lec 8 thyroid.pptx

lec 8 thyroid.pptx - Thyroid Introduction to the thyroid...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Page 1 Introduction to the thyroid: anatomy, histology, hierarchy, feed-back regulation, effect of T3-T4 on Na/K ATPase and uncoupling proteins Biosynthesis of T3-T4: thyroglobulin, iodide pump, iodination and coupling reactions, lysosomes T3-T4 effects: metabolism, T°C/F control, growth / development, reproduction, tertiary hypometabolism (starvation, hibernation) mechanism of action: T4 to T3, T3 receptor, nuclear / mitochondrial sites, increase enzymes, Na/K ATPase, uncoupling proteins Pathology: goitrogens, hypo and hyperthyroidism, thyroid hormone resistance Thyroid 12 Introduction Thyroid & its “story lines”
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 2 Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction The human thyroid is located at the base of the neck wraped around the traquea S ± E Low power photomicrograph of a rat thyroid gland. The thyroid follicles shown in cross section are filled with uniformly staining colloid and are each composed of a single layer of epithelial cells (red arrow). Note that the follicles are not uniform in size or shape. The white arrow points to a parafollicular cell and the green arrow points to a connective tissue septum separating two lobules. Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction The thyroid is controlled by feedback systems that include the hypothalamus and the AP gland S ± E
Background image of page 2
Page 3 Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction The half - life of the thyroid hormones T3 and T4 is different Metabolism of T4 S ± E Rate of loss of serum radioactivity after injection of labeled thyroxine or triiodothyronine into human subjects. Metabolism of thyroxine. About 90% of thyroxine is metabolized by sequential deiodination catalyzed by deiodinases (types I, II, and III); the first step removes an iodine from either the phenolic or tyrosyl ring producing an active (T3) or an inactive (rT3) compound. Subsequent deiodinations continue until all the iodine is recovered from the thyronine nucleus. Green arrows designate deiodination of the phenolic ring and red arrows indicate deiodination of the tyrosyl ring. Less than 10% of thyroxine is metabolized by shortening the alanine side chain prior to deiodination. Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction TSH secretion is controlled by TRH, whose neuronal terminals are located in the ME TRH S ± E
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 4 Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction TSH secretion is controlled by TRH, whose cell bodies are located in the PVN TRH 3V 3V S ± E Thyroid gland Biosynthesis Effects Mechanism of action Pathologies Introduction TSH secretion is controlled mainly by a negative feedback of T3 - T4 T3 implanted unilateral in left PVN left PVN 3V right PVN TRH-mRNA S ± E
Background image of page 4
Page 5 Thyroid gland Biosynthesis
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/19/2011 for the course ENDOCRINOL 450 taught by Professor Advis during the Spring '11 term at Rutgers.

Page1 / 21

lec 8 thyroid.pptx - Thyroid Introduction to the thyroid...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online