

• ϒ-amino butyric acid (GABA)
• Glycine (Gly)
• Glutamate (Glu)
• Aspartate (Asp)

Question 8

List the Nonclassical NTs

Answer 8

• Somatostatin (SS)
• Cholecystokinin (CCK)
• Vasoactive intestinal peptide (VIP)
• Substance P (SP)
• Enkephalin (Enk)
• Endorphin (End)
• Dynorphin (Dyn)
• Neuropeptide Y (NPY)
• Neurotensin (NT)
• Thyrotropin-releasing hormone (TRH)
• Orexin (hypocretin)

Question 9

List the Unconvential NTs

Answer 9

• Gases (CO, NO)
• Growth factors (BDNF, NGF)

Question 10

Life Cycle of Convential Neurotransmitters

Answer 10

1. Transmitter is synthesized and then stored in vesicles
2. An action potential invades the presynaptic terminal
3. Depolarization of presynaptic terminal causing opening of voltage-gated Ca2+ channels
4. Inlfux of Ca2+ through channels
5. Ca2+ causes vesicles to fuse with presynaptic membrane
6. Transmitter is released into synaptic cleft via exocytosis
7. Transmittter binds to receptor molecules in postsynaptic membrane
8. Opening or closing of postsynaptic channels
9. Postsynaptic current causes excitatory or inhibitory postsynaptic potential that changes excitabilty of the postsynaptic cell
10. Retrieval of vescular membrane from plasma membrane

Question 11

How is Nitric Oxide (NO) synthesized?

Unconvential Neurotransmitter

Answer 11

Synthesized for Arginine via Nitric Oxide Synthase on demand

Question 12

Unconvential NT: Nitric Oxide

• Storage?
• Release?
• Receptors?

Answer 12

• NOT stored in vesicles
• Released via diffusion (not exocytosis)
• NO receptors