Number of parathyroid glands in human: September 2005
**Question:** Number of parathyroid glands in human
**Core Concept:** Parathyroid glands are a group of four glands located in the neck, responsible for producing parathyroid hormone (PTH) which regulates calcium and phosphorus levels in the blood.
**Why the Correct Answer is Right:** The correct answer, **D**, states that there are four parathyroid glands in the human body. These glands are essential for maintaining calcium and phosphorus homeostasis in the blood. When calcium levels decrease, PTH is released by the parathyroid glands, stimulating the release of calcium from bones, increasing calcium absorption in the intestines, and decreasing calcium excretion in the kidneys. Conversely, when calcium levels rise, PTH inhibits these processes. This helps maintain a stable calcium and phosphorus balance in the blood.
**Why Each Wrong Option is Incorrect:**
A. **Two:** This option is incorrect because the parathyroid glands are a set of four glands. Each pair is adjacent to one of the four thyroid lobes, and they are located in the neck.
B. **Three:** This option is incorrect as well, as the human body has four parathyroid glands. Their presence is essential for calcium and phosphorus regulation.
C. **Five:** The parathyroid glands are not five, but four, and their role is crucial for maintaining normal calcium and phosphorus levels in the blood.
**Clinical Pearl:** Understanding the number and function of parathyroid glands is essential in diagnosing and managing disorders related to calcium and phosphorus levels, such as hyperparathyroidism and hypoparathyroidism.
**Correct Answer: D (Four)**
The correct answer, **D**, highlights the importance of the four parathyroid glands in maintaining calcium and phosphorus homeostasis. A thorough knowledge of the anatomy, physiology, and pathology related to these glands is crucial for medical students and practicing physicians, as it allows for accurate diagnosis and treatment of disorders associated with calcium and phosphorus levels, such as hyperparathyroidism and hypoparathyroidism.