Chemical Coordination and Integration Test 10

Endostyle is a part found in lower- chordates which are having a function of filtration while feeding. Homologous means similarity. Thyroid glands are found in upper chordates/ vertebrates. So, they both are similar in iodine- concentration activity.

In amphibian metamorphosis, thyroxine (T₄​^- iodine-containing hormone) produced by the thyroid gland causes apoptosis of the cells of gills, tail, and fins of tadpoles. It plays a major role in the amphibian metamorphosis that transforms the vegetarian aquatic tadpole into a carnivorous terrestrial adult frog, with better neurological, visuospatial, olfactory and cognitive abilities for hunting, as seen in other predatory animals. Removal of this organ will arrest the development of tadpole.

Edward C. Kendall isolated thyroxine from the thyroid gland by crystallising glutathione. Thyroxine is a hormone produced by the thyroid gland. it helps to maintain the metabolism of the body. Tyrosine is considered as the precursor molecule for the thyroxine.

So, the correct answer is option D.

Parathyroid hormone, or PTH, is secreted by the parathyroid glands and increases blood levels of calcium by stimulating bones to release calcium, stimulating kidney cells to reclaim calcium from urine before excretion, and increasing calcium absorption by the intestine.

Thyroxine increases the number and activity of mitochondria in cells by binding to the cells' DNA, increasing the basal metabolic rate. Administration of thyroid hormones, such as thyroxine, causes an increase in the rate of carbohydrate and fat metabolism and a rise in the rate of protein synthesis and breakdown.

Myxedema is another term for severely advanced hypothyroidism. This is a condition that occurs when your body doesn't produce enough thyroid hormone. The thyroid is a small gland that sits right at the front of your neck. It releases hormones that help your body regulate energy and control a wide variety of functions.

The parathyroid hormone (PTH), secreted by the parathyroid glands, is responsible for regulating blood calcium levels; it is released whenever blood calcium levels are low. PTH increases blood calcium levels by stimulating osteoclasts, which break down bone to release calcium into the blood stream.

The Thyroid gland is the only endocrine gland that stores its secretory product in large quantities, normally about 10 days supplies in the extracellular space before discharging into the blood. It secretes iodinated hormone i.e., thyroxine and triiodothyronine that are stored in the colloid which fills the follicle cells and released to blood when needed.

Goitre is the enlargement of thyroid gland which occurs due to deficiency of iodine in the body. When the iodine levels are low, thyroid gland becomes hyper active and enlarged to compensate the deficiency of thyroid hormone in the body. The enlarged thyroid gland is visible as a swelling in the throat known as goitre.

Hypocalcemia is the condition of reduced sugar levels in blood.

Hypercalcemia is the condition of increased sugar levels in blood.
Parathormone is secreted from the parathyroid hormone and increases blood calcium level by increasing the reabsorption of calcium from the bones. Hence, its deficiency will lead to decreased sugar levels in blood i.e. hypocalcemia.
So, the correct answer is 'Hypocalcemia'

Cretinism is due to abnormal secretion of thyroxine.

Cretinism is caused by the hypersecretion of thyroid hormone in infants called thyroxine. Thyroxine has markedly reduced metabolic rate and oxidation. This leads to slow heartbeat , lower blood pressure , decrease in body temperature , stunted growth , etc. The disorder can be created by an early administration of thyroid hormones .

Bovine parathormone is a large polypeptide having 84 amino-acids. It was discovered and purified by Philips Collip in 1925

Exophthalmic goitre is an endocrine disorder that is the most common cause of hyperthyroidism (excess secretion of thyroid hormone) and thyrotoxicosis (effects of excess thyroid hormone action in tissue). In this disease the excessive secretion of thyroid hormone is accompanied by diffuse enlargement of the thyroid gland.

The vitamin which works along with parathyroid hormone is Calciferol.

This increase in the concentration  of calcium together with a Vitamin D called Calciferol feeds back to the parathyroid glands to stop further parathyroid hormones released . The production of Vitamin D is also directly regulated by calcium, phosphate and Calcitriol. 

The thyroid gland lies in the neck, in front of the upper part of the trachea. Two types of hormones are produced, which are the iodine containing hormones; tri-iodothyronine (T3​) and thyroxine (T4​). The gland consists of varying sized follicles, which are bounded by a single layer of cuboidal epithelial cells (follicular cells} and a basement membrane, surrounding a central lumen filled with a homogenous protein rich colloid (thyroglobulin).

The colloid is a storage of thyroid hormones prior to secretion. The thyroid gland is the only endocrine gland to store its hormone in large quantities.

Hashimoto's disease is an autoimmune disease and is characterized by destruction of thyroid gland leading to the absence of thyroxin hormone. So, it develops symptoms as that of hyposecretion of thyroxine such as lethargy, hair loss, weight gain, puffed skin, lowered body temperature and slowed pulse rate. Thus, the correct answer is A.

Parathormone of parathyroid gland increases the blood calcium level. Removal of parathyroid gland decreases the blood calcium level due to its increased excretion in urine. It causes increased excitability of muscles and their sustained contraction referred to as parathyroid tetany. Myxedema is caused by hypothyroidism in adults while Addison’s disease is caused by the presence of ineffective ACTH. Simmond's disease is caused by the destruction of the anterior pituitary lobe. Thus, the correct answer is A.

Hypersecretion of parathyroid hormone (PTH) increases serum calcium levels via enhanced bone resorption and renal calcium reabsorption. Due to hypersecretion of parathyroid the bones becomes weaker.

T₃ is less tightly bound to plasma proteins than is T₄ and is therefore more readily available for cellular uptake. T₃ binds to nuclear receptors to a much greater extent than T₄, hence T₃ is more rapidly and biologically active than T₄. T₃ and T4 are deiodinated and deaminated in the tissues.

Metamorphosis occurs as the tadpole tail shrinks and the legs grow. At this time, the tadpole will first grow a pair of hind legs, then a pair of front legs. The body also typically becomes shorter and broader. Tadpoles treated with thyroxine (thyroid hormone) or iodine will develop at an increased rate, whereas tadpoles treated with thiourea, a thyroid-hormone inhibitor, will metamorphose at a slower rate.

Hereditary factors may cause goiters. Risk factors for the development of a goiter include female sex, age over 40 years, inadequate dietary intake of iodine, residence in an endemic area, and a family history of goiter. Symptoms: Thyroid enlargement varying from a single small nodule to massive enlargement (neck lump). But there is no proof of goitres being hereditary. Hence, Option D.

The hormone calcitonin, which is produced by the parafollicular (or C) cells of the thyroid, has the opposite effect on blood calcium levels as PTH. Calcitonin decreases blood calcium levels by inhibiting osteoclasts, stimulating osteoblasts, and stimulating calcium excretion by the kidneys. Hence, Option C.

Thyroxine is the main hormone produced by the thyroid gland which controls the body's basal metabolic rate (BMR).  Every cell in the body depends on thyroid hormones for proper metabolism. Too much thyroxine causes a BMR, that is too high. This leads to Graves' disease, a condition pertaining to an overactive thyroid.

Vitamin D us know as calciferol and it's help in bone formation and if vitamin D is less minimum amount then disease osteoporosis.

Thyrocalcitonin also known as calcitonin is a polypeptide hormone secreted by the parafollicular or C cells of the thyroid gland. It lowers the levels of calcium and phosphate in the blood and promotes the formation of bone. Thus, the correct answer is option A.