Physiology - An Illustrated Review
Questions & Answers
1. Klinefelter’s syndrome is a genetic disorder in which the patient has three sex chromosomes. Which of the following statements is true about patients with Klinefelter’s syndrome?
A. The karyotype is XYY
B. The patient is at decreased risk of developing osteoporosis.
C. The patient has normal muscle mass and body hair.
D. Puberty will occur at approximately the normal age.
E. Testosterone should be prescribed at puberty.
2. Turner’s syndrome is caused by the absence of one of the sex hormones. Which of the following statements is true about patients with Turner’s syndrome?
A. They are fertile
B. They have normal stature
C. They are sometimes female
D. They are hermaphrodities (have both male and female reproductive organs)
E. They are at risk for serious vascular complications
3. Antimüllerian hormone (AMH) is
A. secreted in response to human chorionic gonadotropin (hCG).
B. synthesized and secreted by fetal Sertoli cells.
C. required for differentiation of the wolffian ducts.
D. synthesized and secreted by interstitial Leydig cells.
E. important for differentiation of female internal genitalia.
4. Testosterone is
A. present in the plasma as a free hormone not bound to plasma proteins.
B. not required for the initiation and maintenance of spermatogenesis.
C. synthesized from estradiol-17β in the testes.
D. converted to dihydrotestosterone (DHT) by 5α-reductase in the cells of the prostate gland and other target cells.
E. produced primarily in the Sertoli cells of the testes in response to follicle-stimulating hormone (FSH).
5. Onset of menses is associated with
A. decreased progesterone.
B. increased estrogen.
C. increased LH.
D. increased FSH.
E. dilation of endometrial blood vessels.
6. The ovarian follicle
A. can grow to maturation without FSH.
B. cannot grow without locally produced androgens.
C. secretes estradiol in response to FSH and LH.
D. when dominant, releases inhibin, which decreases LH levels.
E. down-regulates LH receptors before ovulation.
7. Fertilization usually occurs in what part of the female reproductive tract?
C. Fallopian tube
E. Corpus luteum
8. Following fertilization, the blastocyst secretes which of the following hormones?
A. Human chorionic gonadotropin (hCG)
B. Human placental lactogen (hPL)
D. Follicle-stimulating hormone (FSH)
E. Luteinizing hormone (LH)
9. A healthy 56-year-old man attends his urologist’s office complaining of the inability to consistently develop an erection and have intercourse with his wife. Physical examination of the external genitalia and prostate are normal, and laboratory tests reveal no hormonal abnormalities or glucose intolerance. He is currently not taking any medication. He is prescribed sildenafil to take one hour before commencing sexual activity. What is the mechanism of action of this drug?
A. Increases the conversion of testosterone from androstenidone in the testes
B. Inhibits 5α-reductase
C. Inhibits cGMP phosphodiesterase
D. Stimulates adenylate cyclase
E. Inhibits cAMP
Questions 10 and 11 refer to the clinical scenario that follows. A 26-year-old woman complains of severe, dull pain and cramping in the lower abdomen. There are no other physical findings. A laparoscopy reveals the presence of ectopic endometrial tissue on the uterine wall and ovaries. Danazol (a synthetic androgen and inhibitor of gonadotropins), 600 mg/day, is prescribed for up to 9 months, with a 50% possibility of conception after withdrawal of the therapy.
10. Her condition is
A. ectopic pregnancy.
C. placental abruption.
D. placenta plevia.
E. pelvic inflammatory disease.
11. The action of danazol
A. stimulates ovulation.
B. stimulates before it inhibits GnRH.
C. produces results that are different from those of combination oral contraceptives.
D. is free of side effects.
E. suppresses growth of abnormal endometrial tissue.
12. A 32 year old woman comes to the emergency department with severe abdominal pain, cramping, and mild, bright red, vaginal bleeding. Her history reveals that she has very irregular periods, the last one being approximately 12 weeks ago, and she is currently undergoing a course of injectable gonadotropins to treat infertility. On examination, her blood pressure is 115/75 mmHg, pulse 76/min, respirations 12/min and her temperature is 37.1°C. She has no rebound abdominal tenderness or guarding. Urinalysis shows that the patient is pregnant, but there are no proteins present in the urine. What is the condition that is most likely to be causing these symptoms?
A. Placental abruption
C. Ectopic pregnancy
D. Placenta previa
E. Acute appendicitis
13. A woman is admitted to the OB-GYN ward for induction of labor. She is three weeks overdue. Twenty-four hours before she is to be induced, she is given an injection of dexamethasone (a glucocorticoid). The purpose of administering this drug is to
A. cause uterine contraction
B. prevent swelling and inflammation of the birth canal
C. induce maturation of the fetal lungs, gut, kidney, and other organs
D. sedate the expectant mother
E. reduce bloating from the retention of water
Questions 14 and 15 refer to the following clinical scenario. By the sixth month of pregnancy, a woman in her 20s feels irregular contractions of the uterus, but no complications are present. After 9 months, a healthy 7 lb, 3 oz girl is delivered with no complications. Breast feeding is planned.
14. Which hormone prevented spontaneous abortion of the implanted embryo?
15. Which hormone is the most important for milk production after birth?
A. Human chorionic gonadotropin (hCG)
B. Human placental lactogen (hPL)
C. Human chorionic thyrotopin (hCT)
16. Polycystic ovarian syndrome (PCOS) can cause infertility in women. Which is a symptom of this disorder?
A. Sparse facial hair
B. Small ovaries
C. Regular periods
E. Normal glucose tolerance
Answers and Explanations
1. E Testosterone replacement therapy may prevent some of the symptoms of the disorder.
A The karyotype is XXY, and the patient appears to be male.
B Osteoporosis is a complication of this disorder.
C The patient lacks muscle mass and body hair.
D Puberty is delayed due to a lack of testosterone.
2. E A serious complication of Turner’s syndrome is aortic dissection, where there is tearing and bleeding between the inner wall and the outer wall of the aorta. Rupture of the outer wall of the aorta is usually fatal
A-C Patients with Turner’s syndrome are often infertile, have short stature, and are always female.
D Patients with Turner’s syndrome have the karyotype XO. Since they lack a Y chromosome, they cannot develop male internal and external genitalia and are therefore not hermaphrodites.
3. B AMH is secreted in response to Sertoli cells and causes regression of the müllerian ducts, an active process in male development (pp. 292–293).
A AMH is not secreted in response to hCG.
C Testosterone stimulates development of wolffian ducts.
D Leydig cells secrete testosterone.
E AMH must be absent for female genitalia to develop.
4. D Testosterone promotes the differentiation of the wolffian ducts and is metabolized to DHT, which causes differentiation of the external genitalia (p. 295).
A Testosterone is bound to plasma proteins, like all steroid hormones are.
B It is required for spermatogenesis.
C Estradiol can be synthesized from testosterone by an aromatase reaction.
E Testosterone is produced in the Leydig cells in response to luteinizing hormone (LH).
5. A If fertilization does not occur, estrogen and progesterone inhibit FSH and LH (C,D), which causes reduced plasma progesterone and estrogen (B) (pp. 304–305).
6. C. Estrogen secretion increases before ovulation due to FSH and especially LH (p. 304).
A Follicles require FSH to mature.
B FSH and LH stimulate androgen synthesis, but local androgens are not required as precursors for estrogen.
D Inhibin negatively feeds back to FSH synthesis.
E LH receptors are up-regulated by estrogen.
7. C Fertilization normally occurs in the ampulla of the fallopian tubes (p. 300).
A The vagina is an organ of copulation and partuition (birth).
B The ovaries secrete the female sex hormones: estrogens (estrone [E1], estradiol [E2], and estriol [E3]), and progesterone.
D The uterus is the site of implantation and incubation and is an organ of parturition (birth).
E The corpus luteum is a temporary endocrine structure that forms from the ovarian follicle during the luteal phase of the menstrual cycle. It secretes large quantities of progesterone that cause the endometrium to thicken and become more vascular and secretory as it prepares the uterus for embryo implantation and pregnancy.
8. A Following fertilization the blastocyst secretes human chorionic gonadotropins (hCG) which maintains the corpus luteum and allows it to produce and secrete the progesterone needed to sustain the pregnancy (p. 305).
B Human placental lactogen (hPL), a hormone produced by the placenta, is very similar in structure and function to growth hormone and prolactin.
C Oxytocin released from the posterior pituitary binds to smooth muscle cell receptors in the uterus, where it stimulates the production of uterine and placental prostaglandins, which, in turn, increase intracellular Ca2+ and promotes contractility.
D The pulsatile release of follicle-stimulating hormone (FSH) from the anterior pituitary is involved in the onset of puberty.
E The pulsatile release of luteinizing hormone (LH) from the anterior pituitary is involved in the onset of puberty.
9. C Sildenafil inhibits cGMP-specific phosphodiesterase type 5 which delays the degradation of cGMP. This maintains the arteriolar dilation of the cavernous sinuses of the penis that are responsible for maintaining an erection. It does not have the actions of the other choices (p. 298).
10. B Endometrial tissue in the abdomen is endometriosis. A In ectopic pregnancy, the fertilized ovum implants outside the uterine cavity.
C In placental abruption, the placenta is separated from the uterus.
D In placenta plevia, the placenta covers the cervix.
E Pelvic inflammatory disease is an inflammation of the fallopian tubes.
11. E Inhibition of FSH and LH reduces estrogen stimulation of the ovaries and growth of endometrial tissue (p. 301).
A Danazol suppresses ovulation.
B Danazol only inhibits GnRH; GnRH agonists stimulate release of LH and FSH before they suppress GnRH secretion by negative feedback.
C Oral contraceptives inhibit FSH and LH by negative feedback, so they can also be used to treat endometriosis.
D Danazol causes masculinization and other adverse effects.
12. C This patient is showing signs of ectopic pregnancy when the fertilized ovum develops outside the uterine cavity, usually in the fallopian tubes. This is more likely to occur in women taking fertility drugs for ovulation.
A Placental abruption is separation of the placenta from the uterus. It is unlikely in this case as the vaginal blood is bright red (in placental abruption it is usually darker) and there is no shock.
B Pre-eclampsia is a disorder of hypertension, proteinuria, and edema in pregnancy, usually in the third trimester. There is no evidence of this triad of symptoms in this patient.
D Placenta previa is a condition when the placenta lies low in the uterus, partially or completely covering the cervix. Dilation of the cervix later in pregnancy can cause vaginal blood loss. This diagnosis is unlikely, since placenta previa is usually painless.
E Acute appendicitis usually presents with colicky, central abdominal pain that then focuses on a point in the right lower quadrant (McBurney’s point) as the inflammation of the appendix spreads to the overlying peritoneum. The patient will have a fever, and there will be rebound tenderness and guarding of the abdomen on palpation. The lack of these symptoms makes this diagnosis unlikely.
13. C Glucocorticoids facilitate organ maturation, e.g., they promote surfactant development in the lungs (pp. 130, 274, 308).
A Oxytocin and prostaglandins promote uterine contraction.
B Glucocorticoids reduce inflammation, but they are not used prophylactically.
D Glucocorticoids have no sedative action.
E A diuretic would reduce retention of water.
14. B High levels of progesterone maintain pregnancy and prevent myometrial contraction (p. 301).
A Estrogen levels are high, but it promotes uterine contractions.
C Oxytocin stimulates uterine contractions.
D Prostaglandins are important for parturition and menses.
E Prolactin suppresses GnRH secretion.
15. D Prolactin stimulates milk production and is released in response to suckling (pp. 311–312).
A hCG stimulates steroid production in the first trimester.
B Although hPL stimulates milk production, it is less important than prolactin.
C hCT resembles thyroid-stimulating hormone, but is a placental hormone.
E Oxytocin stimulates synthesis of galactose in the mammary glands but not milk volume.
16. D Obesity is a common symptom (p. 301).
A,C Excess facial hair and irregular periods are common symptoms
B Small ovaries are not a common symptom of polycystic ovarian syndrome (PCOS). As the name suggests, women with this condition have large, polycystic ovaries due to failure of ovarian follicles to rupture.
E Type 2 diabetes is a complication of PCOS which causes abnormal glucose tolerance.