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From fertilization to week 8 of proliferative phase of the uterine pregnancy, the conceptus is called (menstrual) cycle? ________.
- A. estrogens
- B. a fetus
- C. progesterones
- D. an embryo
Correct Answer: D
Rationale: The correct answer is D: an embryo. From fertilization to week 8 of the proliferative phase of uterine pregnancy, the conceptus is referred to as an embryo. This is because during this period, the fertilized egg undergoes rapid cell division and differentiation, leading to the formation of distinct embryonic structures and the beginning of organ development. The term "fetus" is used after the embryonic stage, typically from week 9 onwards. Choices A and C, estrogens and progesterones respectively, are hormones involved in regulating the menstrual cycle and maintaining pregnancy but are not terms used to describe the developing conceptus itself during this specific timeframe.
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A scientist studying developmental physiology performs an experiment in which a substance is given to pregnant rats that give birth to pups that have XY chromosomes but female genital organs. What was the substance given to the rats?
- A. An antibody that blocked the effect of human chorionic gonadotropin in the embryo and fetus
- B. A large quantity of estrogen-like compounds
- C. Follicle-stimulating hormone
- D. Testosterone
Correct Answer: A
Rationale: The correct answer is A: An antibody that blocked the effect of human chorionic gonadotropin in the embryo and fetus. Human chorionic gonadotropin (hCG) is crucial for male sexual differentiation. Blocking its effects would lead to the development of female genital organs in pups with XY chromosomes. Estrogen-like compounds (B) and follicle-stimulating hormone (C) are not directly involved in male sexual differentiation. Testosterone (D) is responsible for male sexual development, so giving testosterone would not result in female genital organs in XY pups.
A man who has been exposed to high levels of gamma radiation is sterile due to destruction of the germinal epithelium of the seminiferous tubules, although he has normal levels of testosterone. Which of the following would be found in this patient?
- A. Normal secretory pattern of gonadotropin-releasing hormone
- B. Normal levels of inhibin
- C. Suppressed levels of follicle-stimulating hormone
- D. Absence of Leydig cells
Correct Answer: A
Rationale: Step 1: High levels of gamma radiation cause destruction of germinal epithelium, leading to infertility.
Step 2: Normal testosterone levels indicate intact Leydig cells, responsible for testosterone production.
Step 3: Normal secretory pattern of gonadotropin-releasing hormone (GnRH) is expected as it regulates pituitary hormone secretion.
Step 4: Inhibin is produced by Sertoli cells (part of germinal epithelium) and would be decreased due to destruction.
Step 5: Follicle-stimulating hormone (FSH) levels would be elevated, not suppressed, due to lack of inhibin feedback.
Step 6: Leydig cells are intact, so Leydig cells are not absent in this scenario.
The nurse will plan to teach a 51-yr-old man who is scheduled for an annual physical examination about a(n)
- A. increased risk for testicular cancer.
- B. possible changes in erectile function.
- C. normal decreases in testosterone level.
- D. prostate specific antigen (PSA) testing.
Correct Answer: C
Rationale: The correct answer is C: normal decreases in testosterone level. At the age of 51, it is important to educate the man about the normal age-related decline in testosterone levels, which can affect various aspects of health. This information will help manage expectations and address potential symptoms. Option A is incorrect as testicular cancer risk typically decreases with age. Option B may be a concern but is not the primary focus of education for a routine physical exam. Option D (PSA testing) is more relevant for prostate health, which is not the main focus of education for a 51-year-old man's annual physical exam.
The pregnancy period is:
- A. 120 days;
- B. nine weeks;
- C. 280 weeks;
- D. 280 days;
Correct Answer: D
Rationale: The correct answer is D: 280 days. The pregnancy period, also known as gestation, typically lasts around 280 days from the first day of the last menstrual period to the birth of the baby. This duration is calculated based on the average length of a full-term pregnancy, which is approximately 40 weeks. It is important to note that individual pregnancies may vary slightly in duration, but the standard reference is 280 days.
Explanation of other choices:
A: 120 days - This is too short for a full-term pregnancy.
B: Nine weeks - This is only around 63 days, which is far less than the average gestation period.
C: 280 weeks - This is equivalent to around 1960 days, which is much longer than a typical pregnancy duration.
Seven days after ovulation, pituitary secretion of luteinizing hormone (LH) decreases rapidly. What is the cause of this decrease in secretion?
- A. The anterior pituitary gland becomes unresponsive to the stimulatory effect of gonadotropin-releasing hormone (GnRH)
- B. Estrogen from the developing follicles exerts a feedback inhibition on the hypothalamus
- C. The rise in body temperature inhibits hypothalamic release of GnRH
- D. Secretion of estrogen and progesterone by the corpus luteum suppresses hypothalamic secretion of GnRH and pituitary secretion of LH
Correct Answer: D
Rationale: Step 1: After ovulation, the follicle transforms into the corpus luteum.
Step 2: The corpus luteum secretes estrogen and progesterone.
Step 3: Estrogen and progesterone exert negative feedback on the hypothalamus.
Step 4: This inhibits the secretion of GnRH from the hypothalamus.
Step 5: Decreased GnRH leads to reduced LH secretion from the pituitary.
Therefore, the correct answer is D because the secretion of estrogen and progesterone by the corpus luteum suppresses the hypothalamic secretion of GnRH, resulting in decreased pituitary LH secretion.
Summary:
A: Incorrect. The anterior pituitary gland's responsiveness to GnRH is not the cause of the decrease in LH secretion.
B: Incorrect. Estrogen exerts negative feedback on the hypothalamus, not the pituitary.
C: Incorrect. Rise in body temperature does not directly inhibit GnRH secretion