Sliding Filament Theory

What initiates the contraction within a muscle fiber in the Sliding Filament Theory?

Increased calcium in the fiber.

What binds to troponin on thin filaments during muscle contraction?

Calcium.

In the process of muscle contraction, what happens to the sarcomere?

The entire sarcomere becomes shorter.

What is released from the myosin head after the power stroke?

ADP and P.

What is the role of ATP in muscle contraction?

ATP binds to the myosin head, providing energy to detach the crossbridge.

What maintains the muscle contraction if calcium is still present in the fiber?

Continuous formation of crossbridges.

What is the structure that separates individual sarcomeres?

Z discs/Z line.

What happens to the I band during muscle contraction?

The I band gets smaller.

What does the M line represent in a sarcomere?

The midline of the sarcomere.

What is the relationship between a motor neuron and a muscle fiber?

One motor neuron innervates one muscle fiber, forming a motor unit.

What happens at the neuromuscular junction?

The motor neuron meets the sarcolemma of the muscle fiber.

What is the H zone and what happens to it during contraction?

The H zone is the space between actin within one sarcomere, which disappears when the muscle is fully contracted.

What does the term 'power stroke' refer to?

The action of myosin heads pulling on actin during muscle contraction.