Which tracheal rings are generally related to isthmus?

Correct Answer: C

Rationale: Rationale: The isthmus of the thyroid gland is located between the 2nd and 3rd tracheal rings. These rings provide support to the trachea and help maintain its shape. Therefore, the correct answer is C. Summary of other choices: A: 1st and 2nd - Incorrect, as the isthmus is not related to the 1st tracheal ring. B: 1st, 2nd and 3rd - Incorrect, as the isthmus is only between the 2nd and 3rd tracheal rings. D: 2nd, 3rd and 4th - Incorrect, as the isthmus does not extend to the 4th tracheal ring.

Correct Answer: C

Rationale: The correct answer is C because the hypothalamus does not directly secrete ACTH, TSH, and gonadotropins. It secretes releasing hormones that regulate the secretion of these hormones from the anterior pituitary gland. Choice A and B are correct because the hypothalamus does secrete releasing hormones and controls the anterior pituitary gland. Choice D is incorrect because the hypothalamus synthesizes oxytocin and ADH, which are stored in the posterior pituitary gland.

Correct Answer: D

Rationale: The correct answer is D, the anterior pituitary gland, because it secretes TSH, ACTH, and growth hormone. The anterior pituitary gland is also known as the adenohypophysis, and it plays a key role in regulating various bodily functions through the release of different hormones. The other choices are incorrect because the neurohypophysis (choice A) secretes hormones like oxytocin and vasopressin, the pancreas (choice B) secretes insulin and glucagon, and the adrenal medulla (choice C) secretes adrenaline and noradrenaline.

Correct Answer: D

Rationale: Correct Answer: D Rationale: Calcitonin and parathyroid hormone regulate plasma calcium levels. Calcitonin decreases calcium levels by inhibiting bone breakdown, while parathyroid hormone increases calcium levels by stimulating bone breakdown and increasing calcium reabsorption. Therefore, both hormones work together to maintain calcium homeostasis. The correct answer, choice D, highlights that both hormones control plasma calcium levels. Summary of Other Choices: A: Incorrect. Calcitonin is secreted by the thyroid gland, not the parathyroid glands. B: Incorrect. Calcitonin decreases plasma calcium levels, while parathyroid hormone increases plasma calcium levels. C: Incorrect. Parathyroid hormone increases plasma calcium levels, whereas calcitonin decreases plasma calcium levels.

Correct Answer: D

Rationale: Step 1: Cretinism, myxedema, and Graves' disease are all related to thyroid gland function. Step 2: Cretinism is a congenital hypothyroidism, myxedema is adult hypothyroidism, and Graves' disease is hyperthyroidism. Step 3: Thus, they are all disorders of thyroid gland function. Summary: - Choice A is incorrect because they are not all thyroid hormone deficiency diseases. - Choice B is incorrect because they are not all caused by oversecretion of thyroxine. - Choice C is incorrect because they are not primarily related to calcium imbalances due to lack of calcitonin.