Male sexual physiology — MCQs

Fertilization begins when sperm binds to the corona radiata of the egg. Once the sperm enters the cytoplasm, a cortical reaction occurs which prevents other sperm from entering the oocyte. The oocyte then undergoes an important reaction. What is the next reaction that is necessary for fertilization to continue?

A 58-year-old man comes to the physician for a 2-month history of increased urinary frequency. Urodynamic testing shows a urinary flow rate of 11 mL/s (N>15) and a postvoid residual volume of 65 mL (N<50). Prostate-specific antigen level is 3.2 ng/mL (N<4). Treatment with a drug that also increases scalp hair regrowth is initiated. Which of the following is the most likely mechanism of action of this drug?

A 76-year-old male presents to his primary care physician because he is concerned about changes in urination. Over the last few months, he has noticed increased urinary frequency as well as difficulty with initiating and stopping urination. He denies having pain with urination. Physical exam reveals a uniformly enlarged and non-tender prostate. Lab tests showed that the prostate specific antigen (PSA) was within normal limits. The patient did not tolerate an alpha blocker due to episodes of syncope so another medication is prescribed that affects testosterone metabolism. Which of the following disorders can also be treated with the medication most likely prescribed in this case?

A 70-year-old male presents to his primary care provider complaining of decreased sexual function. He reports that over the past several years, he has noted a gradual decline in his ability to sustain an erection. He used to wake up with erections but no longer does. His past medical history is notable for diabetes, hyperlipidemia, and a prior myocardial infarction. He takes metformin, glyburide, aspirin, and atorvastatin. He drinks 2-3 drinks per week and has a 25 pack-year smoking history. He has been happily married for 40 years. He retired from his job as a construction worker 5 years ago and has been enjoying retirement with his wife. His physician recommends starting a medication that is also used in the treatment of pulmonary hypertension. Which of the following is a downstream effect of this medication?

A 47-year-old man presents to the physician’s office with an inability to maintain an erection. He can achieve an erection, but it is brief and decreases soon after the penetration. His erectile dysfunction developed gradually over the past 2 years. He denies decreased libido, depressed mood, or anhedonia. He does not report any chronic conditions. He has a 20-pack-year history of smoking and drinks alcohol occasionally. He weighs 120 kg (264.5 lb), his height is 181 cm (5 ft 11 in), and his waist circumference is 110 cm (43 in). The blood pressure is 145/90 mm Hg and the heart rate is 86/min. Physical examination is performed including a genitourinary and rectal examination. It reveals no abnormalities besides central obesity. Which of the following laboratory tests is indicated to investigate for the cause of the patient’s condition?

A 27-year-old woman comes to the physician for the evaluation of infertility. She has been unable to conceive for the past 2 years. Menses occur at 45 to 80-day intervals. She is 168 cm (5 ft 6 in) tall and weighs 77 kg (170 lb); BMI is 27.4 kg/m2. Physical examination shows facial acne and pigmented hair on the upper lip. Serum studies show elevated levels of testosterone and an LH:FSH ratio of 4:1. Treatment with the appropriate drug for this patient's infertility is begun. Which of the following is the primary mechanism of action of this drug?

A 56-year-old man comes to the clinic complaining of sexual dysfunction. He reports normal sexual function until 4 months ago when his relationship with his wife became stressful due to a death in the family. When asked about the details of his dysfunction, he claims that he is “able to get it up, but just can’t finish the job.” He denies any decrease in libido or erections, endorses morning erections, but an inability to ejaculate. He is an avid cyclist and exercises regularly. His past medical history includes depression and diabetes, for which he takes citalopram and metformin, respectively. A physical examination is unremarkable. What is the most likely explanation for this patient’s symptoms?

A couple brings their 1-year-old child to a medical office for a follow-up evaluation of his small, empty scrotum. The scrotum has been empty since birth and the physician asked them to follow up with a pediatrician. There are no other complaints. The immunization history is up to date and his growth and development have been excellent. On examination, he is a playful, active child with a left, non-reducible, non-tender inguinal mass, an empty and poorly rugated hemiscrotal sac, and a testis within the right hemiscrotal sac. Which of the following hormones would likely be deficient in this patient by puberty if the condition is left untreated?

A 51-year-old man presents to his physician with decreased libido and inability to achieve an erection. He also reports poor sleep, loss of pleasure to do his job, and depressed mood. His symptoms started a year ago, soon after his wife got into the car accident. She survived and recovered with the minimal deficit, but the patient still feels guilty due to this case. The patient was diagnosed with diabetes 6 months ago, but he does not take any medications for it. He denies any other conditions. His weight is 105 kg (231.5 lb), his height is 172 cm (5 ft 7 in), and his waist circumference is 106 cm. The blood pressure is 150/90 mm Hg, and the heart rate is 73/min. The physical examination only shows increased adiposity. Which of the following tests is specifically intended to distinguish between the organic and psychogenic cause of the patient’s condition?

Research is being conducted on embryoblasts. The exact date of fertilization is unknown. There is the presence of a cytotrophoblast and syncytiotrophoblast, marking the time when implantation into the uterus would normally occur. Within the embryoblast, columnar and cuboidal cells are separated by a membrane. Which of these cell layers begins to line the yolk sac cavity?