The Female Reproductive System

The Female Reproductive System

Functions of the Female Reproductive System

  • The Female Reproductive System comprises both external and internal structures.

    • Key Functions:

      • Create egg cells (ova)

      • Provide a site for fertilization

      • Produce and secrete female sex hormones

      • Provide an environment for the developing fetus throughout gestation

Overview of the Reproductive System

  • The reproductive system is essential for producing human offspring, comprising different structures and roles in both male and female bodies.

  • It includes necessary anatomical tissues required for sexual reproduction.

External Female Reproductive System Structures

  • Commonly referred to as the vulva, which consists of:

    • Mons Pubis:

      • Fatty tissue covering the pubic bone.

    • Pudendal Cleft:

      • Crevice along the labia majora housing other structures of the vulva.

    • Labia Majora:

      • Two folds of skin surrounding the vulva, providing protection.

      • Filled with subcutaneous tissue, smooth muscle, fat, and the termination of the round ligament of the uterus.

      • Covered with pubic hair.

    • Labia Minora:

      • Smaller folds of skin within the pudendal cleft, offering protection and sensitivity.

    • Bartholin’s Glands:

      • Glands near the vaginal opening providing lubrication.

    • Clitoris:

      • A small, sensitive organ located at the top of the labia minora, critical for sexual arousal.

Internal Female Reproductive System Structures

  • Consists of:

    • Vagina

    • Cervix

    • Uterus

    • Fallopian Tubes

    • Ovaries

Vagina

  • An opening responsible for sexual intercourse and childbirth, often referred to as the birth canal.

  • It is a thin-walled tube about 8 to 10 cm long, situated between the bladder and rectum, extending from the cervix to the external body.

  • It provides a passageway for infant delivery and menstrual flow.

  • The distal end has a fold of mucosa called the hymen, which may bleed when ruptured during first sexual intercourse, sports activity, tampon insertion, or pelvic examinations.

Cervix

  • The lower, narrow part of the uterus that opens into the vagina.

  • Functions include managing menstruation, allowing sperm entry, protecting the uterus, and significantly remodeling during pregnancy, dilating during labor to assist in childbirth.

Ovaries

  • The primary female reproductive organs, producing eggs (ova) and estrogen.

  • Almond-shaped and size-related to the presence of numerous tiny sac-like structures called ovarian follicles.

  • Each follicle contains a mature egg (oocyte).

  • Eggs are immature and paused in development until puberty, activated by hormones during this time.

  • Usually, one egg matures enough to be fertilized each month, while others dissolve during the menstrual cycle.

Fallopian Tubes

  • Also known as uterine tubes, they provide the site for fertilization.

  • Approximately 10 cm long, extending from the ovaries to the superior region of the uterus.

Uterus

  • Located in the pelvis between the urinary bladder and rectum.

  • A hollow organ that receives, retains, and nourishes fertilized eggs.

  • Size and shape of a pear in a woman who has never been pregnant.

  • Increases in size during pregnancy to accommodate the growing fetus.

  • Composed of three layers:

    • Endometrium: Inner layer, thickening during the menstrual cycle and shedding during menstruation.

    • Myometrium: Middle muscular layer.

    • Perimetrium: Outer layer.

  • The endometrial lining sheds about every 28 days based on ovarian hormone levels, a process known as menses (lasting 3-5 days with average blood loss of 50-150 ml).

Ovulation

  • A monthly process where a mature egg is released from the ovary into the fallopian tube.

  • Fertilization possibility is highest during this phase of the menstrual cycle.

  • If interactions between sperm and egg occur, a zygote forms, travels down the fallopian tube, and implants into the uterine lining (endometrium) if conditions are favorable.

Fertilization Process

  • For pregnancy to occur, sperm travels through the vagina, cervix, uterus, and into fallopian tubes to meet an egg.

  • Enzymes released by sperm aid in penetrating the egg's protective cell wall, forming a zygote.

  • Gender determination:

    • Male: XY chromosomes

    • Female: XX chromosomes

Embryonic Development Stages

  • Cleavage: Early stage of embryonic development post fertilization.

  • By Day 7: Blastocyst attaches to the endometrium, embedding itself.

  • By Day 14: Implantation completed, and uterine mucosa grows over the burrowed embryo (the woman may expect the onset of menses).

Fetal Growth and Development

  • 4 Weeks: The embryo measures 4-6 mm; the brain begins formation, and the heart begins to beat.

  • 8 Weeks: The embryo grows to 8 cm; all body organs developed, the head nearly as large as the body.

  • 9-12 Weeks: Facial feature formation.

  • 18-20 Weeks: Gender identification possible via ultrasound or blood test.

    • Noninvasive prenatal testing: Can determine the presence of Y chromosomes as early as 9-10 weeks.

  • 20 Weeks: Fetus measures 19 cm; heartbeat detectable; mother feels fetal movement (quickening).

    • Lanugo & Vernix: Fine hairs and protective coating that aid in fetal protection and temperature regulation.

  • 24 Weeks: Fetus approximately 23 cm; respiration begins; surfactant (a slippery substance) is present aiding in lung function.

  • 28 Weeks: Development of the central nervous system begins regulation.

  • 36 Weeks: Fetus reaches 35 cm; ear lobes develop.

  • 40 Weeks: Full-term fetus, measuring approximately 40 cm, filling the uterus and receiving antibodies from the mother.

Twins

  • Identical Twins (Monozygotic):

    • Form when one fertilized egg, fertilized by one sperm, splits into two embryos.

    • Both share the same DNA, sex, and physical features.

  • Fraternal Twins (Dizygotic):

    • Occurs when two separate eggs are released simultaneously, each fertilized by different sperm.

    • Have different placentas and amniotic sacs, being genetically distinct.

Trimesters of Pregnancy

  • 1st Trimester (Weeks 1-12): Highest miscarriage risk, symptoms include morning sickness, breast tenderness, and 3-5 lb weight gain.

  • 2nd Trimester (Weeks 13-27): Rapid growth and fetal movement; symptoms include ankle edema, heartburn, and urinary incontinence; 12 lb weight gain.

  • 3rd Trimester (Weeks 28-40): Continued brain and lung development; similar symptoms of the second trimester; 10 lb weight gain, totaling 29-31 lbs.

Stages of Labor

  • Stage 1: Dilation Stage:

    • Lasts 6-12 hours; marked by true contractions until the cervix is fully dilated to 10 cm.

    • Contractions begin weakly, intensifying as the cervix softens and dilates, leading to amniotic fluid release (breaking the water).

  • Stage 2: Expulsion Stage:

    • From full dilation to the birth of the infant; increasing urge to push; baby positioned head first allows unhindered breathing once the skull emerges, followed by the rest of the body.

  • Stage 3: Placental Stage:

    • Delivery of the placenta, typically within 15 minutes post-birth; uterine contractions compress vessels to limit bleeding post-delivery.

Vocabulary of the Female Reproductive System

  • Mons Pubis: Fatty area over the pubic bone developing hair post-puberty, cushioning pelvic region.

  • Pudendal Cleft: Slit between the labia leading to the vaginal opening and urethra.

  • Labia Majora: Outer folds protecting the external reproductive organs.

  • Labia Minora: Smaller inner folds surrounding vaginal and urethral openings, offering protection and sensitivity.

  • Bartholin’s Gland: Produce lubrication fluid for the vagina.

  • Clitoris: Sensitive organ at the top of labia minora, essential for arousal.

  • Cervix: Lower part of uterus that opens into the vagina, dilating during childbirth.

  • Uterus: Muscular organ holding a developing fetus.

  • Fallopian Tubes: Tubes carrying eggs from ovaries to uterus; fertilization usually occurs here.

  • Ovaries: Produce eggs and hormones.

  • Hymen: Membrane covering vaginal opening.

  • Zygote: Result of sperm fertilizing an egg.

  • Cleavage: Rapid division after fertilization.

  • Embryo: Developing baby until 8 weeks after fertilization.

  • Menses: Monthly uterine lining shedding.

  • Quickening: First fetal movement felt by the mother, around 16-20 weeks.

  • Lanugo: Fine hairs on the fetus's body.

  • Vernix: Protective skin coating on the fetus.

  • Surfactant: Helps keep lungs' air sacs open.

  • Amnion: Membrane around the fetus.

  • Amniotic Fluid: Surrounds the fetus during development.

  • Dilation Stage: First labor stage, cervix opens to 10 cm.

  • Expulsion Stage: Baby is born.

  • Placental Stage: Expulsion of the placenta post-birth.