The correct option is (a).
Explanation
The adrenal glands are paired endocrine structures located on the anterior part of each kidney. They are divided into two distinct tissues: the outer adrenal cortex and the inner adrenal medulla, both of which secrete hormones directly into the bloodstream to regulate various physiological processes.Statement 1 is Correct: The adrenal medulla secretes the hormone adrenaline (also known as epinephrine) and noradrenaline (norepinephrine). These are often referred to as "emergency hormones" or hormones of "fight or flight" because they are rapidly secreted in response to stress or danger, increasing alertness, heart rate, and glucose levels.
Statement 2 is Incorrect: The regulation of the 24-hour (diurnal) rhythm of the body, including the sleep-wake cycle, is the primary function of the pineal gland. The pineal gland secretes the hormone melatonin, which plays a central role in regulating circadian rhythms. The adrenal glands are not primarily responsible for this function.
Statement 3 is Incorrect: Adrenal glands are endocrine glands (ductless glands), meaning they release hormones directly into the blood. They do not secrete digestive enzymes. Digestive enzymes are secreted by exocrine glands, such as the gastric glands in the stomach lining and the acinar cells of the pancreas.
Key Takeaway: Adrenal glands are responsible for the stress response (via adrenaline) and metabolic regulation (via cortisol), while the pineal gland regulates the sleep-wake cycle (via melatonin).