Muscle Contraction Flashcards
sarcomeres change ______ during muscle depolarization
length
The _____ segment of myosin has ATP and actin binding sites
S-1
the heavy myosin chains form the ____ region and the light myosin chains form the ______ region of the molecule
- tail
- globular head
myosin filaments form structures with 2 polypeptides in a ______ arrangement
alpha-helix (the tail region)
myosin heads project off of the thick filament every ____ degrees
60
_______: a 40 nm long fibrous protein that spans 7 G-actin myosin binding sites (inhibitory protein)
tropomyosin
during muscle relaxation, ______ is elevated out of the actin helical groove
tropomyosin
Ca++ binds to ______, which regulates the movement of tropomyosin
troponin
The Length-Tension Relationship states that force is proportional to __________
crossbridge overlap
___________: a single motor neuron and all of the muscle fibers it innervates
motor unit
a single motoneuron will innervate _________ to __________ muscle fibers
hundreds to thousands
the fibers of a single motor neuron are all __________ similar
biochemically
the ___________ describes the relationship between the number of muscle fibers innervated by a motoneuron and the degree of control exerted
innervation ratio
fine motor control occurs with a ____ fiber:neuron ratio and coarse motor control occurs with a _____ fiber:neuron ratio
- low
- high
skeletal muscle has a ________ type acetylcholine receptor
nicotinic
___________ or __________ can also activate muscle, but are inactivated more slowly than acetylcholine
- nicotine
- carbamylcholine
Muscle Action Potential (MAP) triggers conformational changes in the ______________ proteins
DHP/Ryanodine receptor-like proteins
normal muscle at rest should have ________ EMG activity
little/no
_________ is associated with the slowing of nerve conduction velocity
demyelination
__________ are disease states of the following cell types:
- cell bodies
- axons
- Schwann cells
- mixed
neuropathies
________ are disease states associated with the following structures:
- presynaptic - axon terminals
- synaptic cleft
- postsynaptic - sarcolemma
junctionopathies
_________ are disease states associated with the myofibers
myopathies
3 presynaptic muscle disorders
- hypocalcemia
- hypercalcemia
- botulinum toxin
______ is a presynaptic disorder marked by weakness, tetany, spontaneous EMG activity, and reduced acetylcholine release
hypocalcemia
________ is a presynaptic disorder marked by weakness due to continuous depolarization and spontaneous EMG activity (increased synaptic vesicle release)
hypercalcemia
______ causes a presynaptic disorder described as ‘functional denervation’. Presynaptic binding inhibits acetylcholine release.
botulinum toxin
3 post-synaptic neuromuscular disorders
- muscular dystrophy
- myasthenia gravis
- Conotoxin
_________: post-synaptic disorder caused by the lack of the structural protein dystrophin
muscular dystrophy
What condition is described by the following symptoms?
- leaky muscle cells, high creatine kinase levels
- progressive weakness
- EMG shows repetitive high frequency discharges
muscular dystrophy
_________: post-synaptic disorder in which acetylcholine receptors are destroyed (or genetically reduced in numbers)
Myasthenia gravis
What is the treatment for Myasthenia Gravis?
acetylcholinesterase inhibitors
In which condition is acetylcholine destroyed before it can become receptor bound?
Myasthenia Gravis
