Muscular system
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The body’s engine for movement and strength
The muscular system is the body’s network of muscles that allows movement, strength, and control. Every time you walk, smile, or even blink, your muscles are working. Muscles are made of special fibers that can tighten and relax. When they contract, they pull on [[Bone|bones]] and create motion. The body has over 600 muscles, making up about half of its weight.
Muscles are not all the same. There are three main types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are attached to bones and help you make voluntary movements, such as running or lifting. Smooth muscles are found in organs like the stomach and blood vessels. They work automatically to move food or control blood flow. The cardiac muscle is found only in the heart and keeps it beating rhythmically without stopping.
Skeletal muscles are controlled by the nervous system. When your brain sends a signal through the nerves, the muscle contracts. Muscles work in pairs—when one tightens, the other relaxes. For example, when you bend your arm, the biceps muscle contracts while the triceps relaxes. This teamwork makes movement smooth and precise.
Muscles need energy to work, which comes from the food you eat. oxygen from the blood helps turn nutrients into energy inside muscle cells. That’s why the muscular system is closely connected with the circulatory system and the respiratory system. During exercise, your heart beats faster to supply muscles with more oxygen and energy.
Besides movement, muscles also help with posture, stability, and body temperature. Even when you sit still, muscles in your back and neck keep you upright. When it’s cold, muscles produce heat by shivering. Strong and flexible muscles protect your joints and make daily activities easier.
To keep muscles healthy, it’s important to stay active, stretch, and eat foods rich in protein and minerals. Rest is also vital because muscles grow and repair during sleep. The muscular system is not only about strength—it’s about coordination, balance, and the energy that powers life’s every motion.
Muscles are not all the same. There are three main types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are attached to bones and help you make voluntary movements, such as running or lifting. Smooth muscles are found in organs like the stomach and blood vessels. They work automatically to move food or control blood flow. The cardiac muscle is found only in the heart and keeps it beating rhythmically without stopping.
Skeletal muscles are controlled by the nervous system. When your brain sends a signal through the nerves, the muscle contracts. Muscles work in pairs—when one tightens, the other relaxes. For example, when you bend your arm, the biceps muscle contracts while the triceps relaxes. This teamwork makes movement smooth and precise.
Muscles need energy to work, which comes from the food you eat. oxygen from the blood helps turn nutrients into energy inside muscle cells. That’s why the muscular system is closely connected with the circulatory system and the respiratory system. During exercise, your heart beats faster to supply muscles with more oxygen and energy.
Besides movement, muscles also help with posture, stability, and body temperature. Even when you sit still, muscles in your back and neck keep you upright. When it’s cold, muscles produce heat by shivering. Strong and flexible muscles protect your joints and make daily activities easier.
To keep muscles healthy, it’s important to stay active, stretch, and eat foods rich in protein and minerals. Rest is also vital because muscles grow and repair during sleep. The muscular system is not only about strength—it’s about coordination, balance, and the energy that powers life’s every motion.
What We Can Learn
- The muscular system controls all body movement.
- There are three types of muscles: skeletal, smooth, and cardiac.
- Muscles work with bones and nerves to create motion.
- Exercise, good food, and rest keep muscles strong and healthy.
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