The renin-angiotensin-aldosterone system (RAAS) is essential in regulating blood pressure. Which of the following hormones involved in RAAS is produced by the kidney?

Correct Answer: A

Rationale: Rationale: Renin is produced and released by the kidney in response to low blood pressure or low sodium levels. Renin initiates the RAAS cascade by converting angiotensinogen to angiotensin I. Angiotensin I is then converted to angiotensin II, leading to vasoconstriction and aldosterone release. Aldosterone, produced by the adrenal glands, promotes sodium and water retention. Therefore, choice A is correct as renin is the hormone produced by the kidney to regulate blood pressure. Choices B, C, and D are incorrect as they are downstream products of the RAAS cascade and are not directly produced by the kidney.

Correct Answer: C

Rationale: The correct answer is C: Bear down when the examiner's finger is at the inguinal canal. This action increases intra-abdominal pressure, which helps to push out any potential hernia through the inguinal canal for easier detection. Holding his breath (A) would not facilitate hernia detection. Coughing after insertion (B) is used for rectal exams, not hernia assessment. Relaxing in a supine position (D) is not helpful for hernia examination as it does not aid in hernia protrusion.

Correct Answer: A

Rationale: The correct answer is A: Isoniazid. Isoniazid inhibits the synthesis of mycolic acid, a crucial component of mycobacterial cell walls. If used alone, resistance can develop rapidly due to its specific mechanism of action. Rifampicin (B) acts on RNA polymerase, not mycolic acid synthesis. Pyrazinamide (C) targets mycobacteria in acidic environments, not mycolic acid. Ethambutol (D) inhibits arabinosyltransferase, not mycolic acid synthesis.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Minocycline is known to cause vestibular toxicity due to its lipophilicity and ability to accumulate in inner ear structures. 2. Vestibular toxicity can manifest as dizziness, vertigo, and imbalance. 3. Doxycycline, oxytetracycline, and demeclocycline are less likely to cause vestibular toxicity. 4. Doxycycline is commonly used and well-tolerated, oxytetracycline has a different side effect profile, and demeclocycline is primarily associated with nephrotoxicity. Summary: Choice C (Minocycline) is correct due to its propensity for causing vestibular toxicity. Choices A, B, and D are incorrect as they are less likely to cause this specific adverse effect.

Correct Answer: C

Rationale: The correct answer is Cefotaxime (C) because it is a third-generation cephalosporin with excellent penetration into the cerebrospinal fluid, making it effective against bacterial meningitis pathogens. Cefotaxime covers a broad spectrum of bacteria commonly causing meningitis, including Streptococcus pneumoniae and Neisseria meningitidis. A: Cefuroxime (A) is not the best choice as it has limited activity against some of the common pathogens causing meningitis. B: Cephalexin (B) is a first-generation cephalosporin with poor central nervous system penetration and limited activity against meningitis pathogens. D: Cefdinir (D) is a third-generation cephalosporin but is not the preferred choice for treating bacterial meningitis due to its inferior CNS penetration compared to cefotaxime.