Muscles: Why are they important?

Muscles and nerve fibers allow a person to move their body and enable the internal organs to function.

There are more than 600 muscles in the human body. A kind of elastic tissue makes up each muscle, which consists of thousands, or tens of thousands, of small muscle fibers. Each fiber comprises many tiny strands called fibrils.

Impulses from nerve cells control the contraction of each muscle fiber. A muscle’s strength depends mainly on how many fibers are present.

To fuel a muscle, the body makes adenosine triphosphate (ATP), which muscle cells turn into mechanical energy.

Humans and other vertebrates have three types of muscle: skeletal, smooth, and cardiac.

Skeletal muscles move the external parts of the body and the limbs. They cover the bones and give the body its shape.

As skeletal muscles only pull in one direction, they work in pairs. When one muscle in the pair contracts, the other expands, and this facilitates movement.

The muscles attach to strong tendons, which either attach to or directly connect with the bones. The tendons extend over the joints, and this helps keep the joints stable. A person in good health can consciously control their skeletal muscles.

Most visible body movements — such as running, walking, talking, and moving the eyes, head, limbs, or digits — occur when the skeletal muscles contract.

Skeletal muscles also control all facial expressions, including smiles, frowns, and mouth and tongue movements.

Skeletal muscles are continually making tiny adjustments to maintain the body’s posture. They keep a person’s back straight or hold their head in one position. Together with the tendons, they keep the bones in the right position so that the joints do not dislocate.

Skeletal muscles also generate heat when they contract and release, and this helps maintain body temperature. Nearly 85%Trusted Source of the heat that the body produces comes from muscle contraction.

These are dense and rich in myoglobin and mitochondria. They have capillaries, which give them their red color. This type of muscle can contract for a long time without much effort. Type I muscles can sustain aerobic activity using carbohydrates and fats as fuel.

These muscles can contract rapidly and with a lot of force. The contraction is strong but short-lived. This type of muscle is responsible for most of the body’s muscle strength and its increase in mass after periods of weight training. Compared with slow-twitch muscle, it is less dense in myoglobin and mitochondria.

Skeletal muscles are striated, which means that they consist of thousands of equally sized sarcomeres, or muscle units, which have transverse bands. A striated muscle appears striped under a microscope because of these bands.

When the bands in the sarcomeres relax or contract, the whole muscle extends or relaxes.

Different bands within each muscle interact, allowing the muscle to move powerfully and smoothly.

Medical News Today