Nokea
Which of the following elements is required for the synthesis of thyroid hormone?
- A. copper
- B. iodine
- C. sulfur
- D. zinc
Correct Answer: B
Rationale: The correct answer is B: iodine. Iodine is an essential element required for the synthesis of thyroid hormone. Thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) contain iodine atoms. Without sufficient iodine, the thyroid gland cannot produce these hormones, leading to thyroid disorders like hypothyroidism or goiter. Copper (A), sulfur (C), and zinc (D) are not directly involved in the synthesis of thyroid hormone. Copper is important for enzyme function, sulfur is present in amino acids, and zinc is involved in various cellular processes but not specifically in thyroid hormone synthesis.
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Enlargement of the thyroid gland:
- A. is called a goiter.
- B. causes Addisonian crisis.
- C. makes a person appear cushingoid.
- D. causes hypocalcemic tetany.
Correct Answer: A
Rationale: Step-by-step rationale for why choice A is correct:
1. Enlargement of the thyroid gland is known as a goiter.
2. A goiter can result from various conditions like iodine deficiency or thyroid disorders.
3. It is a common sign of thyroid dysfunction.
4. Goiter may or may not cause symptoms depending on the underlying cause.
5. Therefore, choice A is the correct answer.
Summary:
- Choice B (Addisonian crisis) is incorrect as it is associated with adrenal insufficiency, not thyroid enlargement.
- Choice C (cushingoid appearance) is incorrect as it is related to excess cortisol production, not thyroid enlargement.
- Choice D (hypocalcemic tetany) is incorrect as it is due to low calcium levels, not thyroid enlargement.
Which pair contains two of these colours in order of increasing frequency (lower frequency first)?
- A. green, red
- B. green, violet
- C. violet, yellow
- D. yellow, red
Correct Answer: B
Rationale: The correct answer is B (green, violet) because green has a lower frequency than violet in the visible light spectrum. Green light has a wavelength longer than violet light, meaning it has lower frequency. This is based on the electromagnetic spectrum where colors are arranged in order of increasing frequency from red (lowest) to violet (highest). Other choices are incorrect because they do not follow the order of increasing frequency as per the visible light spectrum.
This hormone stimulates osteoclastic activity, causing bone resorption.
- A. Calcitonin
- B. Androgen
- C. PTH
- D. Thyroxine
Correct Answer: C
Rationale: The correct answer is C: PTH. Parathyroid hormone (PTH) stimulates osteoclastic activity, leading to bone resorption. PTH plays a crucial role in regulating calcium levels in the blood. When calcium levels are low, PTH is released to stimulate the release of calcium from bones through osteoclast activity.
A: Calcitonin actually inhibits osteoclastic activity, promoting bone formation.
B: Androgen is a male sex hormone and does not directly influence bone resorption.
D: Thyroxine is a thyroid hormone that regulates metabolism and does not directly affect bone resorption.
Where does the middle thyroid vein drain?
- A. Brachiocephalic vein
- B. External jugular vein
- C. Internal jugular vein
- D. Subclavian vein
Correct Answer: C
Rationale: The middle thyroid vein drains into the internal jugular vein due to its anatomical location in the neck. The internal jugular vein receives blood from the brain, face, and neck, making it a suitable drainage site for the thyroid gland. The other options (A, B, D) are incorrect because the brachiocephalic vein drains the upper body, the external jugular vein drains the scalp and face, and the subclavian vein drains the upper extremities, none of which are anatomically linked to the thyroid gland.
Secretion of oxytocin is increased by
- A. milk ejection
- B. dilation of the cervix
- C. increased prolactin levels
- D. increased extracellular fluid (ECF) volume
Correct Answer: B
Rationale: Certainly! The secretion of oxytocin is increased by the dilation of the cervix. When the cervix dilates during childbirth, it triggers the release of oxytocin from the posterior pituitary gland. This hormone plays a crucial role in stimulating uterine contractions during labor and delivery. Milk ejection (choice A) is primarily regulated by oxytocin but does not directly increase its secretion. Increased prolactin levels (choice C) stimulate milk production, not oxytocin secretion. Increased extracellular fluid (ECF) volume (choice D) is not directly related to oxytocin secretion.