Topic 6 Nervous System: Neurotransmitters

Question 1

• Secreted at neuromuscular junctions and cause muscle contraction or relaxation
• In parasympathetic nervous system, and are released from pre and post ganglionic nerves
• Broken down by acetylcholinesterase, located on post-synaptic membranes found in nerve + muscle tissues, central + peripheral tissues, and sensory + motor fibers. Arc binds to Ach receptors on post-synaptic membranes for nerve transmission – acetylcholinesterase breaks down Ach to terminate the signal

Answer 1

1. Acetylcholine (Ach)

Question 2

• Glutamate: neurotransmitter at the neuromuscular junction in invertebrates, and is the most common CNS neurotransmitter in vertebrates
• Gamma aminobutyric acid: inhibitory neurotransmitter among brain neurons
• Glycine: inhibitory neurotransmitter among synapses of the CNS outside the brain

Answer 2

2. Amino Acids

Question 3

• Epinephrine, norepinephrine, dopamine, and serotonin (5HT): secreted between neurons of the CNS
  a. Epinephrine/norepinephrine act in the sympathetic nervous system and are released from post ganglionic nerves

Answer 3

3. Amino acid derived (biogenic amines)

Question 4

• Short chains of amino acids and are a diverse group including substance P and endorphins

Answer 4

4. Neuropeptides

Question 5

• Unlike most neurotransmitters, these are not stored in vesicles and are actually synthesized and released on demand
• Example: nitric oxide

Answer 5

5. Gases