Thyroid Hormones and Metabolic Rate

Thyroid Hormones and Metabolic Rate. THYROID HORMONES HELP REGULATE our BODY's METABOLISM TRIIODOTHYRONINE HO TYROSINE - BASED THYROXINE (Tg TETRAIODOTHYRONINE) FOLLICLES THYROID GLAND FOLLICULAR CELLS ( THYROCYTES J.

Synthesis and Secretion of thyroid metabolic hormone..

Weighs 15-20 gram in adults.. Secretes Thyroxine T4 and Triiothyrnine T3 that increase metabolic rate of the body..

Synthesis and Secretion of Thyroid Hormone.

Thyroxine 93%. Triiodothyronine 7%. Metabolically active hormone from thyroid gland..

Physiologic Anatomy of the Thyroid Gland. epithelial cens Red cens 76-10 Microscopic of the thyroid gland. stowing secretim of thyrqbbJl•n Into the fdbcles..

Physiologic Anatomy of Thyroid Gland. Follicles, filled with a secretory substance called colloid and lined with a cuboidal epithelial cells that secrete into the interior of the follicle..

Iodine. The required ingested iodine is 50 milligram each year (1mg/week)..

Iodine Trapping. Transported from the blood through the basal memebrane of the thyroid cell by the iodine pump, this is called iodine trapping..

Iodine Trapping and T3 ,T4 Synthesis. ER MIT. 4 Proteaæs H202 hetrmtfise MIT DIT 76-2 Thyroid celh.jz rno:har.sms transmrt. thyronr.é ed tnooonyrontne tumaton, and my. rox.ne ard troodothvonjre release into the bkx:d MIT. nonconyrosr•, OIT Scootyrosane, Ts tn. T.. thyroxre, L. thytc#buln.

Synthesis of T3,T4. The E.R and G.A synthesize and secrete into follicles a large glycoprotein molecule called Thyroglobulin..

Thyroglobultn (TG) H 202 eroxidase + Iodinatm e -...+O -........................................................+TG and Peroxidase coupling ER Golgi MIT. DIT T Secretion 4 proteases Colloid droplet MIT DIT Pinocytosis.

Converstion of iodide ion into an oxidize form of iodine..

12 76-a Chemistry ot c:Hz— — COOH tm•-tation..

After synthesis. Each thyroglobuline molecule contains upto 30 thyroxine and a few triiodothyronine in follicle..

T4, T3 are first cleaved from the thyroglobuline molecule, then release as free hormone.

Pinocytic vesicles that enter the thyroid cell. Then lysosomes in cell cytoplasm fuse with these vesicle to form digestuve vesicles..

Proteases digest the thyroglobulin molecule and triiodothyronine..

These then diffuse through the base of thyroid cell into the surrounding capillaries. Thus, thyroid hormone released into blood..

Monoiodothyronine and diiodothyronine during digestion are freed from the thyroglobuline but are not sectreted into blood..

Daily Rate of Sectretion of Thyroxine and Triiodothyronine.

+10 Thyroxine injected 10 Days Figure 76-4 Approximate prolonged effect on the basal metabolic rate caused by administering a Single large dose of thyroxine..

Anterior pitu•• ack t alamu Thy ( Thy • oid-stimulating hormone (TSH) T röid Ian Thyroid hormones (T3 and T4) Increased metabolism Growth and developme t ncreased catecholamine ffect.

Stimulation of carbohydrate metabolism.. Stimulation of fat metabolism..

8. Increased respiration.. 9. Increased GI motility..

Disorders Of Thyroid Hormones..

Hyperthyroidism Hypothyroidism Cretinism.

Hyperthyroidism.

Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine..

Symptoms. Unintentional weight loss, even when your appetite and food intake stay the same or increase Rapid heartbeat (tachycardia) — commonly more than 100 beats a minute Irregular heartbeat (arrhythmia) Pounding of your heart (palpitations) Increased appetite Nervousness, anxiety and irritability Tremor — usually a fine trembling in your hands and fingers Sweating Changes in menstrual patterns Increased sensitivity to heat Changes in bowel patterns, especially more frequent bowel movements An enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck Fatigue, muscle weakness Difficulty sleeping Skin thinning Fine, brittle hair.

Hypothyroidism.

Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn't produce enough of certain crucial hormones..

Symptoms. top-29.

Disorder of Hypothyroidism the thyroid gland Hyperthyroidism Cold intolerance Dry hair Puffy face Goiter Slow heartbeat Weight gain Constipation Hair loss Bulging eyes Goiter Rapid heartbeat Weight loss Diarrhea Heat intolerance Possible infertility and an increased risk of miscarriage. Irregular menstrual cycles Menstrual periods may ocx;ur less often, or with longer cycles.