Reproductive System rev 5-11

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Reproductive System rev 5-11

• The term genitalia refers to male and female
  reproductive organs.
• Male Reproductive System Anatomy
• The scrotal sac contains 2 testes.
• The process of sperm formation is called
  spermatogenesis.

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• The testes are located outside of the body
  because sperm need lower temperatures to survive.
• Sperm production takes place in the seminiferous
  tubules of the testes
• In between the seminiferous tubules are
  interstitial cells which produce testosterone,
  the male hormone.
• Many seminiferous tubules join to become the
  epididymus. Sperm are stored here and maturation
  also occurs.

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• Sperm enter the vas deferens or ductus deferens
  which passes through an opening in the wall of
  the body called the inguinal canal.
• The ability of newly formed sperm to swim
  develops in the epididymis and the vas deferens.
• Sperm continue their maturation here.
• A vasectomy ties off the vas deferens so sperm
  are no longer available for fertilization.

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• The vas deferens connects to the ejaculatory duct
  after it merges with the seminal vesicle duct.
• When the male ejaculates semen, rhythmic
  contractions of smooth muscle propel the sperm
  through the ejaculatory duct and then through the
  urethra.
• The penis is the male organ of sexual
  intercourse. It contains erectile tissue that
  fills with blood and causes the erection during
  sexual stimulation.

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• Glands which help sperm survive
• Seminal vesicles produce seminal fluid which is a
  watery mixture containing fructose, which
  provides energy for the sperm, and prostaglandins
  which are thought to induce muscle contractions.
• Prostate glandproduces an alkaline fluid which
  raises the pH of the vagina to a more optimal pH.
  
• Cowpers or bulbourethral glands secrete mucus
  into the urethra during sexual arousal. This
  provides lubrication for intercourse and washes
  away traces of acidic urine

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Sperm Production

• Meiosis
• Purpose produces sperm and eggs with half the
  number of chromosomes (23) of somatic cells.
  (Cells with ½ the chromosomes are called haploid
  cells.)
• Sperm formation and maturation takes about 9-10
  weeks. Sertoli cells surround and nourish the
  growing sperm cells.
• Egg maturation and release takes about 14 days
  and occurs once per month

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• Cell division terminology
• Gamete sperm or egg produced by meiosis
• Diploid describes the normal number of
  chromosomes in any cell
• Haploid cell which contain 23 chromosomes

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• Sperm
• consist of 3 major parts a head, midpiece, and a
  tail.
• The head contains the nucleus and 1/2 of the
  chromosome number of the parent.
• Acrosome covers the head.
• The midpiece contains mitochondria and ATP.
• The tail propels the sperm.

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Regulation of Male Reproductive Activity

• Hormones
• Testosterone
• Source Leydig cells in seminiferous tubules
• Function controls growth and function of male
  reproductive tissues, stimulates aggression and
  sexual behavior, and secondary sexual
  characteristics
• GnRH Gonadotropin-releasing hormone from the
  hypothalamus stimulates the anterior pituitary
  gland to release LH and FSH
• LH stimulates production of testosterone
• FSH (Follicle Stimulating Hormone) may enhance
  sperm formation

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The Female Reproductive System

• Anatomy
• The external female genitalia or vulva
• the Mons Pubis, a fatty, rounded tissue area,
  covers the pubic symphysis.
• The Labia Majora are 2 elongated, pigmented, hair
  covered, fat padded skin folds which surround and
  enclose the Labia Minora.

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• The Labia Minora are 2 smaller, highly vascular,
  hair free folds.
• The Clitoris is a small organ partly enclosed by
  the labia minora.
• The Urethral opening lies between the clitoris
  and the vaginal opening.

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• Internal female reproductive organs
• Ovaries are the primary reproductive organs.
  They lie near the ends of the fallopian tubes
  (also called oviducts).
• The ovaries produce eggs called oocytes. Eggs
  have 1/2 the number of chromosomes as the parent.

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• They also produce the hormones estrogen and
  progesterone
• The distal ends of the fallopian tubes are funnel
  shaped and have fingerlike projections called
  fimbriae.
• The egg is propelled toward the uterus by the
  cilia on the walls of the fallopian tubes.
• If fertilization by a sperm occurs, it usually
  takes place in the distal third of the fallopian
  tube.

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• The uterus is a hollow, pear shaped, muscular
  organ which is located between the bladder and
  the rectum. It will incubate the fertilized
  egg.
• Its narrow, lower end is called the cervix. The
  middle part of the uterus is called the body and
  the upper part is called the fundus.

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• Uterine layers
• Endometrium inner layer
• A fertilized egg will implant into this layer.
  After implantation, the endometrium helps form
  the placenta.
• This is the layer that sloughs off during
  menstrual flow.
• Myometrium middle, muscular layer
• Perimetrium outer layer
• Cervix the narrow opening in the lower part of
  the uterus

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• The cervix joins the vagina.
• It serves as a birth canal and the female organ
  for sexual intercourse.
• It permits the passage of menstrual blood to the
  outside of the body.
• Vestibular glands secrete lubricating mucus.

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• The Breasts are considered to be part of the
  reproductive organs
• are really modified sweat glands which produce
  milk to nourish newborn infants.
• milk production (lactation) is stimulated by
  estrogen and progesterone only when birth has
  actually occurred.
• the nipple is at the center of each breast. It
  contains smooth muscles that can contract and
  cause the nipple to become erect.

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• Surrounding the nipple is the pigmented areola.
• Internally, the breasts contain mammary glands
  that produce milk.
• The glands consist of many milk producing
  lobules. Contractile cells around each lobule
  allow the milk to be released and ducts deliver
  the milk to the nipple.

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Menstrual Cycle

• Each month the ovaries and uterus go through a
  pattern of changes called the menstrual cycle.
• Typically lasts 28 days is controlled by
  hormones
• Menstrual cycles begin at puberty and end at
  menopause
• A complete menstrual cycle consists of 2 linked
  cycles an ovarian and a uterine cycle
• Ovarian cycle oocytes mature and are released
• Immature follicle develops GnRH, FSH and LH
  increase

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• Estrogen and progesterone secreted
• Follicle matures now called Graafian follicle
• Increasing estrogen causes surge of LH so that
  ovulation occursthe egg is released
• A corpus luteum forms from the ruptured follicle
  site and secretes large amounts of estrogen and
  progesterone to prepare the endometrium for the
  possible pregnancy
• If no pregnancy occurs, estrogen and progesterone
  levels decline and another menstrual cycle
  begins.

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• If the egg is fertilized, it moves down the
  fallopian tube and implants in the uterine
  endometrium
• The developing embryo secretes its own hormones
  to enable the corpus luteum to continue to
  secrete estrogen and progesterone until the
  placenta develops.
• The placenta will take over the job of secreting
  progesterone and estrogen as well as become a
  nutrient/waste filter between the maternal and
  fetal circulation.

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• Uterine cycle prepares uterus for pregnancy
• Menstrual phase With no pregnancy, days 15,
  estrogen and progesterone decrease, endometrial
  lining degenerates, menstruation occurs
• Proliferative phase days 614, estrogen and
  progesterone increase, endometrial lining begins
  to proliferate
• Ovulation day 14

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• Secretory phase corpus luteum produces
  progesterone and estrogen, endometrium continues
  to proliferate, uterine glands mature and produce
  glycogen as a potential energy source for an
  embryo

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Maintenance of Menstrual Cycle

• Cycles of hormones of pituitary and reproductive
  structures
• Positive feedback
• In proliferative phase, increasing estrogen
  causes surge in LH
• Negative feedback
• In secretory phase, steady levels of estrogen and
  progesterone inhibit LH and FSH release

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Infertility Inability to Conceive

• Many causes of infertility
• Number and quality of sperm, pelvic inflammatory
  disease (PID), endometriosis
• Enhancing fertility
• Options artificial insemination, in vitro
  fertilization, GIFT and ZIFT,
• fertility-enhancing drugs, surrogate mothers

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Sexually Transmitted Diseases (STDs) Worldwide
Problem

• Bacterial gonorrhea, syphilis, chlamydia
• Viral HIV, hepatitis B, genital herpes, genital
  warts
• Other yeasts (Candida), protozoan (Trichomonas),
  arthropod (pubic lice)
• Prevention
• Strategies choose partner wisely, communicate,
  use suitable barriers, get tested and treated