Nokea
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.
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Which of the following is true about the endocrine system compared to the nervous system?
- A. A single hormone can target many different responses, whereas a nerve only targets a single response.
- B. Blood can carry all the same hormones throughout the body simultaneously, producing responses all over the body; nerve cells can only target a small number of cells.
- C. Nerve cells and blood work together. The endocrine has nothing to do with the nervous system.
- D. Endocrine hormones only target a very small number of precise responses.
Correct Answer: B
Rationale: The correct answer is B because the endocrine system releases hormones into the bloodstream, allowing them to reach all parts of the body simultaneously and produce widespread responses. In contrast, the nervous system sends signals through nerve cells, which can only target a small number of specific cells. This difference in distribution and reach of signals is a key distinction between the endocrine and nervous systems.
Choice A is incorrect because a single hormone can indeed target multiple responses in different parts of the body, similar to how a nerve signal can affect multiple cells along its path.
Choice C is incorrect as nerve cells and the endocrine system can interact and influence each other's functions, such as in the case of stress response involving both systems.
Choice D is incorrect because endocrine hormones can have broad effects on various organs and tissues, not limited to a small number of precise responses.
Which is not Na+ dependent for absorption?
- A. thiamin
- B. riboflavin
- C. niacin
- D. folate
Correct Answer: D
Rationale: The correct answer is D. Folate absorption is not Na+ dependent because it is absorbed in the small intestine through a carrier-mediated process independent of sodium. Thiamin, riboflavin, and niacin require sodium-dependent transport mechanisms for absorption in the small intestine. Thiamin is absorbed through thiamin transporters that are Na+ dependent. Riboflavin is absorbed by sodium-dependent multivitamin transporters. Niacin absorption also involves sodium-dependent transporters. Therefore, folate is the only option that is not Na+ dependent for absorption.
In the adrenal medulla:
- A. epinephrine is formed by the hydroxylation and decarboxylation of tyrosine
- B. 10% of the cells are the epinephrine-secreting type
- C. plasma norepinephrine levels are generally unchanged after adrenalectomy
- D. catecholamine t1/2 is 10 minutes in the circulation
Correct Answer: C
Rationale: Rationale for Choice C: Plasma norepinephrine levels are generally unchanged after adrenalectomy in the adrenal medulla because norepinephrine is mainly produced by postganglionic sympathetic nerve endings rather than the adrenal medulla. Adrenalectomy removes the adrenal gland, which primarily secretes epinephrine, not norepinephrine. Therefore, plasma norepinephrine levels would not be significantly affected by adrenalectomy.
Summary of other choices:
A: Incorrect. Epinephrine is formed from norepinephrine, not tyrosine, through methylation and hydroxylation.
B: Incorrect. The majority of cells in the adrenal medulla are epinephrine-secreting cells, not just 10%.
D: Incorrect. The half-life of catecholamines in the circulation is very short, around 2 minutes, not 10 minutes.
Which of the following is most descriptive of cAMP?
- A. Second chemical messenger
- B. Catecholamine that contributes to the fight-or-flight response
- C. Steroid
- D. Releasing hormone
Correct Answer: A
Rationale: The correct answer is A: Second chemical messenger. cAMP is a second messenger in cellular signaling pathways, relaying signals from extracellular molecules to intracellular targets. It is not a catecholamine (B), steroid (C), or releasing hormone (D). Catecholamines are a class of neurotransmitters, steroids are lipids with different functions, and releasing hormones are secreted by the hypothalamus to stimulate the release of other hormones. Thus, the most descriptive term for cAMP is a second chemical messenger.
Name the gland that is located at the base of the throat, just inferior to the laryngeal prominence (Adam's apple).
- A. Pituitary.
- B. Pineal gland.
- C. Hypothalamus.
- D. Thyroid.
Correct Answer: D
Rationale: The correct answer is D: Thyroid. The thyroid gland is located at the base of the throat, just below the Adam's apple. It is responsible for producing thyroid hormones that regulate metabolism and various bodily functions. The pituitary gland (A) is located in the brain, the pineal gland (B) is located in the brain as well, and the hypothalamus (C) is also in the brain. These glands play crucial roles in hormone regulation, but they are not located at the base of the throat like the thyroid gland.