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17 Cards in this Set
- Front
- Back
Types of Synaptic Connections Between Neurons
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1. Axodendritic
2. Axosomatic 3. Axoaxonic |
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Axoaxonic
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Axoaxonic is widely used: Neuron A targeting the nerve terminal of neuron B to influence release
Effect can be either inhibitory or stimulatory Inhibitory: Often seen with opiates, cannabinoids, and GABA at GABAB receptors Excitatory: Often seen with acetylcholine at nicotinic receptors |
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Clicker Question #1
Which type of synaptic connection would not influence the firing rate of the target neuron? |
A. Axosomatic
B. Axodendritic C. Axoaxonic D. All of the above |
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Classical Neurotransmitters
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1. Amino Acids
a. Glutamate b. GABA c. Glycine 2. Monoamines a. Dopamine b. Norepinephrine c. Serotonin 3. Acetylcholine |
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Non-classical Neurotransmitters
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1. Neuropeptides
a. Endorphins and enkephalins b. Corticotropin-releasing factor 2. Lipids a. Anandamide 3. Gases a. Nitric Oxide |
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Clicker Question #2
Which type of transmitter category offers the possibility of having the greatest number of members? |
A. Amino Acids
B. Biogenic Amines (Monoamines) C. Gases D. Neuropeptides |
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Co-Localization
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Having more than one neurotransmitter (NT) in the same nerve terminal
Could be two “classical” NTs or a classical NT + a peptide The peptide could be a NT or a “neuromodulator” Neuromodulator: Isn’t a signal by itself, but modulates the effect of the NT |
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Neuromodulation
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Example: Calcitonin gene-related peptide (CGRP)
Released from motor terminals at the neuromuscular junction in response to high frequency stimulation cAMP which protein kinase A activity which phosphorylation of the nicotinic receptor This produces a desensitization, so this is a form of modulatory regulation to tone down the effect of high levels of stimulation |
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Clicker Question #3
True or False. One difference between neuropeptide transmitters and biogenic amine transmitters is that the release of biogenic amine transmitters is calcium-dependent. |
A. True
B. False |
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Types of Receptors
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Ionotropic (Ligand-Gated, Transmitter-Gated). Examples: Nicotinic, GABAA
Metabotropic (G Protein-coupled). Examples: Muscarinic, Catecholamine Tyrosine Kinase. Examples: Insulin, Nerve Growth Factor (NGF) Internal. Example: Steroids |
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Clicker Question #4
An example of a transmitter that targets both ionotropic and metabotropic receptors: |
A. Acetylcholine
B. Dopamine C. Norepinephrine D. A and B E. A, B and C |
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Cyclic AMP As A 2nd Messenger
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Discovered in the liver
Investigations on the mechanism of epinephrine-induced glucose production in the liver A small molecule was discovered that could mimic the effect of epinephrine: cyclic AMP (cAMP) Found that epinephrine could produce an activation of cAMP synthesis via activation of adenylyl cyclase Enzyme assays revealed high level in the brain, with the prediction that this system would prove important in the central nervous system: Definitely Verified!! |
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NO Target
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Guanylyl Cyclase, the enzyme that makes cyclic GMP (cGMP)
In vascular smooth muscle, cGMP helps promote relaxation (vasodilation: increase in blood flow) cGMP normally broken down by a phosphodiesterase enzyme This enzyme is the target for Viagra inhibition increases blood flow and is used as a treatment for erectile dysfunction (1st oral drug to do this) |
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One Possible Role For Endocannabinoids:
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Retrograde Signaling
This could reduce the Input from another neuron |
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Clicker Question #5
The agent that signals the smooth ER to release calcium into the cytoplasm: |
A. Cyclic AMP
B. Cyclic GMP C. IP3 D. PIP2 E. DAG |
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SUMMARY
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Axoaxonic connections allow for one neuron to directly influence transmitter release from the terminal of a target neuron
Release can also be influenced by presynaptic autoreceptors Co-localization of 2 transmitters or a transmitter + a modulator is common |
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SUMMARY (Cont.)
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Two common receptor types are ionotropic (ligand-gated) and metabotropic
Two important signaling systems are mediated via (1) cyclic AMP and (2) PIP2 metabolism Signaling can also occur hormonally, as with the hypothalamic-pituitary axis (HPA) |