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Questions
Describe the T. S. of thyroid gland
Sketch and label T.S. of the thyroid gland.
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Solution
Thyroid gland is externally covered by connective tissue sheath or capsule.
From the capsule, number of septa called trabeculae arise, which divide the thyroid gland into
several lobules. The lobules contain about 3 million thyroid follicles. Each thyroid follicle is oval in shape and varies in size. Larger follicles are present towards periphery, whereas smaller ones are present in the interior. The follicles are surrounded by a connective tissue called interfollicular tissue which contains blood vessels and nerve fibres.Each follicle is lined by a single layer of cuboidal glandular epithelium which rest on a very thin
basement. The follicular cavity or acinus is filled by dense amorphous semisolid substance called colloid, which is thyroglobulin, a precursor of thyroid hormone, thyroxine. Other cells bigger than follicular cells are also present singly or in groups in the connective tissue.
These are called parafollicular or ‘C’ cells.
They secrete hormone thyrocalcitonin.
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Column ‘II’ is a list of items related to ideas in Column ‘I’. Match the term in Column ‘II’ with a suitable idea given in Column ‘I’.
| Column A | Column B |
| (i) Pituitary | (a) produces male sex characteristics |
| (ii) Ovaries | (b) decreases blood sugar level |
| (iii) Thyroid | (c) increases heart and breathing rate raises blood pressure |
| (iv) Thymus | (d) produces female sex characteristics |
| (v) Adrenals | (e) is known as emergency hormone |
| (vi) Hypothalamus | (f) regulates the level of calcium and phosphorus |
| (vii) Pancreas | (g) increases the rate of metabolism |
| (viii) Testes | (h) maintains the level of calcium |
| (ix) Parathyroid | regulates the amount of water excreted in the urine. |
| (x) Cretinism | (j) simulates skeletal growth |
| (xi) Diabetes mellitus | (k) regulates the activities of other glands |
| (xii) Insulin shock | (l) stimulates the development of male and female sex organs |
| (xiii) Gigantism | (m) Shortage of glucose in the blood. |
| (xiv) Enlargement of breasts in adult males | (n) Over-secretion of growth hormone |
| (xv) Exophthalmic goiter | (o) Excess of glucose in the blood |
| (xvi) Acromegaly | (p) Over-secretion of thyroxin |
| (xvii) Addison’s disease | (q) Dwarfism and mental retardation |
| (xviii)Cretinism | (r) Over-secretion of cortical hormones |
| (xix) Dwarfism | (s) Under-secretion of the adrenal cortex |
| (xx) Adrenalin | (t) Under-secretion of thyroxin in children |
| (xxi) Vasopressin | (u) Over-secretion of growth hormones in adults |
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