Nokea
The hormone testosterone is tubes called seminiferous tubules that produced by the ________ cells of the are found within each ________. testes.
- A. spermatic cord
- B. spermatogonia
- C. testis
- D. oogonia
Correct Answer: B
Rationale: The correct answer is B: spermatogonia. Spermatogonia are the cells within the seminiferous tubules of the testes that give rise to sperm cells. Testosterone is produced by Leydig cells, not spermatogonia. A is incorrect because the spermatic cord does not produce testosterone. C is incorrect as the testis is the overall organ where the seminiferous tubules are located. D is incorrect as oogonia are female germ cells found in the ovaries, not the testes.
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When a male is castrated before puberty, he becomes:
- A. Female
- B. Cretin
- C. Eunuch
- D. Potent
Correct Answer: C
Rationale: The correct answer is C: Eunuch. When a male is castrated before puberty, he becomes a eunuch because castration removes the testes, leading to a lack of testosterone production and loss of male secondary sexual characteristics. This results in a eunuch having a more neutral appearance and lacking the ability to reproduce.
A: Choosing "Female" is incorrect because castration does not change the individual's genetic sex.
B: Selecting "Cretin" is incorrect as cretinism is a condition caused by severe thyroid hormone deficiency, not related to castration.
D: Opting for "Potent" is incorrect as castration leads to the loss of reproductive ability, making the individual infertile.
Spasm of sternocleidomastoid muscle in the neck causes:
- A. Talipes equinovarus
- B. Torticollis
- C. Cleft lip
- D. Kyphosis
Correct Answer: B
Rationale: The correct answer is B: Torticollis. Spasm of the sternocleidomastoid muscle in the neck causes the head to tilt to one side and the chin to rotate to the opposite side, leading to a condition known as torticollis. Talipes equinovarus (A) is a foot deformity, cleft lip (C) is a congenital facial anomaly, and kyphosis (D) is an abnormal curvature of the spine. These conditions are not directly related to the spasm of the sternocleidomastoid muscle in the neck.
Testosterone produces negative feedback to:
- A. the anterior pituitary to turn off follicle stimulating hormone secretion
- B. the anterior pituitary to turn off both luteinizing hormone and follicle stimulating hormone secretion
- C. Sertoli cells turn off inhibin secretion
- D. the anterior pituitary to turn off luteinizing hormone secretion
Correct Answer: D
Rationale: Step-by-step rationale:
1. Testosterone inhibits the release of luteinizing hormone (LH) through negative feedback.
2. LH is produced by the anterior pituitary.
3. Therefore, testosterone exerts negative feedback on the anterior pituitary to turn off LH secretion.
4. This maintains hormonal balance in the body.
Summary of other choices:
A. Incorrect because testosterone primarily affects LH secretion, not follicle stimulating hormone (FSH).
B. Incorrect as it inaccurately suggests that testosterone turns off both LH and FSH secretion.
C. Incorrect because Sertoli cells are involved in spermatogenesis, not LH regulation.
Testosterone is secreted by
- A. Leydig cells.
- B. Sertoli cells.
- C. spermatocytes.
- D. early spermatids.
Correct Answer: A
Rationale: Testosterone is secreted by Leydig cells in the testes. Leydig cells are interstitial cells located between the seminiferous tubules. They are responsible for producing and secreting testosterone, which plays a crucial role in stimulating the development of male secondary sexual characteristics and maintaining male reproductive functions. Sertoli cells provide nourishment and support for developing sperm cells but do not secrete testosterone. Spermatocytes and early spermatids are involved in the process of spermatogenesis and do not secrete testosterone. Therefore, the correct answer is A because Leydig cells are specifically known for their role in testosterone production.
When do the testes begin to descend?
- A. at birth
- B. two months after birth
- C. two months prior to birth
- D. in the fifth month of pregnancy
Correct Answer: D
Rationale: The correct answer is D: in the fifth month of pregnancy. The testes begin to descend from the abdomen into the scrotum during the fifth month of pregnancy. This process is crucial for proper development and function of the testes. Descending at this stage allows for the testes to be positioned outside the body, which is essential for sperm production as it requires a slightly lower temperature than the internal body temperature.
Summary:
A: at birth - Incorrect, as the descent of the testes occurs during fetal development, not at birth.
B: two months after birth - Incorrect, as the descent happens during pregnancy, not after birth.
C: two months prior to birth - Incorrect, as the descent occurs during pregnancy, not prior to birth.