Chapter 25

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Chapter 25
2011-12-15 22:15:29
Reproductive System

Chapter 25
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  1. Name the male and female gametes and gonads.
    • Female: gametes - Secondary oocyte ; gonads - ovaries,
    • Male: gametes - sperm; gonads - testes
  2. Define fertilization
    gentic material from a haploid sprem cell and a haploid secondary oocyte merge into a single diploid nucleus.
  3. Define pregnancy
    Pregnancy is the series of events that occur following fertilization leading to implantation,development of embryo and fetus in the uterus ending usually in 38- 40 weeks.
  4. State the location and function of Leydig cells.
    Legdig cell are located between the seminiferous tubules of the testes. Their function is they produce testosterone.
  5. Defining spermatogenesis
    where the germ cells in males undergo mitosis, then meiosis which results in spermatids. Those spermatids mature into sperm
  6. the events in spermatogenesis
    1) During mitotic division, some stem cell Spermatogonia (2n) migrate away from the basement membrane of a seminiferous tubule, pass through the blood-testis barrier, and differentiate intoPrimary Spermatocytes (2n)2) 1 Primary Spermatocyte (2n) undergoes Meiosis I to become 2 Secondary Spermatocytes(2n, but with two matching chromatids)3) The 2 Secondary Spermatocytes (2n) undergo Meiosis II to become 4 Spermatids (n)4) The 4 Spermatids (n) undergo spermiogenesis to become 4 sperm cells (spermatozoa) after gaining an acrosome, flagellum, and undergoing nucleus elongation)5) Sperm cells are pushed into the lumen of the seminiferous tubule
  7. Defining meiosis and explain why gametes must form by meiosis rather than mitosis
    Meiosis produces gametes with 23 chromosomes ( so in fertilization they fuse to create zygote with 46 chromosomes, the ideal number) while mitosis cannot achieve this.
  8. functions of the sperm cell's head
    contains the nucleus where the 23 chromosomes are
  9. functions of the sperm cell's acrosome
    contains acrosomal enzymes (e.g.hyaluronidase) that helps break the corona radiata surrounding the secondary oocyte for penetration
  10. functions of the sperm cell's Middle piece
    Contain mitochondria----> supplies the energy needed for sperm locomotion and metabolism.
  11. Define puberty and state what marks the onset of puberty:
    • At the onset of puberty, hypothalamus secretes gonadotropin-releasing hormone which stimulates anterior pituitary to secretes luteinizing hormone and follicle stimulating hormone. LH stimulates leydig cells to secret testosterone. And in females, FSH stimulates maturation of primordial follicle into secondary oocyte on montlhy basis.
  12. Describing hormonal control of spermatogenesis including the production site and influence of each hormone
    Gonadotropin-releasing hormone (GnRH) by hypothalamus--> Follicle-stimulating and Luteinizing hormone by Anterior Pituitary glandLH--> Leydig cells release testosterone (required for spermatogenesis)Testosterone--> negative feedback--> suppress LH from Anterior Pituitary gland and GnRH from HypothalamusProstate: Testosterone-->Dihydrotestosterone (DHT)FSH+Testosterone-->Sertoli cells-->Release androgen-binding protein (ABP) that binds testosterone to maintain the levels of testosterone needed for final stages of spermatogenesisWhen adequate levels of sperm cells produced-->Inhibin released by Sertoli cells-->inhibition of FSH
  13. Stating the male secondary sex characteristics
    Muscular and skeletal growth result to wide shoulder and narrow hips, pubis, axillary, facial and chest hair, thickening of the skin, deepening of the voice and increase oil gland secretion.
  14. Defining libido
    sexual desires
  15. Stating testosterone’s influence on libido in both men and women
    it stimulates development of male and female sex drive, reproductive structures and secondary sex characteristics.
  16. Stating in which duct of the testis sperm become mature
    seminiferous tubule
  17. Defining sperm maturation
    when the sperm gains the ability to swim (or accquire motility)
  18. Describing the role of the epididymis and ductus deferens in ejaculation
    Function: Storage of mature sperm for several months and by peristaltic contractions of smooth muscle during sexual arousal help propel sperm along the ducts
  19. Describing the sequence of passageways through which sperm pass from the time they leave the testes until they exit the male body
    sertoli cells-lumen of seminiferous-straigth tubules-ductus epididymis-ductus deferens-ejaculatory ducts-urethra-external urethral.
  20. Describe the vasectomy procedure
    A portion of each ductus deference is removed. An incision is made on either side of the scrotum ducts are located and cut. each is tied in two places with stitches and the portion between the ties is removed. production of sperms still continues in the testes but no longer reach the exterior
  21. Explain how vasectomies can prevent fertilization
    Since the vas deferens are ligated the sperms are unable to exit the persons body to reach an oocyte so prevents fertilization.
  22. State if a vasectomy interferes with testosterone production or libido
    Vasectomy doesn't interfere with testosterone production by Leydig cells,Vasectomy excises a portion of ductus deferens, not Leydig cells, which are found in the interstitial space in the testes. Libido is not effected, since testosterone production still takes place.
  23. Stating the functions of the secretions by each accessory sex gland
    Neutralize acid in the male urethra and female reproductive tract,Provide fructose for ATP production by sperm, Contribute to sperm motility and viability, Help semen coagulate after ejaculation and subsequently break down the clot,Lubricate the lining ofthe urethra and the tip of the penis during sexual intercourse.Glands includes: seminal vesicle, the prostate and the bulbourethral glands.
  24. Describe the physiologic mechanisms that produce erection, ejaculation, and return the penis to its flaccid state.
    • Erection: Erectile tissue found in the corpora cavernosa penis and corpora spongiosum penis, each surrounded by tunica albuginea. Erectile tissue is filled with blood sinuses, smooth muscle and elastic tissue.Erection= the state of enlarged and stiffened penis upon stimulation by the parasympathetic nerves from the sacral part of the spinal cord, this stimulation causes smooth muscle in the walls of arterioles to relax, allowing vessel dilation and large amount of blood surge into the area, in addition the smooth muscle relaxes, widening the blood sinuses
    • Ejaculation: Sexual stimulation-->Sympathetic stimulation of lumbar nerves initiates a reflex, in which the smooth muscles sphincter at the base of urinary bladder closes and a powerful release of semen form the urethra to the exterior takes place.Before ejaculation, peristalsis in epididymis, ductus deferens, seminal vesicles, ejaculatory ducts and prostate propel semen into the penile portion of the urethra.Return to flaccid state: Sexual stimulation ended-->penile arterioles constrict-->penile smooth muscle contracts, decreasing blood sinuses--> Pressure on penile veins is released and blood is drained
  25. Describe oogenesis and follicular development.
    Oogenesis is the formation of gametes in the ovaries. Follicular development in the fetal period matures (Mitosis) to the level of primordial follicle and then pauses development during childhood (Meiosis in progress to form Primary Oocyte). From puberty to Menopause Primordial follicles become Primary follicles (Prophase I) and continue development to become (Meiosis I complete) a Secondary follicle. Mature follicles housing Secondary Oocytes (in metaphase II) lead to ovulation. Meiosis II may complete if fertilization occurs.
  26. State the uterine tissue layer involved in labor and childbirth and the muscle tissue type composing that layer.
    MYOMETRIUM (middle layer)-----> composed of 3 layers of smooth muscle fibers ----> involved in labor and delivery.
  27. State the effect of the acidic environment of the vagina on microbial growth and sperm.
    Acidic environment of vagina inhibits microbial growth and is harmful to sperm ( the alkalinity of semen helps neutralize this acid to increase the viability of the sperm)
  28. State the collective name for the female external genitals and know that the labia majora and labia minora protect the vestibule and aid sexual stimulation.
  29. Describing ovulation
    Ovulation is the ejection of an immature egg (oocyte) from the ovary.
  30. Listing the female secondary sex characteristics
    caused by estrogen: distribution of adipose tissue in the breasts, abdomen, hips, and mons pubis; the voice pitch, the broadness of the pelvis and pattern of hair growth on the body (including underarm, pubic and facial hair)
  31. Stating when ovulation usually occurs in a 28-day ovarian cycle:
    Day 14
  32. Stating the fate of the corpus luteum if the secondary oocyte is not fertilized and if it is fertilized
    if the secondary oocyte is NOT fertilized, the corpus luteum degenerates after 2 weeks into a corpus albicans. If the secondary oocyte is fertilized, the corpus luteum stays active. Levels of progesterone and estrogen depend on whether or not the presence of hCG is around to rescue the corpus luteum (to stimulate its secretory activity).
  33. Define menopause, state its cause, and list common symptoms
    Menopause can be define as the period of a woman's life when prompted by hormonal changes, ovulation and mentration. The cause for menopause is the the decline in estrogen. The symptoms include: hot flashes, tendency for vaginal lubrication to decline after menopause, making intercourse potentially less comfortable, mood swings are common, and increased risk in cardiovascular disease and osteoporosis (free education)
  34. Define sexually transmitted disease and name the developed country where STDs are rising to near-epidemic proportions (the exam will not ask about specific STDs, but do read this important information)
    STDs are diseases that spread through sexual contacts.In the United States,STDs have been rising to near-epidemic proportions; they currently affect more than 65 million people!!!!!!!
  35. Stating the function of the tail of the sperm cell
    Enables motility so it can swim to the secondary oocyte
  36. Describing sperm penetration
    Enzymes on sperm cell heads/strong tail movements help sperm penetrate corona radiata and come in contact with zona pellucida; one glycoprotein in zona pellucida acts as sperm receptor that binds to sperm cell head, triggering acrosomal reaction; acrosomal reaction breaks down plasma membrane of acrosome covering sperm head; acrosomal enzymes released that digest a path through zona pellucida as sperm’s tail pushes it onward; first sperm cell to penetrate entire zona pellucia/reach oocyte’s plasma membrane fuses with oocyte.
  37. Distinguish between fraternal and identical twins
    Fraternal twins result from independent release of two secondary oocyte and subsequence fertelization of each by different spermed they have the same age but genetically dissimilar, Identical twins developed from a single ferterlized Ovum ,have exactly the same genetic material and are always the same sex
  38. Describe ectopic pregnancy
    This occurs when a fertilized egg attaches itself somewhere besides the lining of the uterus.
  39. Define contraception
    prevention of fertilization/impregnation without destroying fertility
  40. Tubal ligation
    Known as having your "tubes tied"; the uterine tubes are either clamped or severed and sealed to prevent the eggs from reaching the uterus for fertilization.
  41. Oral contraceptives
    prevent pregnancy mainly by preventing ovulation though a pill (taken orally) containing progestin/estrogen or progestin alone. Progestin inhibits ovulation by suppressing leutenizing hormone (LH) from the anterior pituitary.
  42. Diaphragm
    a dome-shaped device which is placed over the cervix with s spermicide to prevent conception.
  43. Rhythm Method
    Having unprotected sex only on infertile days of the menstrual cycle. The first seven days and then the 20 day on are considered infertile periods (the pre and postovulatory periods, respectively). Requires knowledge of the length of the woman’s menstrual cycles and the current progression in the cycle.
  44. Defining the embryo
    the stage of development from fertilization to 8 weeks
  45. Describing implantation
    After 6 days of fertilazation the blastocytes loosely attaches to the Endometrium more firmly, endometrial glands in the vicinity enlarge and endometrium became more vascularized.
  46. Defining the amnion
    it is a thin protective membrane which is developed from the epiblast while the amniotic cavity enlarges.
  47. Stating the function of amniotic fluid
    this fluid that fills the amniotic cavity serves as a shock absorber for the fetus, regulates body temperature, prevents drying out of the fetus, and helps prevent injuries to the fetus from surrounding tissues.
  48. Describing the placenta
    Formed from the chorion (fetal) and decidua basalis (mother), serves the purpose for exchange of respiratory gases and nutrients and wastes between the mother and the fetus
  49. Defining the umbilical cord and afterbirth
    the umbilical cord is the connection between the placenta and the embryo(later, the fetus); the afterbirth is the detached placenta from the uterus after pregnancy.
  50. Defining the fetus
    begins at week 9 of development, continues until birth
  51. Human chorionic gonadotropin
    produced by chorion of embryo (roughly 8 days after fertilization); stimuates secretory activity of corpus lutem; hormone detected by home pregnancy tests
  52. Progesterone
    during the first 3-4months of pregnancy progestron and estrogen are secreted by the corpus luteum in the ovary to maintain the lining of uterus during pregnancy and prepare the mammary glands to secrete milk. Estrogens-read above
  53. Relaxin
    produced by the corpus luteum; increases flexibility of the pubic symphysis and dilates the cervix
  54. Define labor, state its other name, and state the influence of oxytocin on labor
    Partuition= process by which the fetus is expelled from the uterus through the vagina.Oxytocin stimulates uterine contractions.
  55. Define lactation
    secretion/ejection of milk by the mammary glands