All questions of Chemical Coordination and Integration for NEET Exam

Thyroxine hormone increases BMR of body ...so option C

C . thyroxine increases the metabolic rate

Overview of Calcium and Phosphorus Regulation
Calcium and phosphorus are essential minerals involved in various physiological processes, including bone health, nerve function, and muscle contraction. The regulation of these minerals in the body is primarily controlled by hormones secreted by the parathyroid glands.
Parathyroid Hormone (PTH)
- The parathyroid glands, located behind the thyroid gland in the neck, secrete parathyroid hormone (PTH).
- PTH plays a crucial role in maintaining calcium homeostasis:
- It increases calcium levels in the blood by stimulating:
- The release of calcium from bones.
- The absorption of calcium in the intestines (via vitamin D).
- The reabsorption of calcium in the kidneys.
Calcitonin
- The thyroid gland also secretes calcitonin, which helps lower blood calcium levels. However, its role is less significant than that of PTH.
- Calcitonin works by:
- Inhibiting osteoclast activity (cells that break down bone).
- Promoting calcium deposition in bones.
Vitamin D
- Vitamin D, while not a hormone produced by the parathyroid glands, is essential for the action of PTH.
- It enhances intestinal absorption of calcium and phosphorus, contributing to overall mineral balance.
Conclusion
The parathyroid glands are vital for the regulation of calcium and phosphorus metabolism through the secretion of parathyroid hormone. This hormone works in concert with calcitonin and vitamin D to maintain the delicate balance of these minerals, essential for numerous bodily functions. Therefore, the correct answer is option 'D' - Parathyroid.

Thyrocalcitonin is a hypocalcemic hormone that is produced by thyroid gland...it decreases blood calcium level

Effects of Parathyroid Removal
Parathyroid glands are responsible for regulating calcium levels in the body. Removal of these glands can lead to various complications, one of which is tetany.

Tetany
Tetany is a condition characterized by involuntary muscle contractions and spasms. This occurs due to a decrease in calcium levels in the blood, known as hypocalcemia. The parathyroid glands play a crucial role in maintaining calcium balance by releasing parathyroid hormone (PTH), which helps in increasing calcium levels in the blood. Without the parathyroid glands, the body is unable to regulate calcium levels properly, leading to tetany.
In tetany, individuals may experience symptoms such as muscle cramps, twitching, numbness, tingling, and even seizures. These symptoms occur due to the overexcitability of nerves and muscles in the absence of adequate calcium levels.
Therefore, removal of the parathyroid glands can result in tetany due to hypocalcemia, highlighting the essential role these glands play in calcium homeostasis in the body.

The main function of thyroid gland is to maintain Basal metabolic rate. This is Ncert line. Refer NCERT, chapter endocrine gland

The primary organ responsible for regulating metabolism is the hypothalamus. An individual's basal metabolic rate is highly regulated by the thyroid gland through the secretion of thyroid hormone (TH). TH is used to refer to two similar molecules, thyroxin (T4) and triiodothyronine (T3). The thyroids secretion of TH is in turn regulated by the body's concentration of thyroid stimulating hormone (TSH) as part of a negative feedback loop with the hypothalamus...Thus, option B is right ans..

Option D

Overview of Thyroid-Related Conditions
Thyroid-related conditions are critical in understanding how thyroid hormones affect bodily functions. Let's analyze the options provided.
Option A: Thyroxine (T4) - Increases blood calcium levels
- Incorrect.
Thyroxine (T4) primarily regulates metabolism, not calcium levels. The hormone that increases blood calcium is parathyroid hormone (PTH).
Option B: Hypothyroidism - Causes exophthalmic goitre and weight loss
- Incorrect.
Hypothyroidism is characterized by weight gain, fatigue, and sometimes a goitre, but it does not cause exophthalmos (bulging eyes). Exophthalmos is typically associated with hyperthyroidism, particularly in Graves' disease.
Option C: Triiodothyronine (T3) - Regulates basal metabolic rate
- Correct.
Triiodothyronine (T3) is crucial for regulating the basal metabolic rate (BMR) and overall metabolism. It helps increase oxygen consumption and energy production in cells.
Option D: Graves’ Disease - Caused by iodine deficiency leading to goitre
- Incorrect.
Graves' disease is an autoimmune disorder that leads to hyperthyroidism and is not caused by iodine deficiency. Instead, iodine deficiency typically leads to hypothyroidism and goitre formation.
Conclusion
Based on the analysis, Option C correctly matches the thyroid-related condition with its associated feature. Triiodothyronine (T3) is essential for regulating the basal metabolic rate, making it the only accurate option among those presented. Therefore, the correct answer is Option C.

Goitre is actually a deficiency disorder caused due to the deficiency of iodine . It involves enlargement of thyroid gland. However , it can be also caused due to hyperthyroidism in some people.