Nokea
Inhibin is
- A. is secreted by Sertoli cells to inhibit follicle stimulation hormone from the anterior pituitary.
- B. is secreted by the anterior pituitary to inhibit testosterone secretion.
- C. is secreted by Sertoli cells to inhibit testosterone secretion
- D. is secreted Leydig cells to inhibit Sertoli cells
Correct Answer: A
Rationale: Inhibin is secreted by Sertoli cells to inhibit follicle stimulating hormone (FSH) from the anterior pituitary. This is the correct answer because inhibin acts as a negative feedback mechanism to regulate FSH levels in the body. Sertoli cells are specifically involved in spermatogenesis and play a crucial role in regulating FSH secretion through inhibin. Choices B, C, and D are incorrect because inhibin does not inhibit testosterone secretion or act on Leydig cells. It specifically targets FSH secretion to regulate the process of spermatogenesis.
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A female athlete who took testosterone-like steroids for several months stopped having normal menstrual cycles. What is the best explanation for this observation?
- A. Testosterone stimulates inhibin production from the corpus luteum
- B. Testosterone binds to receptors in the endometrium, resulting in the endometrium’s failure to develop during the normal cycle
- C. Testosterone binds to receptors in the anterior pituitary that stimulate the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- D. Testosterone inhibits the hypothalamic secretion of gonadotropin-releasing hormone and the pituitary secretion of LH and FSH
Correct Answer: D
Rationale: The correct answer is D because testosterone inhibits the hypothalamic secretion of gonadotropin-releasing hormone (GnRH) and the pituitary secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This disruption in the normal hormonal feedback loop leads to the suppression of ovulation and the menstrual cycle. Option A is incorrect because inhibin is not directly affected by testosterone. Option B is incorrect as testosterone does not bind to endometrial receptors directly. Option C is incorrect because testosterone does not stimulate the secretion of FSH and LH from the anterior pituitary.
The transmission of sound vibrations through the inner ear occurs chiefly through:
- A. Bone
- B. Nerve fibers
- C. Air
- D. Liquid
Correct Answer: D
Rationale: The correct answer is D: Liquid. Sound vibrations travel through the inner ear mainly through the liquid-filled cochlea. When sound waves reach the ear, they cause the fluid inside the cochlea to move, stimulating hair cells that convert the vibrations into electrical signals sent to the brain. Choice A (Bone) is incorrect as bone conduction bypasses the middle ear, while sound must pass through it to reach the cochlea. Choice B (Nerve fibers) is incorrect because nerves transmit the electrical signals generated by the hair cells, not sound vibrations themselves. Choice C (Air) is incorrect as the inner ear is filled with liquid, not air, and sound waves need a medium like air to travel through the ear canal but not inside the inner ear.
The glands that produce a thick, yellowish secretion which nourishes and activates sperm are the __
- A. bulbo-urethral glands
- B. prostate
- C. seminal glands (vesicles)
- D. ejaculatory duct
Correct Answer: A
Rationale: The correct answer is A: bulbo-urethral glands. These glands produce a thick, yellowish secretion known as pre-ejaculate or Cowper's fluid. It serves to nourish and activate sperm. The other choices are incorrect because:
B: The prostate gland produces a milky fluid that helps with sperm motility.
C: The seminal glands (vesicles) produce a fluid that provides energy for sperm.
D: The ejaculatory duct is a passageway for semen to leave the body, it does not produce any secretions.
Female reproductive system arises from
- A. Paramesonephric (Mullerian) ducts
- B. Mesonephric (Wolffian) ducts
- C. aldosterone
- D. FSH
Correct Answer: A
Rationale: The female reproductive system arises from Paramesonephric (Mullerian) ducts. These ducts develop into the fallopian tubes, uterus, and upper part of the vagina. Initially present in both sexes, in females, they persist and differentiate into the female reproductive organs under the influence of estrogen. Mesonephric (Wolffian) ducts develop into male reproductive structures. Aldosterone is a hormone related to electrolyte balance and has no direct role in female reproductive system development. FSH (Follicle-Stimulating Hormone) is a pituitary hormone that stimulates ovarian follicle development but does not play a role in the initial development of the female reproductive system.
Mrs. Marx, 60, was recently diagnosed as having endometrial cancer. She smokes a pack of cigarettes a week and is about 5 lb over her ideal weight. Which of these factors may be related to her developing endometrial cancer?
- A. Smoking
- B. Infertility
- C. Poverty
- D. Obesity
Correct Answer: D
Rationale: Obesity is a known risk factor for endometrial cancer due to increased estrogen levels.