There are about 600 muscles in the human body. Muscles have a range of functions from pumping blood and supporting the movement to lifting heavy weights or giving birth. Muscles work by either contracting or relaxing to cause movement. This movement may be voluntary (meaning the movement is made consciously) or done without our conscious awareness (involuntary).
Glucose from carbohydrates in our diet fuels our muscles. To work properly, muscle tissue also needs particular minerals, electrolytes and other dietary substances such as calcium, magnesium, potassium and sodium.
Make-up of muscle
Skeletal, smooth and cardiac muscle have very different functions, but they share the same basic composition. A muscle is made up of thousands of elastic fibres bundled tightly together. Each bundle is wrapped in a thin transparent membrane called a perimysium. An individual muscle fibre is made up of blocks of proteins called myofibrils, which contain a specialised protein (myoglobin) and molecules to provide the oxygen and energy required for muscle contraction. Each myofibril contains filaments that fold together when given the signal to contract. This shortens the length of the muscle fibre which, in turn, shortens the entire muscle if enough fibres are stimulated at the same time.
Different types of muscle
The three main types of muscle include:
Skeletal muscle
Skeletal muscles are attached to your bones through tendons. Each muscle is comprised of thousands of muscle fibres that are bundled together. The organized arrangement of these fibres leads to a striped pattern. Because of this, you may also hear skeletal muscle referred to as striated muscle. Skeletal muscle is predominantly involved in the movement. When one of these muscles contracts, it allows movement of a specific area of the body. Your skeletal muscles are voluntary. That means that you can control their movement. They’re the only category of muscle for which you can do this
Smooth muscle
Smooth muscle is arranged in layered sheets that contract in waves along the length of the structure. Another common term is an involuntary muscle since the motion of smooth muscle happens without our conscious awareness. Smooth muscle is found in the walls of hollow organs such as the Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal organs, for example, moving food along the Oesophagus
Cardiac muscle
Found only in the walls of the heart. Similar to skeletal muscles in that it is striated and multinucleated, and with smooth muscles in that its contractions are not under controlled by the autonomic nervous system. However, even without a nervous input contraction can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing continuous aerobic metabolism.
FUNCTIONS OF MUSCULAR SYSTEM
Skeletal muscles are responsible for the movements
Cardiac and smooth muscles help your heartbeat and blood flow through your body
Respiration
Smooth muscles contract and relax as food passes through your body during digestion. These muscles also help push food out of your body through defecation, or vomiting when you’re sick.
Smooth and skeletal muscles in the urinary system work together so you can urinate
Smooth muscles of the uterus contract and relax to help push the baby through the vagina.
your eye sockets are made up of six skeletal muscles that help you move your eyes. And the internal muscles of your eyes are made up of smooth muscles. All these muscles work together to help you see
Skeletal muscles in your core help protect your spine and help with stability
Skeletal muscles also control posture
Muscle disorders
Muscle disorders may cause weakness, pain, loss of movement and even paralysis. The range of problems that affect muscles is collectively known as myopathy. Common muscle problems include:
Injury or overuse, including sprains or strains, cramps, tendonitis and bruising
Genetic problems, such as muscular dystrophy
Inflammation, such as myositis
Diseases of nerves that affect muscles, such as multiple sclerosis
Conditions that cause muscle weakness, such as metabolic, endocrine or toxic disorders; for example, thyroid, and adrenal diseases, alcoholism, pesticide poisoning, medications (steroids, statins) and myasthenia gravis
Cancers, such as soft tissue sarcoma.
Physiotherapists treat a wide range of muscular conditions including muscle strains, tear, atrophy through muscle rehabilitation, sports enhancement of muscle, physical exercise promotion and education etc...
Devni Munasinghe
References
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