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Locomotion and Movement - Disorders (Myasthenia gravis, Tetany, Muscular dystrophy, Arthritis, Osteoporosis, Gout)

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Myasthenia Gravis: An autoimmune disorder affecting the neuromuscular junction. It involves the production of antibodies that block or destroy acetylcholine (AChACh) receptors, leading to fatigue, weakening, and paralysis of skeletal muscles.

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Muscular Dystrophy: A progressive degeneration of skeletal muscle, which is primarily a genetic disorder (e.g., Duchenne muscular dystrophy).

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Tetany: Characterized by rapid spasms (wild contractions) in muscles due to low Ca2+Ca^{2+} levels in body fluids (hypocalcemia).

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Arthritis: A general term for the inflammation of one or more joints, causing pain and stiffness.

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Osteoporosis: An age-related disorder characterized by decreased bone mass and increased fragility, which leads to a higher risk of fractures. A common cause is the decreased level of estrogen in post-menopausal women.

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Gout: Inflammation of joints caused by the accumulation of uric acid (C5H4N4O3C_5H_4N_4O_3) crystals in the joint cavities.

📐Formulae

↓[Ca2+]extracellular  ⟹  Tetany\downarrow [Ca^{2+}]_{\text{extracellular}} \implies \text{Tetany}

↓Estrogen∝1Risk of Osteoporosis\downarrow \text{Estrogen} \propto \frac{1}{\text{Risk of Osteoporosis}}

Uric Acid Accumulation→Gouty Arthritis\text{Uric Acid Accumulation} \rightarrow \text{Gouty Arthritis}

💡Examples

Problem 1:

A 65-year-old female patient presents with frequent fractures and a significant decrease in bone mineral density. Blood tests show a decline in estrogen levels. Identify the disorder.

Solution:

Osteoporosis

Explanation:

Osteoporosis is an age-related disorder common in post-menopausal women due to reduced estrogen levels, which leads to decreased bone mass and increased susceptibility to fractures.

Problem 2:

During a clinical examination, a patient exhibits wild, involuntary muscle contractions. Lab results indicate a deficiency in serum Ca2+Ca^{2+}. What is the likely diagnosis?

Solution:

Tetany

Explanation:

Low levels of calcium ions (Ca2+Ca^{2+}) in the body fluid increase neuronal excitability, causing rapid muscle spasms known as Tetany.

Problem 3:

Distinguish between Myasthenia gravis and Muscular dystrophy based on their causative factors.

Solution:

Myasthenia gravis is an autoimmune disorder; Muscular dystrophy is a genetic disorder.

Explanation:

Myasthenia gravis is caused by the immune system attacking AChACh receptors at the neuromuscular junction, whereas Muscular dystrophy involves a genetic mutation (often in the dystrophin gene) leading to muscle fiber degeneration.

Disorders (Myasthenia gravis, Tetany, Muscular dystrophy, Arthritis, Osteoporosis, Gout) Revision…