Question

Melatonin is secreted by:

• A. Thyrotrophs
• B. Gonadotrophs
• C. Pineal gland
• D. Adrenal gland

Hint:

The pineal gland is the primary source of melatonin, a hormone crucial for regulating the circadian rhythm. Its secretion increases in response to darkness.

Answer 1

The Correct Option is C

Step 1: Understanding melatonin secretion. Melatonin is a hormone primarily secreted by the pineal gland, a small endocrine gland located in the brain. 

Step 2: Role of melatonin. Melatonin regulates the sleep-wake cycle (circadian rhythm) and is influenced by the light-dark cycle. Its secretion increases in darkness and decreases in light. 

Step 3: Why other options are incorrect. 
- (A) Thyrotrophs: These are cells in the anterior pituitary gland that secrete thyroid-stimulating hormone (TSH), not melatonin. 
- (B) Gonadotrophs: These are pituitary cells that secrete gonadotropins like LH and FSH. 
- (D) Adrenal gland: Secretes hormones like cortisol, aldosterone, and adrenaline, but not melatonin.