21.18:
The Pineal Gland
The pineal gland is a small endocrine gland named for its pinecone shape. This gland is located on the roof of the third ventricle within the forebrain’s diencephalon region.
It is made of secretory cells called pinealocytes arranged in compact cords and clusters surrounding dense particles of calcium salts.
The pineal gland secretes the hormone melatonin, an amine derivative of serotonin.
The melatonin concentration in the blood is linked to light exposure and follows the day-night pattern. The secretion peaks at night when the photoreceptors in the eye do not detect light, leading to drowsiness.
In addition to regulating sleep, melatonin has antioxidant effects and mediates mating behavior by altering the timing and duration of the reproductive cycle, puberty, and sexual maturation.
21.18:
The Pineal Gland
The pineal gland, a diminutive endocrine structure named for its pinecone-shaped appearance, is situated atop the third ventricle within the diencephalon region of the forebrain. This gland, composed of secretory cells known as pinealocytes arranged in compact cords and clusters around dense particles of calcium salts, plays a pivotal role in hormonal regulation.
The primary secretion of the pineal gland is the hormone melatonin, derived from serotonin. The concentration of melatonin in the bloodstream exhibits a day-night pattern linked to light exposure. Notably, melatonin peaks at night when photoreceptors in the eye are devoid of light, inducing a sense of drowsiness.
Beyond its role in sleep regulation, melatonin exerts antioxidant effects, contributing to cellular protection. Additionally, this hormone significantly mediates mating behavior by influencing the timing and duration of the reproductive cycle, puberty, and sexual maturation. The intricate interplay between melatonin and various physiological processes underscores the multifaceted impact of the pineal gland on both circadian rhythms and reproductive functions.