Motor End Plate: Structure, Function & Neurotransmission Flashcards
What is the width of a synapse
200A or 20nm wide
What is formed between a skeletal muscle and the motor neurone that innervates it
Synapse
What is the term given to the number of muscle fibres innervated by a single motor neurone
Motor unit
What is the term given to the specialised portion of the sarcolemma of the muscle fibre innervated by a single motor nerve ending
Motor endplate
The terminal ending fits into a depression of the muscle membrane which is thrown into folds called ______
Palisades
What are the two components that make up the neurotransmitter Acetylcholine
Acetyl CoA, Choline
What is the name of the enzyme that facilitates the genesis of ACh
Choline Acetyltransferase
True or False, In the arrival of the nerve action potential, Ca 2+ voltage gated channels are opened in the terminal ending
True or False
True or False, Cholinergic neurotransmission is Ca2+ independent
False, it is dependent
What protein does Ca2+ ions bind to in the terminal endings
Calmodulin
What neurotransmitter does Ca2+ ions bind to in the active zones, signalling its release
Synaptotagmin
What is activated when Ca2+ binds to calmodulin
Ca2+-calmodulin kinase
What does kinase phosphorylate in the nerve action potential causing synaptic vesicles to be loosened from their cyto-skeleton attachments
Synapsin 1
What substance migrates and dock at the active zones
Synaptic vesicles
What protein is involved in docking, binding & endocytosis of the synaptic vesicle
Synaptotagmin
What is required for the fusion of synaptic vesicle to the Presynaptic membrane
SNARE proteins
What SNARE protein is described as a v-snare, vesicular membrane protein
Synaptobrevin
What snare proteins are described as a t-snare
Syntaxin, SNAP-25
What snare protein contains two plasma membrane proteins
SNAP-25
What Snare protein has small GTPase
Rab3
What snare protein is inactivated by Tetanus toxin & amp; Botulinum toxins B, D, F, G
Synaptobrevin
What SNARE protein is inactivated by Botulinum toxins C and A & amp; B, respectively
Syntaxin, SNAP-25
What toxin causes Spastic paralysis by blocking presynaptic neurotransmitter release in CNS
Tetanus
What toxin causes Flaccid paralysis by blocking ACh release at the n-m junction (Botox – achalasia, wrinkles)
Botulinum
What snare protein regulates a multi protein complex
Rab3
What snare protein may not be essential for docking or fusion
Rab3
What snare protein maintains normal reserves of SVs for accelerated exocytosis during repetitive stimulation
Rab3
What enzyme breaks down ACh into Choline and Acetate
acetylcholinesterase
How many vesicles do each nerve action potential release
60 vesicles
Approximately how many molecules of ACh does each synaptic vesicle contain
10,000
What is summated to form the muscle action potential
EPPs
True or False, Minute depolarizing spike potentials
True (Due to the spontaneous release of small quanta of ACh)
True or False, an increase Ca 2+ ions at the end plate cause an increase in the size of the potential
True
True or False, an increase Mg 2+ ions at the end plate cause an increase in the size of the potential
False, it is a decrease in Mg2+
Minature Endplate Potential produce muscle action potentials
False, it doesn’t
In Ca 2+ removal, Ca 2+ is exchanged with which ion
Na 2+
True or False. the removal of Ca 2+ is passive
False, it is active
True or false, the use of buffers is used in Ca2+ removal
True
What kind of disease id Myasthenia Gravis
Autoimmune Disease
The antibodies in Myasthenia Gravis destroys what type of receptors on the skeletal muscles
Nicotinic Receptors
What are the symptoms of Myasthenia Gravis
Weakness, Paralysis
What syndrome resembles Myasthenia Gravis, and decreases ACh release
Lambert- Eaton Syndrome
Antibodies in Lambert- Eaton Syndrome, work against which ion channel in the nerve endings at N-M junctions
Ca 2+
