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Pineal Gland (Epiphysis Cerebri) (Introduction (Pine cone shaped gland,…
Pineal Gland
(Epiphysis Cerebri)
Introduction
Pine cone shaped gland
Conical, grey body
Length: 5-8mm Width:3-5mm
Diencephalon of the brain
Regulation of endocrine functions
changes in the levels of progesterone, estradiol, luteinizing hormone and thyroid levels.
Secretion of Hormone Melatonin
communicates information about environmental lighting to various parts of the body
Entrain biological rhythms and has important effects on reproductive function of many animals
Light exposure (Retina) > Suprachiasmatic nucleus (hypothalamus) > Spinal Cord > Superior Cervical Ganglia (post-ganglionic neurons) > Pineal Gland
Conversion of nerves signals to endocrine signals
Nerves Signals (sympathetic system of peripheral nervous system) > hormone
Hormone
Melatonin
Sleep-wake cycle
Melatonin (Daylight: low; Night : high)
Reaction over photoperiod
Decrease motor activity
Induce fatigue
Lower body temperature
Entrain sleep-wake cycles
Influence Sexual Development
Melatonin block secretion of gonadotropins (LH and FSH)
pineal gland measure daylength and adjust secretion of melatonin
Seasonal changes in daylength have profound effects on reproduction in many species
