Muscles

Muscles are a type of soft tissue in the human body that have the ability to contract and produce force, allowing for movement and maintaining posture. There are three main types of muscles in the body: skeletal, smooth, and cardiac.

Skeletal Muscles

Skeletal muscles are attached to the bones and are responsible for voluntary movements such as walking, running, and lifting objects. They are striated, meaning they have a striped appearance under a microscope, and are under conscious control.

Smooth Muscles

Smooth muscles are found in the walls of internal organs such as the stomach, intestines, and blood vessels. They are responsible for involuntary movements and are not under conscious control. Smooth muscles are non-striated, meaning they do not have a striped appearance under a microscope.

Cardiac Muscles

Cardiac muscles are found in the heart and are responsible for pumping blood throughout the body. Like skeletal muscles, cardiac muscles are striated, but they are involuntary, meaning they are not under conscious control.

Structure of Muscles

At the microscopic level, muscles are made up of long, cylindrical cells called muscle fibers. These muscle fibers contain myofibrils, which are the contractile units of the muscle. The functional unit of a muscle is the sarcomere, which is composed of actin and myosin filaments that slide past each other during muscle contraction.

Function of Muscles

The main function of muscles is to produce movement. They work in pairs, with one muscle contracting while the other relaxes to produce smooth and coordinated movements. Muscles also play a role in maintaining posture, stabilizing joints, generating heat, and aiding in the circulation of blood and lymph throughout the body.

Study Guide

1. What are the three main types of muscles in the human body?
2. Describe the structure of skeletal muscles.
3. What is the main function of muscles in the body?
4. Explain the role of sarcomeres in muscle contraction.
5. Give examples of voluntary and involuntary muscle movements.

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