Tag: thyroid, parathyroid and thymus gland

Questions Related to thyroid, parathyroid and thymus gland

A person is having problem with calcium and phosphorus metabolism in his body. Which one of the following glands may not be functioning properly?

zoology endocrine system and chemical co-ordination parathyroid gland thyroid and parathyroid gland thyroid, parathyroid and thymus gland

  1. Parotid

  2. Pancreas

  3. Adrenal cortex

  4. Parathyroid

Show answer
Correct Option: D
Explanation:

Parathyroid glands located behind the thyroid gland, produce a hormone called parathormone. This hormone maintains calcium and phosphorus balance in the body. Thus, if a person is having problem with calcium and phosphorus metabolism in the body, this means, his parathyroid glands are not functioning properly.

Which of the following is the target of parathyroid hormone?

zoology endocrine system and chemical co-ordination parathyroid gland thyroid and parathyroid gland thyroid, parathyroid and thymus gland

  1. Kidneys

  2. Bones

  3. Small intestine

  4. Pancreas

  5. All of the above

Show answer
Correct Option: D
Explanation:

Parathyroid hormone regulates the level of calcium in the blood. It does this through its actions on the kidneys, bones and intestine. When  the blood calcium level is too low, the parathyroid glands release more parathyroid hormone (PTH). This causes the bones to release more calcium into the blood, increase the absorption of more calcium through food and reduces the amount of calcium released by the kidneys into the urine. 

Goitre can occur as a consequence of all the following except

zoology endocrine system and chemical co-ordination parathyroid gland thyroid and parathyroid gland thyroid, parathyroid and thymus gland

  1. Iodine deficiency

  2. Pituitary adenoma

  3. Grave's disease

  4. Excessive intake of exogenous thyroxine

Show answer
Correct Option: D
Explanation:
A goitre is an enlargement of the thyroid gland. The thyroid gland is controlled by the pituitary gland. The pituitary prompts the thyroid to make its hormones including thyroxine ($T _4$) and triiodothyronine ($T _3$) by releasing thyroid-stimulating hormone (TSH). If a person's diet is low in iodine, the thyroid gland enlarges as it attempts to comply with the pituitary's demands. Another common cause is Graves disease, in which the immune system produces antibodies that act like TSH and stimulate the thyroid gland uncontrollably. The gland responds by producing an excessive amount of hormones. Thyrotropin (TSH) secreting pituitary adenomas are a rare cause of hyperthyroidism. Therefore, the correct answer is option D.

In order to determine the effect of each substance on normal body variables, they were injected intravenously. The results are shown in table below. Assume that enough time was allowed between injections so that the substances do not interfere with one another. Based on the information in table above, which of the following is most likely substance B?

Variable Baseline values Values after injecting substance A    Values after injecting substance B    Values after injecting substance C   Values after injecting substance D
Serum ${ Ca }^{ ++ }$ 2.3mmol/L 2.3mmol/L 2.3mmol/L 3.0mmol/L 2.3mmol/L
Serum ${ Na }^{ + }$ 135mmol/L 135mmol/L 135mmol/L 136mmol/L 135mmol/L
Serum glucose 5.6mmol/L 3.3mmol/L 5.6mmol/L 7.4mmol/L 5.6mmol/L

Based on the information in table above, which of the following is most likely substance A?

zoology endocrine system and chemical co-ordination parathyroid gland thyroid and parathyroid gland thyroid, parathyroid and thymus gland

  1. Glucagon

  2. Aldosterone

  3. Calcitonin

  4. Parathyroid hormone

  5. Insulin

Show answer
Correct Option: E
Explanation:

Homeostasis is the process wherein normal body variables are actively regulated inside a defined environment to remain very near to constant. The regulation of  concentration of sodium ($Na^+$) and Calcium ($Ca^{++}$) ions in the blood as well as  glucose levels in blood plasma are examples of Homeostasis.
In the human body, the concentration of blood sugar levels is regulated by the  beta cells of the pancreatic islets by secreting insulin into the blood and inhibits the secretion of glucagon into the blood. The table given in the question shows the effect of a substance on the normal body variables after an intravenous injection of the same. According to the given data,  the  injection of substance A tends to decrease the concentration of Serum glucose below the baseline value. Hence, the substance that was injected is identified as insulin.

In order to determine the effect of each substance on normal body variables, they were injected intravenously. The results are shown in the table below. Assume that enough time was allowed between injections so that the substances do not interfere with one another.

Variable Baseline values Values after injecting substance A Values after injecting substance B Values after injecting substance C Values after injecting substance D
Serum ${ Ca }^{ ++ }$ 2.3mmol/L 2.3mmol/L 3.0mmoL/L 2.3mmol/L 2.3mmol/L
Serum ${ Na }^{ + }$ 135mmol/L 135mmol/L 136mmol/L 135mmol/L 135mmol/L
Serum glucose 5.6mmol/L 3.3mmol/L 5.6mmol/L 7.4mmol/L 5.6mmol/L

Based on the information in Table above, which of the following is most likely substance B?

zoology endocrine system and chemical co-ordination parathyroid gland thyroid and parathyroid gland thyroid, parathyroid and thymus gland

  1. Calcitonin

  2. Insulin

  3. Parathyroid hormone

  4. Glucagon

  5. Aldosterone

Show answer
Correct Option: C
Explanation:
Homeostasis is the process wherein  normal body variables are actively regulated inside a defined environment to remain very near to constant. The regulation of the concentration of sodium (Na+) and calcium ($Ca^{++}$) ions in the blood, as well as glucose levels in blood plasma, are examples of Homeostasis. Each of the variables is controlled by a homeostat or regulator which are energy consuming physiological mechanisms of the body. The table given in the question shows the effect of a substance on the normal body variables after an intravenous injection of the same. According to the given data, since injection of substance B tends to increase the concentration of $Ca^{++}$, it is a parathyroid hormone. 
The plasma ionized calcium ($Ca^{++}$) concentration is very tightly controlled by a pair of homeostats- the parathyroid glands and the parafollicular cells of the thyroid gland. Parathyroid hormone is secreted by the parathyroid glands in the case of a fall in the $Ca^{++}$ levels.