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Neurotransmitters Test 2

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ilm1993's version from 2018-02-08 23:14

Synapse Anatomy

Question Answer
Synaptic CleftThe cell membranes of the two cells are actually separated by a small space
The cell membrane of the axon terminal is called thepresynaptic membrane.
The axon terminal can also be referred to as asynaptic terminal
The presynaptic terminal contains membrane bound vesicles that contain neuroactive molecules calledneurotransmitters.
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Synaptic Potentials

Question Answer
When the neurotransmitter binds to its receptor on the postsynaptic membranespecific ion channels open.
Excitatory Post Synaptic Potential (EPSP)membrane potential has been moved closer to threshold making it more likely that the cell will have an action potential.
Inhibitory Post Synaptic Potential (IPSP)the membrane potential has been moved further away from threshold making it more unlikely that a cell will have an action potential.
Transmitters that depolarize the cell areexcitatory
Transmitters that hyperpolarize the cell areinhibitory.
Temporal summationwhen postsynaptic potential summate over time. A second PSP occurs before the first has decayed.
Spatial summationwhen PSPs summate over the surface of the cell membrane because they overlap
Postsynaptic potentials (EPSPs and IPSPs) can add together orsummate.
If the postsynaptic potentials summate so that threshold is crossedan action potential will occur in the postsynaptic cell.
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Action Potential in a synaptic transmission

Question Answer
When an action potential occurs in the first cell itreleases neurotransmitters from its axon terminals.
Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on thepostsynaptic membrane
Where Ca comes in arevoltage gated channels.
Where neurotransmitters come in arechemically gated channels.
The binding of the neurotransmitter to its receptor causes a change inmembrane permeability to specific ions
1When the action potential travels into the axon terminal it causes the axon terminal to become depolarized.
2The presynaptic membrane contains voltage-gated Calcium channels that open when the terminal becomes depolarized.
3The concentration of calcium is higher in the extracellular fluid that it is inside the terminal. When the calcium channels open, calcium moves down its concentration gradient and enters the terminal.
4Ca channels opening causes the synaptic vesicles to fuse with the presynaptic membrane, dumping their contents into the synaptic cleft.
5The neurotransmitter binds to receptors on the postsynaptic membrane.
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Different types of synapses

Question Answer
Axosomaticsynapse between an axon from one cell and the cell body (soma) of another cell.
Axodendriticsynapse between an axon from one cell and a dendrite of another cell
Axoaxonicsynapse between an axon of one cell and the axon of another cell
Neuromuscular junctionmotor neuron and skeletal muscle
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Criteria to be a neurotransmitter:

Question Answer
1the machinery to make the molecule must exist in the cell (synthesis)
2must be present in the cell
3must be releasable from the terminal
4there must be a mechanism to turn the transmitter off. This can be accomplished by enzymes.
Neurotransmitter are able to transfer into another cell vialock and key.
The action of a neurotransmitter is dependent onthe receptor.
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Acetlycholine

Question Answer
Cells that release Acetylcholine are calledcholinergic.
Acetylcholine binds tonicotinic receptor and muscarinic receptors
Acetylcholine can beinhibitory or excitatory.
The enzyme that breaks acetylcholine down is calledacetylcholinesterase
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Norepinephrine and epinephrine

Question Answer
Cells that release norepinephrine is calledAdrenergic,
Norepinephrine and epinephrine belongs to a class of molecules calledCatecholamines.
Norepinephrine binds toalpha and beta receptors.
Norepinephrine is Broken down by the enzymes calledmonoamine oxidases (MAO)
Base structure of norepinephrine and epinephrinetyrosine
MAO Blockers blockersNorepinephrine goes up
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Serotonin

Question Answer
Serotonin is found incentral nervous system
Serotonin is Involved indepression and sleep.
SSRIdrugs that block re-uptake. Serotonin increases. Side effect include sleep disorders and a lack of sex drive
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Dopamine

Question Answer
Dopamine is found inthe CNS
Dopamine is involved inParkinson’s disease, movement disorders’s, and the brains system mechanism for reward
Lack of dopamine can lead toParkinson. May be involved with Schizophrenia
Dopamine can contribute toaddictive behaviors
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Glutamate

Question Answer
Glutamate is the most Predominateexcitatory transmitter in the central nervous system.
Glutamate is Responsible forbrain cell death after stroke, trauma, seizures.
Glutamate cankill cell’s mitochondria due to its excitatory potential
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GABA

Question Answer
GABA isa predominant inhibitory transmitter in the central nervous system
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Neuromuscular Junction

Question Answer
Every muscle fiber is innervates withone terminal.
In a neuromuscular junction, there istemporal summation
1Action potential travels down axon to the terminal. Sodium and calcium and going down the axon terminal.
2Calcium (voltage gated) channels open. Calcium will bind to the Ach Vesicles. The vesicles will the attracted axon terminal membrane. Is become one continuous membrane via exocytosis.
3Dumps contents out into synaptic cleft. Post synaptic membrane has nicotinic acetylchloline receptors. Lets sodium come into the cell via voltage gated calcium release. The sodium that enters the muscle cell creates the action potential. Travels down the muscle fiber to the T tubule.
5It goes in the sarcoplasmic reticulum and it releases calcium inside the cell, which binds to the triponin, which pulls the tropomyosin out of the groove.
6Then neurotransmitter binds to receptors on cell membrane of muscle cell = Motor end plate (Post synaptic membrane).
7Acetylcholinesterase break down ACH
Muscles are connected viagap junction
Myasthentia gravisautoimmune disease that destroy the receptors for acetylcholine. You can treat this by filtering the blood and draining antibodies
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Lobes in brain

Question Answer
Lobes in the brainFrontal, Parietal, Occipital, Temporal
Frontalfront of the brain, responsible for personality traits, abstract thought and motor function. Motor function localized in primary motor cortex, which is found in the precentral gyrus
Parietalseparated from the frontal lobe by the Central Sulcus – responsible for somatosensory function which is found in the postcentral gyrus
Temporallower half of the cortex – responsible for: speech, memory, learning, hearing
Occipitallocated at the back of the brain – responsible for vision
Thalamusmajor sensory relay center- sends sensory information to the correct areas of the cortex where sensation is perceived. Will direct it to the correct place in the cortex
Hypothalamuslies below the thalamus – controls autonomic function as well as hormonal secretions from the pituitary gland.
Basal gangliacontrols secondary motor movements – area associated with Parkinson’s disease
Brainstemvegetative function – respiration, heart rate – life supporting functions that we don’t think about but never the less occur
Spinal CordCervical, thoracic, lumbar, sacral
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The central nervous system is divided into

Question Answer
the neocortexcerebral cortex
the cerebellumhas as much neurons as the cortex
DiencephalonThalamus, hypothalamus, Basal ganglia (caudate, putamen, globus pallidus)
Brain stemmidbrain, pons, medulla oblongata
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Spinal chord

Question Answer
Cervical8
Thoracic12
Lumbar5
Sacral5
spinal nerves31 pairs
Spinal nerves sends messagesinto the CNS (brain). (Ascending)
Motor Nerves send messagesaway from the CNS. (Descending)
Middle of spinal cord isgrey matter
Outside of spinal cord is awhite matter
Ventral hornwhere motor neurons are located
Dorsal root gangliaa sensory neuron whose axon originated in the skin
Dorsal rootsensory axons that are sent up the chord
Mixed chordhave both motor and sensory neuron
You can create an action potentialanywhere
Sensory neurons have receptors inskins
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ANS

Question Answer
Autonomic nervous systemTakes care the the thing that you do not think about; takes care of involuntary things
What controls the Autonomic Nervous Systemthe hypothalamus
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Sympathetic

Question Answer
LocationT1 to L2 have cells called the intermediolateral cell column. its is where the cell bodies of the 1st neuron of the sympathetic nervous system is located. They are going to send their impulses out through the ventral root.
Gangliapart of the PNS. They will send their axons out into the ventral root and they make a synapse of cells in the ganglia.
In ANSthere’s going to be two neuronsone going from the chord to the ganglia, and one from the ganglia to the organs
The first neuron has ashort axon. Leaves spinal cord and travels through spinal or somatic nerves to synapse on one of the ganglia (most located in the paravertebral chain ganglia)
1st neuronPre-ganglionic neuron. Sympatheic nervous system. Cell bodies are in the intermedial cell column and axons are going to synapse on neurons in the ganglia. Going to release acetylcholine and had a nicotinic receptor. Goes through ventral root and goes into spinal nerves.
2nd neuronPost ganglionic neuron. Going to release Norepinephrine and the receptor is alpha or beta.
sympathetic system will increaseheart rate and increase the strength of the heart’s contraction it will decrease gastric motility
norepinephrine causesvasoconstriction
epinephrine causesvasodilation of the smooth muscle in the bronchioles of the respiratory tree
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Parasympathetic

Question Answer
LocationIn brain stem and sacral cord. They are exiting via crania nerves.
1st neuron havelong axons because they don’t have ganglions. Going to synapse tot he walls of the organs that they want to control.
Preganglonic fibers (first neuron) travelsfrom the brain stem through cranial nerves to synapse
The first nerve fiber isvery long and the second nerve fiber is very short
Acetylcholine isthe neurotransmitter at both synapses in the parasympathetic system
The receptors at each synapse differnicotinic at the first, muscarinic at the second
In many cases the action of the parasympathetic system isopposite to that of the sympathetic system
Activation of the parasympathetic system willslow the heart
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