Transcript
Considered as Seat of soul by Rene
Descartes in 17th century
Third eye
Secretes melatonin
Helps in functioning of biological clock
Helps maintaining circadian rhythm
Role in reproduction
Aka – epiphysis
5 * 7 mm -150 mg
Situated between superior colliculi in
diencephalon
Forms posterior boundary of third ventricle
under corpus callosum
Above the hypothalamus
Cells – 2 types
stromal cells – secretary
glial cells
Gland contains highly permeable capillaries
Size – infants >adults
Calcification – importance
N-acetyl -5 methoxy tryptamine
Precussor – tryptophan
Plasma Levels Higher in night
Higher in children than adults
1-3 yrs -- 250pg/ml
8-15yrs – 120 pg
20-27 yrs – 70pg
67-84 yrs – 30pg
Metabolized in the liver by 6 hydroxylation and conjugation
ML-1 high affinity with two sub types mel 1a
,1b
ML -2 low affinity
Both are G protein coupled receptor
Shows diurnal variation
Secreted more during dark period of the day
Correlates to various internal activities
Role of hypothalamus in circadian rhythm
Role in circadian rhythm
Effects on gonads
Effects on MSH and ACTH
Induction of sleep
Inhibition of puberty
Lymphoid structure of lower neck in front of
trachea below thyroid
10-12g at birth and gradually enlarges till
puberty to reach 20 -30g
reduces in size with age 3-6g
Castration – effects on thymus
Cortex – actively multiplying lymphocytes
Medulla – reticular epithelial cells and some
lymphocytes in Hassall's corpuscles
Immunological ; maturation of T lymphocytes
Thymosin ; reticulo epithelial cells , lymphopoiesis
in the period of 3months before and 3 months after birth
Thymectomy and its effects
1) lymphopenia and lymphoid atrophy
2) failure to produce Ab
3) reduced delayed hypersensitivity
4)failure to produce graft rejection
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