Muscular System

The muscular system is mostly made up of muscles that allow your body to move and be flexible Other muscles move materials inside your body Muscle is the tissue that contracts and relaxes – this makes movement possible Muscle is made up of muscle cells

Three Types of Muscle

Your body has three kinds of muscle tissue: skeletal muscle, cardiac muscle and smooth muscle Each muscle type has a specific job in your body Because you are able to control the movement of skeletal muscles, these muscles are called voluntary muscles You are not able to control the movement of smooth muscles and cardiac muscles Muscles that are not under your control are called involuntary muscles

Smooth Muscle

Smooth muscle is found in internal organs and blood vessels It helps move materials through the body Arteries and veins contain a layer of smooth muscle that can contract and relax This controls blood flow through the blood vessel Smooth muscle movement in your digestive system helps move food through your intestines

Cardiac Muscle

Cardiac muscle is the tissue that makes up the heart Your heart never gets tired because cardiac muscle cells are able to contract and relax without ever getting tired In order to supply energy to all the cells, cardiac muscles have many mitochondria Contractions of the cardiac muscle push blood out of the heart and pump it around your body

Skeletal Muscle

Skeletal muscle is attached to your bones and allows you to move The tough strand of tissue that connects a muscle to a bone is a tendon When a muscle contracts, or shortens, the attached bones are pulled closer to each other Most skeletal muscles work in pairs around a joint One muscle in the pair, called the flexor, bends a joint The other muscle, the extensor, straightens the joint When one muscle of a pair contracts, the other muscle relaxes

Injuries and Disorders of the Muscular System

Some muscle diseases are hereditary Diseases that affect muscle function can also affect other body systems Muscular dystrophy is a hereditary disease that causes skeletal muscles to become weaker over time – it affects how muscle proteins form A strain is a muscle injury in which muscle is over stretched or torn Muscle tissue swells and can hurt Tendinitis can occur when tendons become inflamed or torn when muscles are overused

Benefits of Exercise

Exercise is any activity that helps improve physical fitness and health Benefits the muscular system, cardiovascular system and the skeletal system Exercises that raise your heart rate to a certain level for at least 60 minutes improve fitness of the heart Weight training helps bones stay dense and strong Resistance exercise helps improve muscle strength by building muscle power – involve short bursts of intense effort – lifting weights and pushups Endurance exercise allows muscles to contract for a longer time without getting tired – jogging and biking Flexibility refers to full range of motion of a joint