Disorders of muscular system

Disorders of muscular system

• Myasthenia gravis — an autoimmune disorder in which antibodies block the acetylcholine receptors on the sarcolemma at the neuromuscular junction, disrupting the normal signal for contraction. This leads to progressive fatigue, weakness and eventual paralysis of skeletal muscles; as the disease advances it can make chewing, swallowing, talking and even breathing difficult.
• Tetany — rapid, involuntary muscle spasms caused by a deficiency of parathyroid hormone, which leads to abnormally reduced calcium levels in the blood (parathyroid hormone normally helps regulate blood calcium).
• Muscle fatigue — the inability of a muscle to keep contracting after repeated stimulation, caused by a shortage of ATP and the build-up of lactic acid from anaerobic glucose breakdown when oxygen supply cannot keep pace with demand.
• Atrophy — a decline in muscle size and strength caused by prolonged disuse (for example in chronic bedridden patients), where reduced muscular activity leads to a reduction in fibre size and overall weakness.
• Muscle pull — essentially a muscle tear: a traumatic overstretching of muscle fibres beyond their elastic limit produces a tear (sprain). A very common everyday example is back pain caused by muscle pull from prolonged static, poor-posture sitting.
• Muscular dystrophy — a group of genetic diseases marked by progressive degeneration of skeletal muscle fibres, causing steadily worsening weakness that can eventually prove fatal through lung or heart failure. The most common form is Duchenne Muscular Dystrophy (DMD). …