CBSE Class 10 Answered

Pineal gland produces melatonin hormone. This hormone is important to maintain the sleep patterns and maintain the photoperiodic functions. Pineal gland appears to play a major role in sexual development, hibernation in animals, metabolism, and seasonal breeding.

Melatonin levels are high at night and low during the day. With dawn the pineal gland stops producing melatonin, and wakefulness and alertness ensue. The high level of melatonin production in young children may explain their tendency to sleep longer than adults.

Melatonin has important effects in integrating photoperiod and affecting circadian rhythms. Hence it has significant effects on reproduction, sleep-wake cycles and other phenomena showing circadian rhythm.

Melatonin levels are much higher in children under age seven than in adolescents and are lower still in adults. Melatonin apparently acts to keep a child's body from undergoing sexual maturation, since sex hormones such as luteotropin, which play a role in the development of sexual organs, emerge only after melatonin levels have declined.

Parathyroid gland secretes a hormone called parathormone or parathyroid hormone, that is important for calcium and phosphorus metabolism. It increases blood calcium levels. If calcium ion concentrations in extracellular fluid fall below normal, this hormone brings them back within the normal range. In conjunction with increasing calcium concentration, the concentration of phosphate ion in blood is reduced.

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