Chapter 27, Part 2: Female Reproductive System Flashcards
Female Development:
o First 8 to 10 weeks in utero, female cannot be distinguished from male.
o Female reproductive tract develops from the paramesonephric duct (para-meso-nephric).
o Mesonephric duct degenerates… female reproductive organs & genitalia develop instead. All the oogonia (stem cells) a female will ever have are produced within the first 5 months of fetal life.
o At puberty (age 9 – 10 for most girls), there are only 250,000—400,000 primordial ovarian follicles left (still contain primary oocytes).
o Puberty is triggered by changes in the release of GnRH (Gonadotropin Releasing Hormone) from the hypothalamus, changing secretions from the anterior pituitary.
o FSH stimulates the development of several primordial follicles each month, causing them to release estrogen, progesterone, inhibin, and small amounts of androgens (testosterone-like hormones).
Female Oogonia:
o At the end of the 5th fetal month, each ovary contains ~3 million oogonia.
o Some differentiate into primary oocytes shortly before birth.
o These primary oocytes are protected within a primordial ovarian follicle (surrounded by a single layer of follicular cells + basement membrane) and located within the cortex of the 2 ovaries.
Female Puberty:
o Puberty begins at age 9 – 10 years in US, but it is typically a 3 to 4 year process.
o Estrogens released during puberty have widespread effects on the female body:
o THELARCHE = onset of breast development.
o PUBARCHE = appearance of pubic and axillary hair/ glands and sebaceous glands.
o MENARCHE = 1st menses (typically anovulatory 90% of time for first few years).
Age of Menarche:
o 1860: average age of menarche = 16.5 yrs.
o 1997: average age of menarche = 12 yrs.
o Menarche does not occur until a female has reached at least 17% body fat.
o Female adult menstrual cycles usually cease (amenorrhea) if a woman drops below 22% body fat (considered the minimum needed to allow for pregnancy and lactation).
o LEPTIN stimulates gonadotropin secretion (low body fat = low leptin levels = low FSH and LH that drive female menstrual cycle).
Menopause:
o “Climacteric” = change in hormones that accompanies menopause… usually begins when there are less than 1000 primary oocytes left.
o Menopause = permanent cessation of menses (female has gone entire year without a menstrual period).
o Typically occurs age 46 to 54 years (average age in US = 52 years).
o Menstrual periods become erratic and shorter in length.
o With fewer primary oocytes (estimated 3 oocytes by age 50), less estrogen and progesterone are secreted… creates many signs & symptoms:
o Hot flashes; mood swings.
o Headaches; insomnia.
o Hair loss; weight gain.
o Vaginal dryness; loss of bone mass.
o Atrophy of vagina; increase in LDL cholesterol.
o Atrophy of uterus; decrease in HDL cholesterol.
o Increase vaginal infections increase in CVD risk.
Overview of Female Anatomy:
o Internal organs:
o (2) Ovaries.
o (2) Fallopian tubes (oviducts or uterine tubes).
o (1) Uterus.
o (1) Vagina.
o External genitalia (vulva = pudendum)
o Mons pubis = fatty area overlying pubic symphysis).
o Labia majora (singular = labium majus) and encloses labia minora.
o Labia minora (singular = labium minus).
o Vestibule = external openings uretha, vagina, vestibular glands (like bulbourethral glands of male), clitoris.
o Clitoris.
o Vaginal orifice with hymen.
Ovaries:
o Female gonads.
o Function:
o Produce female gametes (ova).
o Secrete hormones (progesterone, estrogens, inhibin, relaxin).
o Gross Anatomy:
o Ovaries are attached to broad ligament via the MESOVARIUM = peritoneal fold containing conduit for blood vessels.
o Ovarian ligament attaches ovary to uterus.
o Suspensory ligament attaches ovary to lateral pelvic wall (also conduit for blood vessels).
Histology of Ovaries:
o Covered by germinal epithelium (simple cuboidal epithelial cells).
o Tunica albuginea just deep to germinal epithelium, surrounding the cortex.
o Ovarian cortex contains most of the primordial and developing follicles
o Medulla of ovary contains larger blood vessels.
o The ovaries do not directly communicate with any other organs leads to release eggs into abdominopelvic cavity.
Oogenesis:
o Birth: 2 million primary oocytes. o Puberty: 250,000--400,000 primary oocytes left within primordial follicles of ovarian cortex. o Each month perhaps 8 to 20 primordial ovarian follicles begin to mature: o Primary ovarian follicles. o Secondary (antral) ovarian follicles. o Graafian follicle —Primary oocyte follicle ruptures & ovum is ovulated, ovum = a Secondary oocyte. o Developing follicles secrete primarily androgens which are converted to estrogen. o Graafian follicle expels egg into abdominopelvic cavity. o Differentiates into a corpus luteum, which cranks up production of both estrogen and progesterone (to prepare the uterus in case the ovum is fertilized). o Corpus luteum also secretes inhibin (from the granulosum which couteracts FSH from the anterior pituitary gland = Negative Feedback. o If no uterine implantation, corpus luteum differentiates into a corpus albicans (scar tissue).
Disorder of Ovaries:
PCOS
o PCOS = polycystic ovary syndrome.
o At least 2 of the following conditions:
o Oligoovulation = infrequent ovulation or anovulation.
o Elevated levels of blood androgens or clinical signs of hyperandrogenism.
o Polycystic ovaries = many small cysts on the ovaries.
o Hyperinsulinism plays a key role (too much insulin increases free testosterone levels in the blood & suppresses atresia (resorption) of the follicles).
o Tend to have elevated LEPTIN levels.
o Most common endocrine disorder of young women in US (5 to 10% of young women = 3.2 – 5.4 million)—most common cause of infertility (hormone levels are screwed up, so no ovulation).
o Hereditary component.
o Infrequent menstrual periods and/or irregular bleeding.
o Infertility because of not ovulating.
o Increased hair growth on the face, chest, stomach, back, thumbs, or toes—a condition called HIRSUTISM—with male-pattern baldness or thinning hair
o Acne, oily skin, or dandruff.
o Weight gain or obesity, usually carrying extra weight around the waist.
o Insulin resistance or type 2 diabetes.
o High cholesterol.
o High blood pressure.
o Patches of thickened and dark brown or black skin on the neck, arms, breasts, or thighs.
o Skin tags, or tiny excess flaps of skin in the armpits or neck area.
o Pelvic pain.
o Anxiety or depression due to appearance and/or infertility.
o Sleep apnea.
Fallopian Tubes:
Uterine Tubes
o 4” long canal that leads directly into uterus, also called the oviduct.
o 4 regions
o Infundibulum.
o Ampulla (where fertilization normally occurs).
o Isthmus.
o Intramural region.
o Fimbriae of the infundibulum guide ovulated ovum into the Fallopian tube.
o Mucosa (cilia to move and reabsorption) + muscularis + serosa.
Disorders of Fallopian Tubes:
o PID = pelvic inflammatory disease:
o Infections from other parts of the reproductive tract (vaginal or uterine STDs) can travel backwards thru Fallopian tubes
o Can cause scarring/fibrosis of tubes, resulting in infertility
o Ectopic pregnancy:
o Implantation of developing embryo is outside the uterus and can be fatal (usually the fallopian tube)
o Increased risk in women smokers
o What moves zygote down the tube? = Cilia and peristaltic contractions of the fallopian tube.
Uterus:
o Size & shape of a pear.
o Located anterior to rectum and posterosuperior to urinary bladder.
o Normally, uterus is ANTEVERTED (tipped slightly anteriorly).
o Supported by 4 sets of ligaments: (like a sling)
o Broad ligaments (peritoneal folds that connects lateral margin of uterus to the wall of the pelvis).
o Round ligaments (binds uterus to anterior body wall).
o Uterosacral ligaments (secures the uterus to the sacrum posteriorly.
o Cardinal ligaments (cervix and superior vagina to lateral walls of pelvis).
o Suspensory ligament anchors ovary to the pelvic wall.
o Ovarian ligament anchors ovary to uterus.
Uterine Prolapse:
o 1st degree: Cervix remains within the vagina.
o 2nd degree: Cervix protrudes thru vaginal orifice to exterior.
o 3rd degree: Entire uterus is outside the vagina.
o Rx: Pelvic exercises, pessary (medical device inserted into vaginal for support), surgery.
Regions of Uterus:
o Fundus. o Body. o Cervix: o Internal cervical os. o Cervical canal. o External cervical os.
