Q.Discuss, with their causes and main features, the following disorders of the muscular and skeletal systems: myasthenia gravis, tetany, muscular dystrophy, arthritis, osteoporosis and gout.

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Six named disorders affect the muscular and skeletal systems at different sites: myasthenia gravis (neuromuscular junction), tetany (low blood calcium), muscular dystrophy (muscle fibre), arthritis, osteoporosis and gout (joints/bone). …

The muscular and skeletal systems work together as a single locomotor system, so disorders affecting them can originate at several different sites, each with its own underlying cause. Myasthenia gravis is an autoimmune disorder in which the body produces antibodies against its own acetylcholine receptors at the neuromuscular junction; because acetylcholine released by the motor neuron can no longer act effectively on these receptors, transmission of the nerve signal to the muscle fibre is progressively impaired, causing muscle fatigue and weakness that worsens with repeated use, and in severe cases can progress to paralysis. Tetany is a condition of rapid, involuntary muscle spasms (twitches), and its immediate cause is a fall in the level of calcium in the blood and other body fluids below the normal range, since calcium is essential for the controlled functioning of nerve and muscle tissue. Muscular dystrophy refers to a group of disorders, mostly genetic in origin (Duchenne muscular dystrophy being the best-known and most severe example), in which skeletal muscle fibres undergo progressive degeneration over time, being gradually damaged and replaced by connective and fatty tissue, causing steadily increasing muscle weakness. Arthritis is inflammation of one or more joints and can arise from more than one cause: rheumatoid arthritis is an autoimmune condition in which the immune system attacks the tissue lining the joints, osteoarthritis is the wear-and-tear degeneration of joint cartilage that becomes more common with age, and gouty arthritis results from the deposition of uric acid crystals within a joint; in every form, the affected joint becomes painful, swollen and stiff. Osteoporosis is an age-related disorder in which bone mass and density decrease over time, making bones progressively more porous, brittle and liable to fracture, and it is linked to the falling levels of oestrogen that follow menopause, which is why it is markedly more common and typically more severe in p …

Go through each of the six named disorders in turn, stating for each: the site affected, the underlying …

Treating all six disorders as variations of the same underlying problem simply because they all affect movement -- each has a genuinely distinct cause (autoimmune, mineral, genetic, infla …