(2). Steroid-SERsecreting cells:EM:SER,lipid dropletsMit with tubular-vesicularcristae.Secretion:Steroids
(2). Steroid - secreting cells: EM: SER, lipid droplets Mit with tubular 6 -vesicular cristae. Secretion: Steroids
2. ThyroidA.General structure:Capsule +Parenchyma ( thyroid follicles + c.t.)1Parafollicula7Follicular cellscells8Paraflicularcells2Follicle withcolloidg InterlobularLar3Follicular cellsconnectivetissue10Venule4Follicle11 Interfollicular(tangentialconnectivesection)fissue12 Follicle with5ConnectiveRight lobeLettlobsretracted colloidtissue sepla6Arteriole13Capillaries
2. Thyroid A. General structure: Capsule +Parenchyma ( thyroid follicles + c. t .) 7
B. Thyroid follicles:LM:(1) simple epitheliumFolliclessquamous(hypoactive)Colloidcuboidalorcolumnar(hyperactive)(2)ColloidAcidophiliclodatedthyroglobulin.EM:RER,Golgi.,secretorygranules,Ly(iodidepump,receptorsforTSH)Function: synthesize and secretetriiodothyronine(T3)&thyroxine(T4)
B. Thyroid follicles： LM: (1) simple epithelium. squamous (hypoactive) cuboidal or columnar (hyperactive) (2) Colloid 8 Acidophilic Iodated thyroglobulin. EM: RER, Golgi., secretory granules, Ly ( iodide pump, receptors for TSH ). Function: synthesize and secrete triiodothyronine (T3) & thyroxine(T4)
Synthesis of triodothyronine (T3)&thyroxine(T4):A.synthesisof thyroglobulinlodinatedthyroglobulinincolloidRERGolgi.AA-thyroglobulinColloidvesicleglycosylatedthyroglobulinApicalvesiclelodidecontainingoxidationcolloid.thyroglobulinB.iodinationofthyroglobulinperoxidasepumpMannoselodide→iodide→activatediodideincorporation(blood)(cytosol)(colloid)Thyroglobulinperoxidasesynthesistyrosine residuesofThyroglobulin(colloid)lodideAminoacids9iodated thyroglobulin
Synthesis of triiodothyronine (T3) & thyroxine(T4): A. synthesis of thyroglobulin AA thyroglobulin glycosylated thyroglobulin colloid. B. iodination of thyroglobulin RER Golgi. vesicle 9 B. iodination of thyroglobulin Iodide iodide activated iodide (blood) (cytosol) (colloid) tyrosine residues of Thyroglobulin (colloid) iodated thyroglobulin. pump peroxidase peroxidase
Release of thyroid hormones (T3& T4)UptakeofcolloidTSHbyendocytosisLysosomesiodatedthyroglobulinumLysosomeand(colloid)colloiddropletfuseendocytosisiodatedthyroglobulinDigestionby(colloid droplet)enzymesreleasesthyroidhormonesLY(T3, T4)T3,T4T3,T4bloodFunctionofT3&T4:LysosomalThyroid stimulatinghormoneboundenzymeCretinsm:synthesistoreceptor
Release of thyroid hormones (T3 & T4) iodated thyroglobulin (colloid) TSH iodated thyroglobulin (colloid droplet) endocytosis 10 Ly T3,T4 blood Function of T3 & T4: Cretinsm: