Neuromuscular Junction and Muscle Contraction

Flashcards about key concepts related to the neuromuscular junction and muscle contraction.

Neuromuscular Junction

The site where a motor neuron and a muscle fiber meet.

Acetylcholine

The neurotransmitter released from the motor neuron at the neuromuscular junction.

Membrane Potential Change

The binding of acetylcholine to receptors on the muscle fiber causes a change in membrane potential, leading to muscle contraction.

Sodium Ions

The ion that flows into the muscle fiber to initiate an action potential after acetylcholine binds to its receptors.

Sarcoplasmic Reticulum

The structure from which calcium is released in the muscle fiber during an action potential.

Troponin

The protein in the muscle fiber that calcium ions bind to in order to initiate muscle contraction.

Sliding Filament Model

The model that explains muscle contraction as actin and myosin filaments sliding past each other.

H Zone

The region of the sarcomere that disappears during muscle contraction.

I Band

The part of the sarcomere that shortens during contraction according to the sliding filament model.

Cross-Bridge

The term for the binding of myosin head to actin.

Power Stroke

The event in muscle contraction when myosin releases ADP and phosphate.

ATP

The molecule required for the detachment of the myosin head from actin.

Calcium Ions

The ion that is pumped back into the sarcoplasmic reticulum during muscle relaxation.

T-Tubules

The structures that transmit the action potential to the interior of the muscle fiber.

Tropomyosin

The protein that prevents the binding of myosin to actin in relaxed muscle.

Calcium Regulation

Myosin’s ability to bind to actin is regulated by the presence of calcium.

Energy for Myosin Movement

The primary role of ATP in muscle contraction.

Calcium Increase Effect

Binding of calcium to troponin causing a conformational change in tropomyosin during muscle contraction.

Synaptic Cleft

The part of the neuromuscular junction that is the gap between the motor neuron and the muscle fiber.

Function of T-Tubules

Their primary function is to transmit the action potential to the interior of the muscle fiber.

Acetylcholine Binding Effect

An action potential is generated on the muscle fiber immediately after acetylcholine binds to receptors.

Oxygen's Role in Muscle Contraction

Oxygen is essential for ATP synthesis but does not play a direct role in muscle contraction.

Muscle Contraction Cycle Requirement

The cycle repeats as long as ATP is present and calcium is bound to troponin.

Primary Function of Sarcoplasmic Reticulum

To store and release calcium ions in muscle cells.