Female Reproductive System Flashcards

Female Reproductive System

• Anatomically similar to the male reproductive system, but physiologically more complex.

Oocytes

• Also referred to as the egg.

• Female gametes or sex cells.

• Functions:

  • Matures and ovulates.

  • Gestation: Period between conception, fertilization, and implantation until birth.

  • Childbirth.

Ovaries

• Female gonads.

• Produce oocytes.

• Produce hormones (e.g., estrogen and progesterone).

• Size: Approximately the size of an almond (3.5 cm long, 2 cm wide).

• Smaller than testes.

• Three layers:

  • Mesovarium:

    • Areolar connective tissue and simple squamous epithelium.

    • Part of the broad ligaments.

  • Ovarian cortex:

    • Where oocytes are made, stored, and mature.

  • Ovarian medulla:

    • Areolar connective tissue.

    • Contains ovarian artery and veins.

Oogenesis

• The process of making and maturing oocytes.

• During fetal development, a female is born with approximately 450,000 oocytes.

• Oocytes are arrested at the primordial follicle stage during fetal development.

• After puberty, some primordial oocytes restart their maturation.

• Oogenesis takes about 230 days.

Oogenesis Timeline

• Day 1: Primordial follicles develop into primary oocytes (12-20).

• Primary oocytes require follicular cells for support and nourishment.

• Follicle: Oocyte with surrounding supportive cells (follicular cells).

• Follicle Stimulating Hormone (FSH) from the anterior pituitary gland stimulates follicle growth and replication, maturing the primary follicle into a secondary follicle.

• Day 150: Primary follicle matures into a secondary follicle.

  • The oocyte grows and is still considered a primary oocyte, but there are more follicular cells.

  • Follicular cells begin to produce estrogen.

• Day 65: Secondary follicle develops an antrum (a small cavity).

  • The antrum fills with fluid, creating pressure responsible for ovulation.

  • Only one antral follicle survives; others undergo atresia. Remaining follicular cells support the surviving antral follicle by producing estrogen and progesterone.

  • If two antral follicles survive it results in fraternal twins.

• Day 10: Primary oocyte becomes a secondary oocyte.

  • Secondary oocyte is more mature in terms of meiosis.

  • The antrum continues to enlarge.

• Graafian Follicle: The follicle with a large antrum.

Ovulation

• Luteinizing hormone (LH) from the anterior pituitary gland stimulates the antrum to fill with more fluid and pressure, leading to the oocyte bursting out (ovulation).

• Oocytes can briefly be in the peritoneal cavity because ovaries are not directly connected to the fallopian tubes.

Monthly Cycle vs. Oogenesis

• Oogenesis takes 230 days, while the female monthly cycle is about 30 days.

• Oogenesis: Process takes ~230 days for ovulation to occur.

• About 28 days after starting the first batch, a second batch of oocytes begins oogenesis. Another batch starts 28 days after that, and so on.

• About 200 oocytes are undergoing development at one given time, with some batches finalizing later to maintain the monthly cycle.

Follicle Stages

• Primordial follicle.

• Primary follicle (transitioning to secondary).

• Secondary follicle (antrum starts to form).

• Antral follicle.

• Graafian follicle (visible to the naked eye as a red blister on the ovary).

• Some women can feel ovulation as a popping sensation.

Corpus Luteum

• After ovulation, follicular cells remaining in the ovary become the corpus luteum (yellow body).

• The corpus luteum produces estrogen and progesterone.

Estrogen and Progesterone

Estrogen

• Functions:

  • Development of secondary sex characteristics:

    • Examples: breast development, sexual dimorphism of the ileum, differences in fat metabolism and storage.

    • Primary sex characteristics: sexual organs, sex chromosomes, major sex hormones.

  • Inhibits follicle-stimulating hormone (FSH) briefly to prevent further oocyte development during possible pregnancy.

  • Regulates the uterine cycle by growing the endometrial layer of the uterus.

Progesterone

• Maintains the endometrial layer of the uterus.

• Estrogen builds the endometrial layer; progesterone maintains it.

Corpus Albicans

• If pregnancy does not occur, the corpus luteum turns into the corpus albicans (white body), which is scar tissue.

• Corpus albicans does not release estrogen and progesterone.

Fallopian Tubes

• After ovulation, oocytes need to enter the fallopian tubes, but there is only a 25% chance of them doing so.

Fimbriae

• Located at the distal ends of the fallopian tubes.

• Functions:

  • Increase the surface area to increase the chance of capturing the oocyte.

  • Create an external current to draw the oocyte into the lumen of the fallopian tubes.

Fallopian Tube Lining

• Lined with pseudostratified columnar epithelium with cilia on the apical surface.

• Cilia move the oocyte (fertilized or unfertilized) towards the uterus.

• Fertilization commonly occurs in the distal third of the fallopian tube.

Potential Issues

• Fallopian tubes are not completely attached to the ovaries, creating a direct connection between the peritoneal cavity and the fallopian tube. Fallopian tubes are open to the uterus, cervix, and vagina, making the female reproductive system open to the entire universe.

Pelvic Inflammatory Disease

• Bacterial infection ascends from the vagina into the peritoneal cavity.

• Causes abdominal pain and can lead to infertility due to scar tissue.

• Female reproductive health is important.

Sperm Cells

• After ejaculation, most sperm cells end up in the peritoneal cavity.

• The female immune system eliminates most sperm cells; only one fertilizes the oocyte.

Ectopic Pregnancy

• Fertilized oocyte implants in an improper place.

Tubal Pregnancy

• The fertilized oocyte implants inside of the fallopian tube.

• Causes immense pain and requires removal of the embryo for the survival of both the mother and fetus.

Peritoneal/Abdominal Pregnancy

• Fertilization and implantation occur in the peritoneal cavity.

• Causes abdominal pain and is fatal for both the mother and the baby.

Tubal Ligation

• Female version of vasectomy, involving cutting and tying off the fallopian tubes.

• More complicated than vasectomy since it requires entry into the peritoneal cavity.

• Often performed during cesarean sections.

• The ends of the fallopian tubes can potentially grow back together, but this is rare (one in a million chance).

Uterus

• Muscular organ responsible for expelling the baby during childbirth.

• Layers:

  • Perimetrium:

    • Outermost layer.

    • Made up of simple squamous epithelium and areolar connective tissue.

  • Myometrium:

    • Middle layer.

    • Made up of smooth muscle.

    • Contracts during childbirth.

  • Endometrium:

    • Inner layer with two sublayers:

      • Stratum basalis:

        • Made up of areolar connective tissue.

        • Replicates cells to replenish the stratum functionalis.

        • The thickness and the number of cells in the stratum basal cell remain the same

      • Stratum functionalis:

        • Grows in response to hormones.

        • Composed of various tissue types including simple squamous, simple columnar, and non-keratinized stratified squamous epithelium.

        • Contains blood vessels and glands.

        • Layer that grows and sheds on a monthly basis.

Uterus Regions

• Fundus: Uppermost region.

• Body: Main portion of the uterus.

• Cervix: Connects the uterus to the vagina.

Ovarian and Uterine Cycle Physiology

• Day 1: Menstruation

  • Shedding of the stratum functionalis from the endometrium.

  • Occurs due to low levels of estrogen and progesterone from the corpus albicans.

  • Blood vessels and glands shut down, and the stratum functionalis sheds away.

  • Lasts for about five days.

• Week after menstruation:

  • Estrogen levels begin to rise as the graphene follicle and supportive follicular cells produce estrogen.

  • Estrogen signals cells in the stratum basalis to replicate and grow, pushing cells into the stratum functionalis, causing it to grow.

• Approaching ovulation:

  • Luteinizing hormone (LH) spikes, leading to ovulation.

• Post-ovulation:

  • Follicular cells left behind become the corpus luteum.

  • Estrogen and progesterone levels rise.

    • Estrogen builds cells.

    • Progesterone maintains cells.

    • The stratum functionalis develops and grows thicker.

• If pregnancy does not occur:

  • The corpus luteum turns into the corpus albicans.

  • Estrogen and progesterone levels fall.

    • Without these hormones, cells are not made or maintained.

    • Menstruation begins again.

• Cycle variations: Ovulation does not have to occur on day 14; it can vary.

• Sexual intercourse increases the chances of ovulation.

• The pheromones affect the female cycle.

Hormone Birth Control

• Progestin (synthetic progesterone) maintains the endometrial cell layers, preventing shedding and menstruation.

• Medications typically include a placebo to allow for menstruation.

• Continuous release of progestin (e.g., through implants or patches) may prevent menstruation.

Uterine Fibroids

• Lumps of dense irregular connective tissue in the uterus.

• More common in older women.

• Can cause pain, especially during menstruation.

• Hysterectomy (complete removal of the uterus) is commonly performed to resolve fibroids, especially in women who are not interested in having more children, that are older.

Endometriosis

• Disorder where cells capable of rapidly dividing, in reponse to Estrogen and Progesterone, are found outside of the uterus.

• Endometrial cells implant in places where they don't belong.

• These cells react to hormone fluctuations, causing growth and pain.

• Cells die when estrogen and progesterone levels fall, causing more pain.

• In severe cases, endometrial cells can implant on the diaphragm, causing pain during breathing during menstruation.

• Endometrial cells can also implant on the parietal pleura, leading to lung collapse during menstruation.

• Hormone treatments can stabilize hormone levels to reduce pain by preventing rapid cell growth and death.

Uterine and Cervical Cancers

Uterine Cancer

• Second most common cancer in women after breast cancer.

• Caused by rapid cell division.

• Mutation allows cells to replicate without estrogen signals.

• 30,000 deaths worldwide per year.

Cervical Cancer

• Caused by the Human Papilloma Virus (HPV).

• HPV triggers proliferation and metastasis of cells in the cervix.

• Pap smears involve scraping cells from the cervix to check for abnormalities.

• HPV vaccine is available.

• HPV can also cause penis cancer in men.

Vagina

• Muscular tube about 9 cm (4 inches) long.

• Mucosa: Non-keratinized stratified squamous epithelium with rugae (folds).

• Rugae:

  • Stimulate the male reproductive organs during intercourse.

  • Allow for stretching during intercourse or childbirth.

• Few mucosal glands; secretions create an acidic environment to kill foreign invaders (e.g., bacteria).

• Acidic environment prevents infections that could lead to pelvic inflammatory disease.

Hymen

• Extension of the non-keratinized stratified squamous epithelium from the vagina.

• Varies greatly in size and shape from person to person.

• Can cover the external orifice of the vagina, blocking menses and vaginal discharge.

• Surgical removal may be necessary.

Vulva

• External genitalia of the female reproductive system.

Labia Majora

• Outer lips, equivalent to the male scrotum.

• Derived from the same embryonic structure.

• Attachment for the round ligament, which is the female equivalent of the gubernaculum.

Labia Minora

• Inner lips.

• Do not have hair.

• Composed of erectile tissue corresponding to the male corpora cavernosa.

Clitoris

• The tiny, button-like structure is also known as the glans clitoris.

• The female equivalent of the glans penis in men.

• Very sensitive area associated with orgasms and covered in prepuce (foreskin).

Vestibule

• Area between the labia minora.

• Contains:

  • Vestibular glands: Equivalent to the bulbourethral glands, producing mucus for preparation of sexual intercourse.

  • External urethral orifice: Opening to the urethra.

  • External vaginal orifice: Opening to the vagina.

Pelvic Floor Muscles

• Hold organs in place.

• Can weaken due to age or multiple childbirths.

Muscles

• Bulbospongiosus:

  • Constricts the vaginal organs in females.

• Levator ani:

  • Elevates the sigmoid colon during defecation.

• External anal sphincter:

  • Controls defecation.

• Urogenital diaphragm:

  • Triangular muscle group.

  • Forms the external urethral sphincter.

  • Contains a central tendon that can tear during childbirth.

Episiotomy

• Incision of the vaginal orifice to prevent tearing of the central tendon of the perineum during childbirth.

• Cuts the bulbospongiosus muscle and part of the urogenital diaphragm.

• Can lead to urinary incontinence.

Kegel Exercises

• Strengthen pelvic floor muscles.

• Can help improve healing after episiotomy.

Prolapsed Uterus

• The uterus falls out of the vaginal orifice due to weak pelvic muscles.

• Common in older women or women who have given multiple births.

• Treatment involves pushing the uterus back in place and using padding to prevent further prolapse.

• Hysterectomy can be performed if the woman does not want to have more children.