BIO 220 Human Anatomy & Physiology
Neurotransmitters and Neuromodulators (Text Reference pages 428-430)
I.
Neurotransmitters and neuromodulators: This information is important for understanding
how chemical transmission occurs in general and how it is regulated across the synapses
of the PNS as well as in the CNS (spinal cord and brain). Their function, their
enhancement, inhibition, or mimicry has important pharmacological implications.
II.
Some general information:
A. Neurotransmitters work in various ways. They may be ligands that bind to ligand
receptors that open or close ion channels. Some are slower than others because they
must stimulate a second messenger to carry out the actual function of the
neurotransmitter.
B. Neurotransmitters may be excitatory (create EPSP’s) in some locations or may be
inhibitory (create IPSP’s) in other locations. Their action depends on the receptor
cells and their locations.
C. Some neurotransmitters are hormones. Within the brain there are neurosecretory cells
that secrete hormones. Give examples that you know about the hypothalamus.
D. In some cases, there are neuromodulators that modify the activities at the synapse.
II.
Describe each of the following neurotransmitters or neuromodulators.
A. Give the following information for each of the neurotransmitters or neuromodulators
listed below.
1. Indicate if it is basically associated with the PNS or CNS.
2. Where does it function/how does it function/what effects does it have on the
body?
3. Is it excitatory or inhibitory (it may vary with location). This means—will it
create and EPSP or an IPSP?
4. By which mechanism does it work (Na+, Cl-, K+ gates/channels, etc.).
5. Where appropriate, give the enzyme that breaks down the neurotransmitter or
explain how it is removed.
6. Give clinical example/applications when possible.
B. Neurotransmitters and neuromodulators
1. Small-molecular neurotransmitters
a. Acetylcholine (Ach)
1) Cholinergic
2) Neuromuscular junction (nicotinic receptors)
a) Nicotine
b) Caffeine
3) Heart (muscarinic receptors)
Revised Fall 2005
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BIO 220 Human Anatomy & Physiology
Neurotransmitters and Neuromodulators (Text Reference pages 428-430)
4) Deactivated by ________________.
a) Malathion and nerve gas
b) Clostridium botulinum toxin
c) Curare
5) Examples diseases/disorders
a) Alzheimer’s
b) Myasthenia gravis
b. Amino acids
1) GABA (gamma amino butyric acid)
a) 1/3 of all brain synapses
b) Inhibitory
c) (EPSP or IPSP?)
d) Antianxiety drugs as agonists (benzodiazepine class, ie: Valium)
2) Glycine
a) Inhibitory in spinal cord (how does it work?)
b) EPSP or IPSP?
c) Strychnine connection?
3) Glutamate
a) The “stroke neurotransmitter” (read CVA and TIA page 492)
b) ½ of all synapses in the brain communicate via glutamate
c) Excitatory in CNS (brain and spinal cord)
d) EPSP or IPSP?
e) Excitotoxicity (describe in detail)
4) Aspartate (similar to glutamate)
Revised Fall 2005
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BIO 220 Human Anatomy & Physiology
Neurotransmitters and Neuromodulators (Text Reference pages 428-430)
c. ATP and other purines
1) Excitatory in CNS and PNS (usually in combo w/ another neurotransmitter)
2) Adenosine
3) Phosphates (triphosphate, diphosphate, monophosphate)
4) ATP and Ach or NE
d. Biogenic amines
1) Excitatory or Inhibitory depending on receptor (there are at least 3 kinds of
receptors for each biogenic amine)
2) Catecholamines
a) Synthesized from amino acid ________________________.
b) Reuptake into __________________________.
c) Or Destroyed by enzymes _________________________ (
and ________________________________ (
)
).
d) Adrenergic fibers produce _______________ and attach to adrenergic
receptors (alpha and beta receptors)
e) Norepinephrine (NE)
f) Epinephrine
g) Dopamine—the “feel good” neurotransmitter. Explain.
3) Serotonin (5-hydroxytryptamine)
a) Serotonin reuptake inhibitors
b) How does this act as antidepressant?
4) Melatonin-Pineal Gland (see Chpt. 18, page 618)
a) Day-night cycle
b) Darkness
c) Relationship to NE?
d) Seasonal Affective Disorder (SAD)
e) Jet Lag
Revised Fall 2005
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BIO 220 Human Anatomy & Physiology
Neurotransmitters and Neuromodulators (Text Reference pages 428-430)
e. Gases
1) Nitric Oxide (NO) Note, this is NOT nitrous oxide (laughing gas).
a) How is this neurotransmitter different from the others?
b) Nitric oxide ____________(NOS) from amino acid _______________.
c) Not the same as nitrous oxide—explain.
2) Carbon monoxide (CO)
2. Neuropeptides
a. Enkephalins, endorphins, and dynorphins (natural opiates)
1)
How do they work?
2)
What is their relationship to substance P?
b. Substance P (how does this compare to a above)
c. Morphine (careful—it’s NOT made by the body)
III.
Enzymes that deactivate neurotransmitters
A. Answer the following questions about each of the neurotransmitters listed below (B).
1. With which neurotransmitter do you associate each?
2.
Which neurotransmitter does each deactivate or break down?
3. Can these create EPSP’s or IPSP’s? Explain! Be careful—this is a trick question.
B. Enzymes (Hint: Notice these are enzymes!)
1. Cholinesterase (AChE)
2. COMT (Cathechol-O-methyltransferase)
3. MAO (Monoamine oxidase)
4. Nitric oxide synthase (NOS)
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