Neuromuscular Junction — Flashcards

Flashcard 1: Stretch reflex:Activation of _____ motor neurons leads to direct contraction of the muscle

Answer: alpha

Flashcard 2: What type of muscle fibres do not have striations, troponin or T tubules?_____

Answer: Smooth muscle

Flashcard 3: Which nerve fiber afferents innervates all three muscle spindle fibres (dynamic nuclear bag, static nuclear bag, and nuclear chain fibers)?_____

Answer: Type Ia

Flashcard 4: The first step of muscle contraction occurs when the _____ neuron depolarizes, opens Ca2+ channels and ACh is released into the motor end plate.

Answer: somatic motor

Flashcard 5: A sustained contraction with little expenditure of energy is made possible by a _____ mechanism in smooth muscle

Answer: latching

Flashcard 6: Sympathetic stimulation (norepinephrine) of a smooth muscle produces _____ potentials and relaxation.

Answer: inhibitory (excitatory/inhibitory)

Flashcard 7: Chemical Events during Muscle Contraction: The **power stroke** is initiated by the release of _____ from the myosin head.

Answer: inorganic phosphate (Pi)

Extra: Sequence of chemical events in the cross-bridge cycle: 1. ATP binding: Myosin head detaches from actin. 2. ATP hydrolysis: Myosin head "cocks" into a high-energy state. 3. Cross-bridge formation: Myosin head binds to actin. 4. Power stroke: Release of inorganic phosphate (Pi) triggers the force-generating pivot. 5. ADP release: Occurs after the power stroke.

Flashcard 8: _____ is absent in smooth muscle but present in skeletal muscle

Answer: Troponin

Flashcard 9: Fast twitch muscle fibers are _____ due to decreased myoglobin concentration

Answer: white

Flashcard 10: After the power stroke in muscle contraction, binding of a new _____ molecule causes detachment of the myosin head from the actin filament

Answer: ATP