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NMJ
NMJ
?
Reflexes
Reflexes
100
The lower motor neuron exits through which "horn"?
What is the anterior/ventral horn
100
The "Electrical" component of excitation-contraction coupling is....?
What is the propagation of an action potential through the muscle
100
What vitamin is required in order for proper acetylcholine synthesis?
What is Vitamin B5 aka Pantothenate (ACh=Acetyl CoA+choline; need Vit B5 for AcetylCoA synthesis)
100
Nuclear bag fibers are sensitive to __________ of stretch. Nuclear chain fibers are sensitive to __________ of muscle fiber.
What is Velocity, Length
100
(1a,b)What is the function of the extrafusal muscle fiber? the intrafusal muscle fiber? 2)What is another name for the intrafusal muscle fiber? 3)What are its two components
1a)muscle contraction 1b)sensory, afferent 2)muscle spindle 3)Nuclear bag fibers (group 1A afferents) & Nuclear chain fibers (group II afferents)
200
Where is acetylcholine synthesized, what breaks it down in the synaptic cleft, and which breakdown product is reabsorbed/recycled by the presynaptic terminal?
What is cytosol, acetylcholinesterase, choline
200
The "Chemical" component of excitation-contraction coupling is.....?
What is the release of Ca2+ from the sarcoplasmic reticulum
200
List the relative diameter size, conduction velocity, and presence/absence of myelination for: -Type Ia nerve fiber -Type II nerve fiber
Type Ia: largest, fastest, yes Type II: medium, medium, yes
200
Through which "horn" do the Type Ia & II nerve fibers enter the spinal cord? What type of connection does Ia afferent make with alpha motoneuron for a muscle?
What is Posterior/Dorsal horn, monosynaptic
200
The Stretch Reflex, aka __________ reflex, or _________ reflex, receives an afferent signal through Type _____ nerve fiber, activated with a muscle _________ of the muscle __________.
myotatic reflex, or knee-jerk reflex; Type 1a nerve fiber, stretch, spindle
300
Where is acetylcholine packaged and what protein is responsible for its vesiculation?
What is Golgi apparatus, Clathrin
300
The "Mechanical" component of excitation-contraction coupling is.....?
What is the development of tension in the muscle fiber, movement of myosin-actin crossbridges
300
In a Stretch Reflex, a signal from the alpha-motorneuron will stimulate a... + or - synapse to alpha-motorneuron? + or - synapse to synergistic muscles? + or - synapse to interneuron? + or - synapse from interneuron to antagonistic muscles?
+ (excitatory) synapse to a-motorneuron + synapse to synergistic muscles + synapse to interneuron - (inhibitory) synapse from interneuron to antagonistic muscles
300
The Golgi Tendon Reflex, aka the clasp-knife, is stimulated by muscle _________, which is sensed by the ____ ____ organ which is located at the ______________ junction.
Contraction; Golgi tendon organ; musculotendinous junction
300
The Golgi Tendon Reflex is activated by a signal from the Type ___ afferents, through contraction of the agonist muscle. This stimulates... + or - to interneurons? + or - synapse from interneuron to alpha-motorneuron? + or - synapse from interneuron to synergistic muscles? + or - synapse from interneuron to antagonistic muscles?
Ib + synapse from 1b to interneurons - synapse from interneuron to a-motorneuron - synapse from interneuron to synergistic muscles + synapse from interneuron to antagonistic muscles
400
How many subunits in the nAChR and how many ACh need to bind in order to cause a conformational change leading to opening?
What is 5 subunits, 2ACh
400
Why do pt's with Myasthenia Gravis experience muscle weakness/failure? What tx is typically used and why?
Their body produces antibodies that block or destroy their own nAChR. So, end plate potentials are not strong enough to open the voltage-gated Na+ channels, thus, no depolarization of the sarcolemma, no release of Ca2+, no muscle contraction. Neostigmine, an AChE Inhibitor is used for tx to maintain high levels of ACh in the synaptic cleft to compete with antibodies for binding on the nAChR.
400
How does Botulinum toxin cause paralysis of muscles? How does black widow venom cause muscle spasms & pain?
Botulinum toxin causes failure of presynaptic vesicles to dock at the membrane & release ACh into NMJ; due to loss of synaptosomal-associated protein (SNAP), a docking protein. Black Widow venom component Latrotoxin forms pores in the lipid membrane, releasing & depleting all ACh vesicles in the presynaptic terminal, resulting in loss of ability to recycle ACh vesicles.
400
Muscle spindles and Golgi tendon organs are considered mechanoreceptors and have _________-activated ion channels. These channels are located on a neuron's plasma membrane, open in response to a __________ stimulus and convert it into an __________ signal through a membrane potential change (via ionic flow).
Stretch-activated ion channels; mechanical stimulus; electrical signal
400
The Flexor-withdrawal Reflex is mediated by Type ____ nerve fibers which are on the Nuclear ________ fibers They are stimulated in response to pain & temperature, which causes withdrawal on the ___________ side, and extension on the ________ side for support.
Type II afferents; Chain fibers ipsilateral side; contralateral side.
500
As an action potential is propagating through the presynaptic terminal, what are the 6 following steps that lead to choline reuptake?
What is 1)opening of VDCC & influx of Ca2+, 2)release of ACh into synaptic cleft, 3)binding of ACh to nAChR on motor end plate, 4)opening of nAChR & influx of Na+ & efflux of K+, 5)depolarization of motor end plate, 6)ACh breakdown by AChE (into Acetate & Choline...)
500
Give an example of a drug/chemical that: -mimicks ACh -blocks choline uptake -stops ACh release -inhibits AChE -blocks the ACh receptor
What is -nicotine, -hemicholinium, -botulinus toxin, -neostigmine, -succinylcholine
500
Why do Cisplatin and Paclitaxel, used in cancer tx, lead to muscle weakness?
These drugs disrupt microtubule function by polymerizing them, thus blocking mitosis of cancerous cells. But this polymerization of microtubules prevents synaptic vessels from moving from the cytosol to the presynaptic terminal for ACh release.
500
In the Flexor-withdrawal Reflex, the Type II (&III, IV) nerve fibers stimulate... + or - synapse to interneurons? + or - synapse from interneuron to ipsilateral extensor muscle? + or - synapse from interneuron to ipsilateral flexor muscle? + or - synapse from interneuron to contralateral extensor muscle? + or - synapse from interneuron to contralateral flexor muscle?
+ synapse to interneurons - synapse fro interneuron to ipsilateral extensor + synapse from interneuron to ipsilateral flexor + synapse from interneuron to contralateral extensor - synapse from interneuron to contralateral flexor
500
Gamma motoneurons are controlled by the ___________ tract, originating in the __ _____, and they change the _________ of the muscle spindles, and thus control _______ sensitivity. Gamma motoneurons are _________ nerve fibers, thus their cell bodies are located in the _______ horn of the spinal cord. The Static gamma synapse at the Nuclear _____ fiber while the Dynamic gamma synapse at the Nuclear ______ fiber.
Rubrospinal tract; Red Nucleus; Sensitivity; Reflex Efferent nerve fibers; anterior/ventral. Static gamma-->Nuclear Chain fibers Dynamic gamma--> Nuclear Bag fibers