A 15 year old high school football player is in your clinic, c/o severe testicular pain since 8 am this morning. Denies sexual activity. Unable to urinate due to pain. He is nauseated and is vomiting. He is lying on the exam table, uncomfortably shifting his position. His BP is 150/100, pulse is 110, respirations are 24. There are no lesions on the penis and no discharge from the meatus. The scrotal skin is tense and red. Palpation of the left testicle causes severe pain and the patient begins to cry. Prostate exam is normal. His cremasteric reflex is absent on the left but is normal on the right. Urine sample (by catheter) is normal. You send him to the emergency room. What is the most likely diagnosis?

Correct Answer: C

Rationale: The correct diagnosis is torsion of the spermatic cord. This condition presents with sudden severe testicular pain, nausea, vomiting, high blood pressure, tachycardia, and absence of cremasteric reflex. The key findings include red, tense scrotal skin, severe pain on palpation, and crying. The absence of discharge and normal prostate exam rule out prostatitis. Acute orchitis typically presents with fever and urinary symptoms, which are absent here. Acute epididymitis usually presents with gradual onset and urinary symptoms. Torsion of the spermatic cord is a surgical emergency requiring immediate intervention to prevent testicular ischemia and necrosis.

Correct Answer: D

Rationale: The correct answer is D: Her plasma estrogen concentration is very low. The absence of menstrual cycles in a young athlete with normal bone density suggests hypothalamic dysfunction affecting the menstrual cycle. This can result from low estrogen levels, which are essential for the regulation of menstrual cycles. Low estrogen levels can be caused by intense physical activity, leading to suppression of the hypothalamic-pituitary-ovarian axis. Choice A is incorrect because a high-carbohydrate diet alone is unlikely to cause amenorrhea. Choice B is irrelevant to the absence of menstrual cycles and normal bone density in the athlete. Choice C, elevated blood pressure, is also unrelated to the situation described.

Correct Answer: D

Rationale: Step 1: Increased binding of a hormone to plasma proteins reduces the concentration of free hormone in the blood. Step 2: With decreased free hormone levels, there is less hormone available to exert its effects. Step 3: This reduction in free hormone would lead to an increase in the degree of negative feedback exerted by the hormone to regulate its own production. Therefore, the correct answer is D. Summary: A: Increase in plasma clearance of the hormone - Incorrect. Increased binding to plasma proteins would decrease clearance. B: Decrease in half-life of the hormone - Incorrect. Increased binding can prolong the half-life by protecting the hormone from degradation. C: Increase in hormone activity - Incorrect. Increased binding reduces the availability of free hormone, decreasing its activity.

Correct Answer: D

Rationale: The correct answer is D: Ampulla of the fallopian tubes. Fertilization typically occurs in the ampulla of the fallopian tubes, where the sperm meets the egg. The ampulla is the widest part of the fallopian tube, providing the necessary space for fertilization to occur. Sperm must travel through the cervix and uterus to reach the fallopian tubes where fertilization takes place. The ovary is where the egg is released during ovulation but fertilization occurs in the fallopian tubes.

Correct Answer: D

Rationale: The correct answer is D because menopause occurs when the ovaries run out of follicles, which are needed for ovulation and hormone production. This leads to reduced estrogen levels and cessation of menstrual cycles. Choices A and B focus on hormone levels and follicle responsiveness, not the actual follicle count. Choice C is incorrect as progesterone is mainly produced by the corpus luteum after ovulation, not the primary cause of menopause.