MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A patient presents with symptoms including muscle weakness, cramps, and irregular heart rhythms. Blood tests reveal abnormally low levels of calcium. Further investigation indicates a dysfunction in the regulation of serum calcium. Which endocrine gland is most likely impaired?
- AThyroid gland
- BPancreas
- CAdrenal gland
- DParathyroid gland
Show answer & explanationAnswer & explanation
Correct answer: D. Parathyroid gland
The parathyroid glands produce parathyroid hormone (PTH), which is the primary hormone responsible for increasing blood calcium levels by stimulating calcium release from bones, reabsorption in kidneys, and absorption in the gut. Low calcium levels indicate impaired parathyroid function.
Why the other options are wrong
- A. Thyroid gland produces thyroid hormones (metabolism) and calcitonin (lowers blood calcium).
- B. Pancreas produces insulin and glucagon, regulating blood glucose.
- C. Adrenal gland produces hormones like adrenaline and cortisol, involved in stress response and metabolism.
Parathyroid Gland Function
Small endocrine glands located in the neck, usually behind the thyroid gland, that produce parathyroid hormone (PTH), which plays a crucial role in regulating calcium and phosphate levels in the blood.
- Produces parathyroid hormone (PTH).
- PTH increases blood calcium levels.
- Achieves this by stimulating osteoclasts, kidney reabsorption, and vitamin D activation.
- PTH also decreases blood phosphate levels.
Memory trick: Parathyroid: PTH puts the calcium up high!