Nueromuscloskeletal Flashcards
Acetycholinesterase
Breaks down acetylcholine to choline and acetate
Made by both muscles and neurons
Motor neuron and muscle communicate via activation of _____ on ____
Nicotinic acetylcholine receptors
Muscle cells
Choline Acetyltransferase
Synthesizes acetylcholine from choline + acetyl-CoA in the cytoplasm
Acetylcholine is transported into synaptic vesicles via ____
Acetylcholine/H+ antiporter
Proteoglycan that interacts with muscle specific kinase (MuSK) to trigger muscle cell to maintain clustered nicotinic acetylcholine receptors in area beneath neuronal contact
Agrin
Protein critical in formation of normal neuromuscular junctions and re-establishing neuromuscular junction following damage
Agrin
Kinase found in myocytes that helps with dispersal of nAChR clusters that have not been innervated by a motor neuron. ACh activation of nAChR helps to activate the kinase
Cyclin Dependent Kinase 5
Voltage gated Ca channels are localized ____
near the active zone in the presynaptic membranes
Endplate potential
Muscle cell response measured as local graded depolarization
Alpha subunits of nicotinic acetylcholine receptor
Binding of 2 ACh molecules –> channel open and increase membrane permeability to cations –> muscle membrane depolarization
Cholinergic agonists: binds to nAChR –> channel activation
Cause muscle spasms
Carbachol, nicotine
Blocks neuromuscular transmission by binding to nAChR, preventing ACh from binding and activating the receptor. Does not interact w/ voltage-gated channels involved in action potentials
Curare
Inhibit activity of acetylcholinesterase –> prolingation of endplate depolarization
Neostigmine, physostigmine, DFP
Prevents re-uptake of choline by presynaptic terminals and eventual depletion of releasable ACh –> paralysis
Hemicholinium-3
Subunit composition of adult nAChR
alpha2 beta gamma epsilon
Neuromuscular junction comprised of 3 cells
motor neuron
muscle fiber
Schwann cell
Ca2+ in the muscle is stored and released from ____
Terminal cisternae of the sarcoplasmic reticulum
Voltage gated Ca2+ channel that’s a voltage sensor on the T Tubule
Dihydropyridine receptor (DHPR)
Receptor on terminal cisternae of sarcoplasmic reticulum that is linked to dihydropyridine receptor on T tubule
Ryanodine receptor
Lets a lot of Ca out
Junctional tetrad is formed by
Dihydropyridine receptor and ryanodine receptor
SERCA
Ca2+ ATPase on SR membrane that pumps Ca2+ back into SR
Maintains low cytoplasmic concentration of Ca2+
Causes muscle relaxation
Calsequestrin
In sarcoplasmic reticulum
Low affinity but high binding capacity for Ca2+
Binds Ca2+ to keep [free Ca2+] low
Easily releases Ca2+ when concentration in lumen of cisternae decreases
Alignment protein of thick filaments
Titin
Alignment protein for thin filaments
Nebulin
Thin filament
Actin, tropomyosin, troponin
Thick filament
Myosin
Rigor mortis is caused when
myosin crossbridge stays bound to actin when depleted of ATP
Rate limiting step of crossbridge cycle
ADP release from myosin head
Myosin state(s) that have high affinity for actin
Unbound myosin
Myosin-ADP+P
Myosin state that has low affinity for actin
Myosin-ATP
Contraction where force is generated by muscle but no shortening of muscle fibers
Isometric contraction
Contraction where load is help constant and shortening of muscle fibers occurs
Isotonic contraction
Contraction where muscles relax against a load
Eccentric contraction
Troponin
Binds 4 Ca2+
Troponin T
Binds tropomyosin
Troponin C
Binds Ca2+
Troponin I
Binds actin
