17.7 The Pineal Gland

Pineal Gland Location

The pineal gland is located inferior and somewhat posterior to the thalamus.

Pineal Gland Structure

The pineal gland is a tiny endocrine gland made up of pinealocyte cells.

Function of Melatonin

Melatonin regulates sleep-wake cycles and circadian rhythms.

Melatonin Production

Melatonin is produced by pinealocyte cells in the pineal gland, derived from serotonin.

Light Influence on Melatonin

Melatonin secretion decreases in response to light and increases in darkness.

Suprachiasmatic Nucleus (SCN)

The SCN is a region in the hypothalamus important for regulating biological rhythms.

Effect of Light on SCN

Light stimulates the retinas, sending impulses to the SCN that inhibit melatonin production.

Cyclical Pattern of Melatonin

Melatonin secretion follows a cyclical pattern correlating with light and dark exposure.

Circadian Rhythms

Circadian rhythms are the body's natural processes that follow a roughly 24-hour cycle.

Influences of Melatonin

Melatonin influences sleepiness, wakefulness, appetite, and body temperature.

Melatonin Levels in Children

Children have higher levels of melatonin than adults, which may inhibit puberty.

Antioxidant Role of Melatonin

Current research investigates melatonin's role as an antioxidant.

Effects of Jet Lag

Jet lag causes sleepiness during the day or wakefulness at night due to melatonin synthesis disruption.

Adjustment Duration for Jet Lag

It can take several days for melatonin synthesis to adjust to a new light-dark pattern.

Melatonin Supplements Use

Travelers may take melatonin supplements to help induce sleep.

Pinealocyte Cells

Pinealocyte cells are responsible for the production and secretion of melatonin.

Melatonin and Gonadotropins

Higher melatonin levels in children may prevent the release of gonadotropins, inhibiting puberty.

Melatonin and Biological Rhythms

Melatonin secretion plays a crucial role in maintaining circadian rhythms.

Light-Dark Cycle Regulation

Melatonin regulates the light-dark cycle that affects various physiological processes.