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Question
Long answer question
Describe in brief an account of disorders of the thyroid.
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Solution
Disorders of the thyroid gland are caused due to hypersecretion and hyposecretion of thyroid hormones.
i. Hypersecretion of thyroid hormones: It is caused by an increase in the levels of thyroid hormones. This increases metabolic rate, sensitivity, sweating, flushing, rapid respiration, bulging of eyeballs, and affects various physiological activities.
Graves’ disease: Hyperthyroidism in adults results in this disorder. It is characterised by protruding eyeballs, increased BMR, and weight loss. Increased BMR produces a range of effects like increased heartbeat, increased B.P., higher body temperature, nervousness, irritability, and tremor of fingers.
ii. Hyposecretion of thyroid hormone: It is caused by a deficiency of thyroid hormones or removal of the thyroid gland (Thyroidectomy).
a. Cretinism: It is caused due to deficiency of thyroid hormones in infants. A cretin (individual suffering from cretinism) has reduced BMR and low oxidation. They are short-statured because the skeleton fails to grow. They are mentally retarded, show stunted growth and delayed puberty. They show dry skin, thick tongue, prolonged neonatal jaundice, lethargy and constipation. This can be treated by early administration of thyroid hormones.
b. Myxoedema: It is caused due to the deficiency of thyroid hormones in adults. It is characterised by a peculiar thickening and puffiness of skin and subcutaneous tissue particularly of the face and extremities. The patient lacks alertness, intelligence. The patient suffers from slow heart rate, low B.P., low body temperature (feels cold) and stunted sexual development.
c. Simple goitre: It is iodine deficiency goitre. Iodine is required for the synthesis of thyroid hormone and if there is a deficiency of iodine in the diet, it causes enlargement of the thyroid gland leading to simple goitre. This disease is common in hilly areas. Addition of iodine to table salt prevents this disease. The size of the thyroid gland is increased but the total output of thyroxine is decreased.
iii. Hyposecretion of thyroid hormones in pregnant females causes defective development and maturation of growing baby.
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RELATED QUESTIONS
match the conditions in column A with the cause in column B.
| A (Condition) | B (Cause) | ||
| a | Dwarfism and mental retardation | 1 | shortage of glucose in blood |
| b | Diabetes mellitus | 2 | Over secretion of growth hormone |
| c | Excess of glucose in blood | 3 | Insulin shock |
| d | Gigantism | 4 | Over secretion of thyroxine |
| e | Enlargement of breasts in adult males | 5 | Hypothyroidism |
| f | Exophthalmic goitre | 6 | Over secretion of cortical hormones |
Name the hormone produced by the following gland giving one function: Thyroid
People living in hilly regions usually suffer from simple goitre. Explain.
Goiter is usually observed in people living in hilly regions.
Fill in the Blanks:
______ is a disease caused by hypoparathyroidism.
Which is the only gland that stores its hormones?
Write the functions of thyroid hormones.
Match the items given in Column I with the most appropriate ones in Column II and rewrite the correct Matching pairs:
| Column I | Column II | ||
| (a) | Hyposecretion of Thyroxine in adults | 1. | Diabetes insipidus |
| (b) | Hyposecretion of Insulin | 2. | Myxedema |
| (c) | Hypersecretion of Growth Hormone in Childhood | 3. | Dwarfism |
| (d) | Hyposecretion of ADH | 4. | Gigantism |
| (e) | Hypersecretion of Thyroxine | 5. | Diabetes mellitus |
| 6. | Exophthalmic goitre | ||
| 7. | Cretinism | ||
Name the mineral element required for the synthesis of thyroxine.
