05 The Muscular System Free Online FlashCards

What are the main functions of the muscular system?

It produces movement, maintains posture, stabilizes joints, and generates heat.

Where is skeletal muscle found, and what does it do?

Skeletal muscle is usually attached to bones by tendons. It is mostly voluntary and moves the skeleton, helps maintain posture, and produces heat.

Where is cardiac muscle found, and what is its function?

Cardiac muscle is found in the heart wall. It contracts involuntarily and rhythmically to pump blood.

Where is smooth muscle found, and what does it do?

Smooth muscle lines hollow organs and blood vessels. It involuntarily moves substances and adjusts the diameter of passageways.

Which muscle types are striated, and why?

Skeletal and cardiac muscle have visible striations because their contractile proteins are arranged in repeating patterns. Smooth muscle lacks this striped appearance.

How does the sliding-filament action shorten a sarcomere?

Myosin pulls actin inward, making the filaments slide past one another. The filaments themselves do not shorten; sarcomeres shorten.

What starts the contraction signal in a skeletal muscle fiber?

At the neuromuscular junction, a motor neuron releases acetylcholine, triggering an electrical signal in the muscle fiber that leads to calcium release.

What role does calcium play in skeletal muscle contraction?

Calcium exposes binding sites on actin, allowing myosin to attach and pull.

How does ATP support the actin–myosin cycle?

Myosin uses energy from ATP to repeat its pull-and-release cycle on actin.

Can a muscle produce force without visibly shortening?

A muscle can generate force while maintaining nearly the same length, such as when holding a heavy bag still.

How do tendons help skeletal muscles move the body?

Tendons transmit muscle force to bones. The pull moves bones around joints.

What is an agonist muscle?

The agonist, or prime mover, produces the main force for an action.