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As blood calcium climbs in hyperparathyroidism, how do membrane permeability to sodium and nervous responsiveness change?

APermeability falls and responsiveness is reduced
BPermeability rises and responsiveness is reduced
CPermeability falls and responsiveness increases
DPermeability rises and responsiveness increases
Answer & Solution
Correct answer: A. Permeability falls and responsiveness is reduced
1. Hyperparathyroidism is overproduction of parathyroid hormone, so calcium is pulled out of bone. 2. Excessive calcium reabsorption from bone lowers bone density and invites fractures or deformity. 3. As blood calcium rises, cell membrane permeability to sodium falls. 4. Reduced sodium permeability makes the nervous system less responsive. 5. Calcium may also deposit in tissues and organs and impair how they work. 6. The opposite pairing, rising permeability with twitching and spasms, belongs to hypoparathyroidism and its low blood calcium. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 17 "The Endocrine System", section 17.5 The Parathyroid Glands_
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