neurotransmitters 2 Flashcards

Neurotransmitter
Terms Definitions
GABA removal
transporters
histamine removal
transporters
neuropeptides removal
proteases
Norepinephrine--ß receptor--*Antagonist*
Propranolol
ACh--Muscarinic Receptor--*Antagonist*
Atropine
epinephrine synthesis
phenylalanine-N-methyltransferase (cytoplasmic) converts NE to E - NE needs to exit vesicle, convert, come back
GABA post-synaptic effect
inhibitory
GABA post-synaptic effect
inhibitory
Dopamine
Influences movement, learning, attention, and emotion. Excess= schizophrenia. Not Enough= Parkinson's.
Ach removal
degraded by acetylcholinesterase
glycine vesicles
small clear-core vesicles
Muscarine
agonist at muscarinic Ach
serotonin vesicles
large dense-core vesicles
Acetylcholine
Central Nervous system, excites muscles, inhibits heart, most common neurotransmitter
Glutamate
A major excitatory neurotransmitter; involved in memory
DOPA decarboxylase
coverts DOPA to dopamine
GABA storage vesicles
small clear-core vesicles
Cuarare
antagonist at nicotinic Ach receptors
Norepinephrine
Helps control alertness and arousal. Not enough= slight depression.
ACh inactivation
1. ionotropic receptors desensitize rapidly2. enzymatic degradation by acetylcholine esterase in synaptic cleft - resulting choline taken up by pmCholine transporter3. no reuptake transporter for ACh
Serotonin is what type of neurochemical?
Indolamine
neuropeptides properties
post-synaptic effects are excitatory and inhibitory

precursors are amino acids

rate-limiting steps are synthesis in neuronal cell body and ATP-dependent fast axonal transport to nerve terminal

removal is by proteases

vesicles are large dense-core vesicles
Oversupply of Glutamate
Can cause migraines and seizures
which neurotransmitters have inhibitory post-synaptic effects?
GABA and glycinesometimes neuropeptidesall others have excitatory post-synaptic effects
Effects of Epinephrine
Also called adrenalin-transmitter in the CNS-Produced by adrenal medulla & released into blood stream to enhance arousal.
Ach synthesis rate-limiting step
CAT (choline acetyl transferase)
what is the most common inhibitory NT in PNS?
glycine
sources of monoamines
1. dopamine: midbrain2. NE: pons (locus ceruleus)3. E: adrenal medulla4. serotonin: midline nuclei of pons and medulla5. histamine: hypothalamus6. ACh: nuclei in pons and lower frontal lobe, cranial nerves and spinal motoneurons, sympathetic and parasympathetics
Effects of Norepinephrine
Involved in the control of alertness/wakefulness-found in neurons in the ANS and in the brainNE neurons in the brain produce inhibitory postsynaptic potentials-NE neurons outside the NS usually have an excitatory effect.
where is NE found?
CNS and postganglionic and sympathetic cytosolic cells which release EPI stimulated by corticosteroids
name the 5 biogenic amines
the catecholamines: dopamine; epi; norepiserotoninhistamine
how do you decrease cAMP in target cells?
inhibit adenylate cyclase
general characteristics of catecholamines
1. synthesized by small percentage of neurons but wide distribution of terminals in brain2. excitatory, inhibitory, modulatory3. all synthesized by tyrosine or indirectly from phenylalanine via PAH4. one type of vesicular transporter in brain for all; another type in adrenal medulla. both inhibited by reserpine5. all receptors are metabotropic6. major mechanism for stopping action is reuptake - pm dopamine and pm NE/E transporters7. degraded by 2 enzymes: MAO and COMT
What are the Blocking Agents of Ach (muscarinic)?
1)atrophine2)scopolamine->blocks ANS activity
how do you increase DAG, IP3, and Ca in target cells?
stimulate phospholipase C
what is the function of electrical synapses? give examples
synchronize electrical activity among populations of neuronsbrainstem neurons - breathinghormone-secreting neurons: all cells fire action potential at the same time to release a burst of hormone into the circulation - mammary glandscoordinated intercellular signaling and metabolism (glial cells form large interconnected networks)
name 4 components of neurotransmitter removal from synaptic cleft
1. diffusion away from post-synaptic receptors

2. re-uptake into pre-synaptic nerve terminal by transporter proteins

3. uptake into nearby glial cells

4. degradation by specific enzymes
name 3 places where muscarinic Ach receptors are important
1. forebrain2. ganglia of PNS3. autonomic effector organs: heart; smooth muscle; exocrine glands
give 3 examples of blockers of muscarinic Ach receptors that have therapeutic value
1. atropine - pupil dilation

2. scopolamine - prevent motion sickness

3. ipratropium - treats asthma
where does the choline for Ach synthesis come from?
choline is present in the plasma at high concentrationsit is taken up into the pre-synaptic neuron by a Na-dependent choline transporter
glutamate precursors
glutamine
glycine removal
transporters
histamine precursor
histidine
Glutamate--NMDA receptor--*Antagonist*
AP5
serotonin removal
transporters, MAO
serotonin post-synaptic effect
excitatory
serotonin post-synaptic effect
excitatory
Malfunction of Norepinephrine
Depresses mood
what enhances EPI synthesis?
cortisol
histamine properties
excitatory post-synaptic effectprecuror is histidine and rate-limiting step is histidine decarboxylaseremoval is by transportersvesices are large dense-core vesicles
glutamate synthesis rate-limiting step
glutaminase
histamine properties
excitatory post-synaptic effect

precuror is histidine and rate-limiting step is histidine decarboxylase

removal is by transporters

vesices are large dense-core vesicles
scopolamine
prevents motion sicknessblocker of muscarinic Ach receptor
MAO
dopamine catabolism enzyme contained in both neurons and gliamonoamine oxidaseinhibited by antidepressants
Alzheimers
Degnerative loss of cognitive capacity resulting in part due to a deficit in acetycholine (Ach).
Steroid hormones
Steroid hormones are lipophillicderived from cholesterol
Ach storage vesicle
small clear-core vesicle
WHICH IS EXCITATORY?
NICOTINIC (EXCIT)MUSCARINIC (INHIB)
where is EPI found
adrenal medulla and brain stem
MAOb
1. CNS2. substrate - prefers B-phenylethylamine3. irreversibly inhibited by selegiline
DEPRESSION IS ASSOCIATED WITH LOW:
AND HIGH:
how is ACh terminated?
choline esterases terminate transmission
alpha-bungarotoxin
binds to nicotinic Ach receptors at neuromuscular junctions but not at neuronal junctions
Effects of Serotonin
Usually produces an inhibitory affect. Implicated in mood, eating behavior, sleep, agressive behavior & pain regulation.
WHICH NT'S ARE CATECHOLAMINES?
NE, E, AND DA
where are cell bodies of EPI found?
substantia nigra
storage in vesicles
1. assembled in terminal through endocytosis2. NTs enter vesicles using transporter proteins in vesicular membrane3. depends on vesicular ATPase that exchanges H+ for NTs4. reserpine blocks transporter
what are the inhibitors of acetylcholinesterase?
organophosphates, e.g. Sarin
what are the agonists of nicotinic receptors?
ACh, nicotine, Carbuchol
Lymbic System
Causes release of CRH in response to stressful situations
what agents releases vesicles and depletes amoutn of ACh for future use?
Beta-byngarotoxin and black widow spider venom
describe the differences in synthesis, storage, and transport between small molecule neurotransmitters and peptide neurotransmitterslocation of synthesistransportvesicles
enzymes needed to synthesize small molecule neurotransmitters are produced in the neuronal cell body and transported to the nerve terminal by slow axonal transportprecursor molecules are taken into the cell by transporter proteinssmall molecule neuropeptides are synthesized at the nerve terminal and stored in small clear-core synaptic vesiclesneuropeptides are synthesized in the cell body of the neuron and transported to the nerve terminal by fast axonal transportneuropeptides are transported and stored in large dense-core vesicles
Effects of Glutamic Acid (Glutamate)
Believed to be 1st neurotransmitter to evolve-excitatory and inhibitory affects on axons, raising or lowering threshold of excitation thus affectrate at which action potentials occur-principle excitatory transmitter in the brain-brain contains several types of glutamate receptors, most of them metabotrophic and control sodium channels
what do the effectors of nicotinic receptors tend to be?
conductance pores b/c nicotinic receptors tend to be part of larger proteins which form channels in membranes
what are the two types of neurotransmitter receptors and how do they differ?distinguish between both speed and duration of post-synaptic response
ionotropic receptor = ligand-gated ion channel = molecule that is both receptor and ion channel allows fast post-synaptic response that lasts only a short timemetabotropic receptor = molecule that is a receptor only, not an ion channel allows slower post-synaptic response that persists for a longer time
describe the differences in synthesis, storage, and transport between small molecule neurotransmitters and peptide neurotransmitters

location of synthesis
transport
vesicles
enzymes needed to synthesize small molecule neurotransmitters are produced in the neuronal cell body and transported to the nerve terminal by slow axonal transport

precursor molecules are taken into the cell by transporter proteins

small molecule neuropeptides are synthesized at the nerve terminal and stored in small clear-core synaptic vesicles

neuropeptides are synthesized in the cell body of the neuron and transported to the nerve terminal by fast axonal transport

neuropeptides are transported and stored in large dense-core vesicles
How many different types of neurotransmitters exist?
There are approx. 60 different types of neurotransmitters.
what are the two types of neurotransmitter receptors and how do they differ?

distinguish between both speed and duration of post-synaptic response
ionotropic receptor = ligand-gated ion channel = molecule that is both receptor and ion channel allows fast post-synaptic response that lasts only a short time

metabotropic receptor = molecule that is a receptor only, not an ion channel allows slower post-synaptic response that persists for a longer time
where does the choline for Ach synthesis come from?
choline is present in the plasma at high concentrations

it is taken up into the pre-synaptic neuron by a Na-dependent choline transporter
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