Muscle Contraction Steps Quiz

Questions and Answers

What occurs in Step 1 of muscle contraction?

Myosin and actin bind

Acetylcholine is released

Nerve impulse reaches neuromuscular junction (correct)

Sodium channels open

What neurotransmitter is released by the motor neuron in Step 2?

Acetylcholine (ACH)

In Step 3, ACH binds to muscle receptor sites.

True

What happens to sodium channels in Step 4?

They open Signup and view all the answers

What creates the action potential in Step 5?

Na+ influx Signup and view all the answers

The action potential travels down the muscle cell in Step 6.

True Signup and view all the answers

What does the release of Ca++ cause in Step 7?

Ca++ is released into the cell and around sarcomere contraction units. Signup and view all the answers

How do Ca++ ions influence myosin and actin in Step 8?

They allow binding Signup and view all the answers

What does the myosin do during contraction in Step 9?

Myosin heads pull actin filaments toward the center. Signup and view all the answers

What happens when the action potential ends in Step 10?

Muscle relaxes Signup and view all the answers

Study Notes

Steps of Muscle Contraction

Nerve Impulse reaches the neuromuscular junction, triggering muscle activation.
Motor neuron releases Acetylcholine (Ach), a neurotransmitter, into the synaptic gap, facilitating communication between nerve and muscle cells.
Ach binds to muscle receptor sites, initiating the muscle contraction process.
Binding of Ach stimulates receptors, leading to the opening of sodium (Na+) channels in the muscle cell membrane.
Influx of Na+ ions alters the cell's polarity, generating an electrical current known as an Action Potential.
The Action Potential travels along the sarcolemma, spreading across the muscle fiber to initiate contraction.
The Action Potential triggers the sarcoplasmic reticulum to release stored calcium ions (Ca++) into the muscle cell and surrounding sarcomeres.
Increased Ca++ levels enable myosin heads to attach to actin filaments within the sarcomeres, forming cross-bridges essential for contraction.
Myosin heads pull actin filaments towards the center of the sarcomere, resulting in sarcomere shortening and muscle contraction.
When the Action Potential ceases, Ca++ is reabsorbed by the sarcoplasmic reticulum, allowing myosin and actin to return to their original positions, leading to muscle relaxation.

Description

Test your knowledge on the 10 steps of muscle contraction with this quiz. Each step includes key processes involved in how muscles respond to nerve impulses. Perfect for students of biology or anatomy.