Downloaded 34 times
More Related Content
Thyroid
- 1. THYROID GLAND By, Ramya V, 1stM.SC. ZOOLOGY, BHARATHIAR UNIVERSITY, COIMBATORE.
- 2.
- 3. SHAPE OF THYROID GLAND •Thyroid consist of two lobes connected by a narrow isthmus. • Each lobe is pyramidal in shape, with its apex directed upward and its base directed downward. • A butterfly-shaped organ. • A small pyramidal lobe projecting upward from the isthumus is often present to the left of the midline.
- 4. SIZE OF THYROIDGLAND • The thyroid gland weighs 10 to 20 gms in normal adults. • Thyroid volume measured by ultrasonography (US) is slightly greater in men than women. • It increases with age and body weight. • It decreases with increasing iodine intake. • The thyroid is one of the most vascular organs in the body.
- 5. LOCATION • The normalthyroid gland is immediately caudal to the larynx and the anterolateral portion of the trachea. • The thyroid is bordered by the trachea and esophagus medially and the carotid sheath laterally.
- 6. ANATOMY OF THYROID GLAND •The tissue of the thyroid gland is composed mostly of thyroid follicles. • The follicles are made up of a central cavity filled with a sticky fluid called colloid. • Surrounded by a wall of epithelial follicle cells. • Follicle consist of 2 types of cells, namely principle cells and parafollicullar cells or c- cells.
- 9. FUNCTIONS OF THYROID •Increase pulmonary ventilationand thecellular uptake and utilizationof oxygen. • Regulatethe functioning ofnervous system. • Promote theintestinalabsorption and also thesynthesis of glucose. • Maintainor improve milk production in lactating females.
- 10. • The hormonereduces cholestrol level. • Influence the rate at which food moves through the digestive tract. • Control the rate at which dying cells are replaced. • Promote » Growth, » Differentiation, » Development.
- 11. BIOSYNTHESIS OF TH •Thyroid hormone produces three types of hormones • They are » Thyroxine (T4) ortetraiodothyroxine, » Thyroxine (T3) or triiodothyroxine, » Calcitonin.
- 12. COMPARISION T4 • Major hormonesecreted by the thyroid follicles. • 4 bound iodine atoms. • Constructed from the linkage of 2 tyrosine amino acid. T3 • Most is formed at the target tissues by conversion of T4 to T3. • 3 bound iodine atoms. • Constructed from the linkage of 2 tyrosine amino acid.
- 13. CALCITONIN • Calcitonin secretedby thyroid gland. Associated hormones Chemical class Chemical class Thyroxine (T4), triiodothyronine (T3) Amine Stimulate basal metabolic rate. Calcitonin Peptide Reduces blood Ca2+ levels.
- 14.
- 15. BIOSYNTHESIS • Active uptakeof iodide into follicular cell. • Iodide iodine - H2O 2 (catalysed by TPO). • Active uptake of iodine at follicular/ colloid interface. • Incorporation of iodine onto tyrosine residues of thyroglobulin. • Coupling of iodinated tyrosine. • Storage of T3 and T4.
- 16. PROCESS 1. Iodine formation, 2.Thyroglobulin formation, 3. Iodination, 4. Coupling, 5. Sceretion of thyroid hormone.
- 18. 1. Iodine formation •Iodine- raw material • Iodine actively transported into the follicle cells by the action of sodium- iodide symporter. • One iodide ion along with 2 Na ions across plasma membrane. • Energy gets from Na- K pump. • Process of concentrating iodide in the cell- iodide trapping. • Iodide secreted into the colloid.
- 19. 2.Thyroglobulin formation • Itis a glycoprotein – 2 sub units. • Synthesized in thyroid cells. • Following the entry of amino acids from extra cellular fluid. • Secreted into colloid – exocytosis. • Granules contains thyroid peroxidase.
- 20. 3. Iodination • Iodinebinds with thyroglobulin – organification. • Thyrosine iodized to monoiodothyrosin and then to diiodothyrosine. • Iodinase-enzyme. • 1 Iodine + 1 Thyrosine = MIT • 2 Iodine+ 1 Thyrosine = DIT
- 21. 4. Coupling ofiodotyrosyls • 2 DIT = T4 • 1 MIT + 1 DIT = T3 • Drugs that inhibit oxidation also inhibits coupling • The thyroid hormones formed (T3/T4) remain as integral parts of thyroglobulin – Still attached to thyroglobulin, stored in lumen of follicles until degraded later
- 22. 5. Secretion ofthyroid hormone • Thyroxin bound to thyroglobulin into follicular cells. • TSH stimulates pinocytosis of thyroglobulin into follicular cell. • Lysozyme enzyme hydrolyze peptide bonds • Release T4 from thyroglobulin. • T3 & T4 discharge freely into capillaries.
- 23.
- 24. THYROID DISORDERS • Thyroidstorm • Goiter Hyperthyroidisim • Cretinism • Myxoema • Sick euthyroiditis • Subacute thyroiditis Hypothyroidisim
- 25. HYPERTHYROIDISIM • Hyperthyroidism isa condition in which an overactive thyroid gland is producing an excessive amount of thyroid hormones that circulate in the blood. • Thyroid hormones include thyroxine (T4) and triiodothyronine (T3), representing 99.9% and 0.1% of thyroid hormones, respectively. • T3 is actually the most active thyroid hormone. • Much of the T4 is converted to T3 in the bloodstream.
- 26. GOITER • A goiteris an enlarged thyroid gland that causes the neck to swell. • The degree of swelling and the severity of symptoms produced by the goiter depends on the individual. • Some cases involve a small amount of swelling, whereas others can involve considerable swelling that actually constricts the trachea and causes breathing problems.
- 27. causes of goiter •Nodules - benign lumps. • Smoking - thiocyanate in tobacco smoke interferes with iodine absorption. • Hormonal changes - pregnancy, puberty, and menopause can affect thyroid function. • Thyroiditis - inflammation caused by infection. • Lithium - a psychiatric drug that can interfere with thyroid function. • Overconsumption of iodine - too much iodine can cause a goiter. • Radiation therapy - particularly to the neck.
- 28. SYMPTOMS • A visibleswelling at the base of your neck that may be particularly obvious when you shave or put on makeup. • A tight feeling in your throat. • Coughing. • Hoarseness. • Difficulty swallowing . • Difficulty breathing.
- 29. HYPOTHYROIDISIM • Hypothyroidism, orunderactive thyroid, develops when the thyroid gland fails to produce or secrete as much thyroxine (T4) as the body needs. • Thyroid gland doesn't produce enough of certain important hormones. • Hypothyroidism upsets the normal balance of chemical reactions in body. • abnormally low activity of the thyroid gland, resulting in retardation of growth and mental development in children and adults.
- 30. IN CHILD INADULT HYPOTHYROIDISM CRETINISM MYXODEMA
- 31. CRETINISIM MYXOEDEMA Definition Itis a condition arising from a deficiency of thyroid hormone, which is characterized by dwarfism and mental retardation. It is a disease resulting from the under-activity of the thyroid gland, which is characterized by puffy eyes, face, hands and mental sluggishness. Cause It is caused due to low levels of iodine in the body. It is caused due to low levels of thyroid hormone in the blood. Symptoms Fatigue Lethargy Mental impairment Depression Cold intolerance Hoarseness Dry skin Weight gain Swelling of skin Hair loss Mental impairment Bone maturity delay Slow thoughts and reflexes. Thickened skin Protruding stomach Treatment An increase in an iodine filled diet helps preventing cretinism. It can be managed by treating the underlying cause of the disease. Hypothyroidism Neonatal hypothyroidism. Adult hypothyroidism
- 32.
- 33. PHARATHYROID GLAND • Parathyroidglands are small endocrine glands. • Humans usually have four parathyroid glands, variably located on the back of the thyroid gland. SIZE • Normal parathyroid glands are approximately the size of a grain of rice or a lentil. • Normal glands are usually about 5 by 4 by 2 mm in size and weight 35 to 50 milligrams.
- 35. HISTOLOGY Two unique typesof cells are present in the parathyroid gland • Chief cells, which synthesize and release parathyroid hormone. These cells are small, and appear dark when loaded with parathyroid hormone, and clear when the hormone has been secreted, or in their resting state. • Oxyphil cells, which are lighter in appearance and increase in number with age, have an unknown function.
- 36. PARATHYROID HORMONE (PTH) • Parathyroidhormone (PTH), also called parathormone or parathyrin. • It is secreted by parathyroid gland
- 37. FUNCTIONS • Increase bloodcalcium concentration when it gets too low. • Increase renal tubular reabsorption of calcium. • Mechanism of raising blood calcium • Stimulate osteoglast to release more calcium from bone. • Decreases secretions of calcium by kidney. • Activates vitamin-D, with stimulates the uptake of calcium from the intestine.
- 38. CALCITONIN • Calcitonin isa hormone secreted by the thyroid gland that reduces the concentration of blood calcium level when it has risen to an above normal level. • This polypeptide hormone is made up of 32 amino acids and is produced mainly by the parafollicular cells (also known as C cells) of the thyroid gland. • In fish, birds and other non-mammalian animals, calcitonin is produced by cells of the ultimobranchial body.
- 39. CALCIUM • the recommendeddaily intake • the plasma concentration • calcium excreted • 1000mg • 2.22.22.6mmol/L • Kidneys 2.5 10mmol/24 hrs - 2.5-
- 41.
Editor's Notes
- #10 i