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WorksheetsMotor Unit and Muscle Contraction Quiz
Total questions: 20
Worksheet time: 10mins
What is a motor unit?
A group of neurons
A single neuron
A motor neuron and the muscle fibers it innervates
A group of muscle fibers
Which principle explains the increasing activation of motor units?
All or None law
Recruitment
Reflex arc
Wallerian degeneration
What is the site of synapse between a motor neuron and muscle fiber?
Synaptic cleft
Motor end plate
Myofibril
Axon hillock
Miniature End Plate Potentials are due to?
Action potentials
Random leakage of Na+
Spontaneous release of ACh vesicles
Muscle fatigue
Which structure stores and releases calcium for contraction?
T-tubule
Myofibril
Sarcoplasmic reticulum
Nucleus
Which part of sarcotubular system carries action potential into the fiber?
Sarcoplasmic reticulum
T-tubule
Nucleus
M-line
Which is a congenital disorder affecting NMJ?
Parkinsonism
Myasthenia Gravis
Alzheimer’s disease
Multiple sclerosis
Botulinum toxin blocks which step?
ACh release
ACh receptor binding
Calcium reuptake
ATP binding
Which enzyme degrades acetylcholine in NMJ?
ATPase
Acetylcholinesterase
Myosinase
Phosphorylase
Which of the following occurs during rigor mortis?
ATP increases
Muscles relax completely
No crossbridge formation
ATP is depleted
What is a characteristic of red (type I) muscle fibers?
Fatigue rapidly
Fast twitch
Rich in myoglobin
Large diameter
White (type II) fibers are suited for?
Endurance
Posture
Quick bursts of activity
Sustained contraction
Which muscle fiber type shows slow oxidative metabolism?
Type I
Type IIa
Type IIb
All muscle fibers
Which is NOT true about red fibers?
Slow twitch
High myoglobin
Low mitochondria
Rich blood supply
What is the role of ATP in contraction?
Initiates calcium release
Binds actin
Detaches myosin from actin
Causes depolarization
What happens when ATP is not available in muscle?
Tetanus
Rigor mortis
Fatigue
Cramp
Isometric contraction involves?
Shortening of muscle
Change in joint angle
No shortening but tension generation
Free movement
Which is an example of isotonic contraction?
Holding a plank
Wall sitting
Lifting a dumbbell
Pushing against a wall
Which contraction has constant length?
Isometric
Isotonic
Eccentric
Concentric
Which contraction maintains constant tension?
Isometric
Isotonic
Isokinetic
Reflex
