Muscles

31 views01:26 min

Your body moves, stretches, and even pumps blood, all because of muscles. These tissues make up the muscular system, which includes all the muscles working together to keep you moving.

Each muscle is comprised of long cells called muscle fibers, which are packed with tiny units containing protein strands called actin and myosin.

When the brain sends a signal, these protein strands slide past one another, causing the muscle to shorten. This is called contraction.

After contraction, the muscle returns to its original shape, called relaxation.

Your body has different types of muscles. Some, like the ones that help you lift your arm, are under your control—these are called voluntary muscles. Others, like the muscles that control your heartbeat, work automatically. These are called involuntary muscles.

Based on their function and location, muscles are grouped into three types.

First, there are skeletal muscles that attach to bones and help with voluntary movements like jumping.

Next, there are smooth muscles, which are involuntary and found in organs like the stomach.

Lastly, cardiac muscle is also involuntary. It is found only in the heart and is responsible for pumping blood.

Overview

Loading...

$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Muscles

Muscles are tissues composed of fibers that contract to generate force and movement. They are essential for a wide range of bodily functions, including locomotion, posture maintenance, and internal processes such as circulation and digestion. Muscles operate in conjunction with the skeletal system, where tendons connect muscles to bones and exert force across joints. This interaction facilitates movements such as bending arms, walking, and smiling.

Science and Engineering Practices (SEP): Constructing Explanations and Designing Solutions

Researchers study how muscles contract, how they respond to exercise or fatigue, and how diseases like muscular dystrophy impair movement. This knowledge informs the development of medical treatments, fitness strategies, and rehabilitation protocols. You can explore the muscular system through hands-on investigations and creative problem-solving activities.

Activity Ideas:

Muscle Model Creation – Use elastic bands and craft materials to model how muscles contract and pull on bones to create movement.
Grip Strength Testing – Measure grip strength with a dynamometer or homemade device and compare results before and after exercise to observe fatigue effects.
Muscle Fatigue Timed Tests – Perform repeated motions (e.g., squats or push-ups) and record the time until fatigue to study endurance and recovery.
Muscle-Bone Interaction Simulation – Build a model arm with cardboard and string to simulate how muscles and tendons work together to move joints.

Crosscutting Concept (CCC): Structure and Function

Understanding how a muscle’s structure enables its function clarifies why different muscle types support distinct roles in the body.

Skeletal Muscle
Structure: Long, cylindrical fibers with striations due to the alignment of sarcomeres.
Function: Produces quick, forceful contractions that enable voluntary movements like lifting, walking, and speaking.
Smooth Muscle
Structure: Spindle-shaped, non-striated fibers arranged in sheets.
Function: Facilitates slow, sustained involuntary movements, such as food propulsion through the digestive tract or regulation of blood vessel diameter.
Cardiac Muscle
Structure: Branched, striated fibers with intercalated discs that synchronize contraction.
Function: Pumps blood efficiently and rhythmically throughout the body without fatigue.

Procedure

Transcript

Explore More Videos

Skeletal Muscle

Muscle Contraction

Muscle Structure

Muscle Function

Muscle Bone Interaction