ZOO 3000 Lecture Notes - Lecture 20: Cytoplasm, Microvillus, Parenchyma

• School: University of Guelph
• Department: Zoology
• Course: ZOO 3000
• Professor: Fred Laberge

Document Summary

Pineal gland: pine cone-shaped structure located near center of brain in humans, 2 cell types, pinealocytes clumps, cords. Light via retina retinohypothalamic tract scn pvn scg pineal gland pathway: regulates melatonin secretion. Light inhibits melatonin secretion: melatonin secretion contributes to, circadian daily rhythms via regulation of clock gene activity in. Scn: seasonal synchronization of, reproduction via regulation of gnrh and prolactin secretion, coat growth, camouflage colouring. In anterior neck region, develops from pharyngeal endoderm: 2 lobes connected by isthmus. Thin connective tissue capsule with extensions into parenchyma that define lobes and lobules. Surround colloid (gel-like mass: 2 cell types, follicular cells. Towards the colloid: nucleus spherical and basal, cytoplasm basophilic in basal part, rest on basal lamina. Follicular cells have dual function of thyroglobulin synthesis and resorption: suppressing osteoclast activity. Inhibiting ca2+ absorption (gut) and reabsorption (kidney: thyroglobulin a iodinated glycoprotein component of colloid storage form of thyroid hormones, absorption/resorption stimulated by thyroid-stimulating hormone.