Seminiferous Tubules and Spermatogenesis Quiz
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Questions and Answers

What is the first step in the mechanism of penile erection?

  • Sympathetic impulses contract smooth muscles
  • Parasympathetic neurons release nitric oxide, causing dilation of small arterioles of penis (correct)
  • Penis swells and becomes erect
  • Blood accumulates within the vascular spaces in erectile tissue of penis

    • What is the primary function of FSH in the male reproductive system?

  • Stimulation of spermatogenesis (correct)
  • Inhibition of the release of GnRH
  • Stimulation of the hypothalamus to release GnRH
  • Stimulation of testosterone production

    • Which of the following hormones prevents over secretion of FSH?

  • GnRH
  • Testosterone
  • Inhibin (correct)
  • LH

    • What is the term for the process by which semen is forcefully expelled from the urethra?

    <p>Ejaculation</p> Signup and view all the answers

    What is the name of the hormone that stimulates the release of gonadotropins from the anterior pituitary gland?

    <p>GnRH</p> Signup and view all the answers

    What is the term for the male sex hormones?

    <p>Androgens</p> Signup and view all the answers

    What is the result of the rhythmic contractions in the bulbourethral, prostate, and seminal vesicles?

    <p>Semen moves into the urethra</p> Signup and view all the answers

    What is the name of the hormone that is converted into dihydrotestestrone in some organs?

    <p>Testosterone</p> Signup and view all the answers

    What is the primary function of the seminiferous tubules in each testis?

    <p>To conduct spermatogenesis</p> Signup and view all the answers

    What is the role of interstitial cells in the testis?

    <p>To produce testosterone</p> Signup and view all the answers

    What is the result of meiosis I in spermatogenesis?

    <p>Secondary spermatocytes with 46 unique chromosomes</p> Signup and view all the answers

    What is the final event in spermatogenesis that transforms spermatids into spermatozoa?

    <p>Spermatogenesis</p> Signup and view all the answers

    What is the structure that stores enzymes for breaking down the coatings surrounding the egg?

    <p>Acrosome</p> Signup and view all the answers

    What is the function of the mid piece in a spermatozoa?

    <p>To store mitochondria for energy production</p> Signup and view all the answers

    What happens to the spermatozoa at the end of spermatogenesis?

    <p>They are propelled by cilia in the rete testis</p> Signup and view all the answers

    What is the function of the epididymis in the journey of a sperm?

    <p>To allow spermatozoa to be fully matured and functional</p> Signup and view all the answers

    What stimulates ovulation?

    <p>LH</p> Signup and view all the answers

    What happens to the follicular and thecal cells after ovulation?

    <p>They become corpus luteum cells</p> Signup and view all the answers

    What is the effect of estrogen on the uterine wall?

    <p>It stimulates uterine wall development</p> Signup and view all the answers

    What happens to the corpus luteum if the egg is not fertilized?

    <p>It degenerates and no longer secretes estrogen and progesterone</p> Signup and view all the answers

    What is the effect of progesterone on the uterine lining?

    <p>It stimulates the uterine lining to become more glandular and vascular</p> Signup and view all the answers

    What happens to the uterine lining if the corpus luteum degenerates?

    <p>It disintegrates and sloughs off</p> Signup and view all the answers

    What is the purpose of acrosin enzyme in fertilization?

    <p>It helps the sperm penetrate the inner coating of the ovum</p> Signup and view all the answers

    What happens to the cell membrane of the ovum after fertilization?

    <p>It fuses with the cell membrane of the sperm</p> Signup and view all the answers

    What is the primary function of estrogen in female secondary sex characteristics?

    <p>Development and maintenance of most female secondary sex characteristics</p> Signup and view all the answers

    What triggers the release of FSH from the anterior pituitary gland?

    <p>LHRH released by the hypothalamus</p> Signup and view all the answers

    What is the duration of the ovarian cycle?

    <p>28 days</p> Signup and view all the answers

    What happens on day 14 of the ovarian cycle?

    <p>Ovulation occurs to discharge the ovum</p> Signup and view all the answers

    What is the function of progesterone in the female reproductive system?

    <p>Causing changes in the uterus and mammary glands</p> Signup and view all the answers

    What triggers the development of primary follicles into secondary follicles?

    <p>FSH released by the anterior pituitary gland</p> Signup and view all the answers

    What is the role of the hypothalamus in the ovarian cycle?

    <p>Releasing GnRH to the anterior pituitary gland</p> Signup and view all the answers

    At what age does gonadotropin secretion increase in females?

    <p>10 years of age</p> Signup and view all the answers

    What happens to placental hormonal concentrations after childbirth?

    <p>They decline, allowing prolactin to stimulate milk production</p> Signup and view all the answers

    Which hormone is released from the anterior pituitary gland in response to mechanical stimulation of the breasts?

    <p>Oxytocin</p> Signup and view all the answers

    What is the purpose of birth control?

    <p>To regulate conception voluntarily</p> Signup and view all the answers

    What is the success rate of vasectomy as a contraceptive method?

    <p>99%</p> Signup and view all the answers

    How do intrauterine devices (IUDs) prevent fertilization?

    <p>By forming leukocytes and antibodies in the reproductive tract</p> Signup and view all the answers

    What is the purpose of condoms in contraception?

    <p>To prevent the transmission of STDs and sperm</p> Signup and view all the answers

    What is the purpose of withdrawal method in contraception?

    <p>To withdraw the penis before ejaculation</p> Signup and view all the answers

    Study Notes

    Seminiferous Tubules

    • There are approximately 1,000 seminiferous tubules in each testis, where spermatogenesis takes place.
    • Between the tubules are interstitial cells (Leydig's cells) that produce testosterone.
    • Inside the tubules are Sertoli's cells that support and nourish the sperm.

    Spermatogenesis

    • Spermatogonia (containing 46 chromosomes) undergo DNA replication and produce primary spermatocytes (with 46 pairs of chromosomes).
    • Primary spermatocytes undergo "crossing-over" and meiosis I, resulting in secondary spermatocytes (each containing 46 unique chromosomes).
    • Secondary spermatocytes undergo meiosis II, producing spermatids (with 23 unique chromosomes).
    • Spermatids transform into spermatozoa (containing 23 unique chromosomes) in a final event called spermiogenesis.

    Spermatozoa Structure and Function

    • Each spermatozoon consists of a head (containing 23 chromosomes), a mid-piece (storing mitochondria for energy production), and a tail.
    • The head is enclosed by a structure called an acrosome, which stores enzymes called acrosin for breaking down the coatings surrounding the egg.

    Journey of a Sperm

    • At the end of spermatogenesis, spermatozoa are propelled by cilia in the inner walls of rete testis toward the epididymis.
    • Inside the epididymis, certain enzymatic reactions occur, allowing spermatozoa to mature and become functional but not yet able to fertilize the egg.

    Fertilization

    • Spermatozoa travel from the vagina, through the cervix, into the uterus and uterine tube, and eventually reach the outer coatings of the ovum.
    • The acrosome on the head of spermatozoa is worn off, releasing acrosin enzyme, allowing some sperm to reach the inner coating called zone pellucida.
    • One of the sperm fuses with the ovum, causing rapid electrical depolarization at the cell membrane of the ovum, preventing other sperm from entering.

    Mechanism of Penile Erection

    • Sexual stimulation leads to parasympathetic neurons releasing nitric oxide, causing dilation of small arterioles of the penis.
    • Blood accumulates within the vascular spaces in erectile tissue of the penis, causing it to swell and become erect.

    Mechanism of Emission and Ejaculation

    • Intense sexual stimulation leads to sympathetic impulses, causing:
      • Peristaltic contractions in the testicular ducts, epididymis, vas deferens, and ejaculatory ducts.
      • Rhythmic contractions in the bulbourethral, prostate, and seminal vesicles.
      • Rhythmic contractions in the erectile columns of the penis.
    • Emission: semen moves into the urethra.
    • Ejaculation: semen is forcefully expelled from the urethra.

    Hormonal Control of Male Reproductive Function

    • Hypothalamic and pituitary hormones regulate male reproductive function:
      • GnRH (Gonadotropin-Releasing Hormone) stimulates the anterior pituitary gland to release gonadotropins (FSH and LH).
      • FSH stimulates spermatogenesis.
      • LH (ICSH) stimulates the interstitial cells to produce testosterone.
      • Inhibin prevents over-secretion of FSH.

    Brain-Testicular Axis

    • The hypothalamus releases GnRH, which stimulates the anterior pituitary gland to release gonadotropins (FSH and LH).
    • FSH stimulates spermatogenesis, and LH stimulates the interstitial cells to produce testosterone.

    Male Sex Hormones

    • Testosterone is converted into dihydrotestosterone in some organs, stimulating cells in these organs.

    Hormonal Control of Female Secondary Sex Characteristics

    • Hypothalamic and pituitary hormones regulate female reproductive function:
      • GnRH stimulates the anterior pituitary gland to release gonadotropins (FSH and LH).
      • FSH stimulates the maturation of a follicle.
      • Granulose cells of the follicle produce and secrete estrogen.
      • Estrogen is responsible for the development and maintenance of most female secondary sex characteristics.

    Ovarian Cycle

    • A series of events in the ovarian cortex produce a mature ovum and sex hormones.
    • The cycle lasts about 28 days:
      1. Hypothalamus secretes LHRH, which stimulates the anterior pituitary gland to release FSH.
      2. About 20-25 primary follicles develop into secondary follicles.
      3. The anterior pituitary gland releases a surge of LH, which stimulates ovulation.
      4. Follicular and thecal cells become corpus luteum cells, which secrete estrogen and progesterone.
      5. Estrogen and progesterone stimulate uterine wall development and inhibit secretion of FSH and LH.
      6. If the egg is not fertilized, the corpus luteum degenerates, and the uterine lining disintegrates, producing a menstrual flow.

    Menstrual Cycle

    • The menstrual cycle is regulated by hormonal changes:
      1. The hypothalamus releases GnRH, which stimulates the anterior pituitary gland to release FSH and LH.
      2. FSH stimulates the maturation of a follicle, and LH stimulates ovulation.
      3. Estrogen and progesterone stimulate uterine wall development and inhibit secretion of FSH and LH.
      4. If the egg is not fertilized, the corpus luteum degenerates, and the uterine lining disintegrates, producing a menstrual flow.

    Birth Control

    • Birth control is the voluntary regulation of conception.
    • Contraception is any method used to prevent fertilization of the ovum.
    • Common contraceptive methods and their success rates:
      • Abstinence (100%)
      • Vasectomy (99%)
      • Tubule ligation (99%)
      • Birth control pills (98%)
      • Intrauterine devices (IUDS) (95%)
      • Condom (90%)
      • Diaphragm and/or foam (80%)
      • Withdrawal method (or coitus interruptus) (75%)

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    Related Documents

    Reproductive System Chapter 17 PDF

    Description

    This quiz covers the basics of seminiferous tubules and spermatogenesis, including the process of sperm development and the role of specialized cells.

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