Reproductive - Physiology Flashcards

1
Q

Estrogen

  • Source
  • Functions
A
  • Source
    • Ovary (17β-estradiol), placenta (estriol), adipose tissue (estrone via aromatization)
    • Potency: estradiol > estrone > estriol
  • Functions
    • Development of genitalia and breast, female fat distribution
    • Growth of follicle, endometrial proliferation, increased myometrial excitability
    • Upregulation of estrogen, LH, and progesterone receptors
      • Feedback inhibition of FSH and LH, then LH surge
      • Stimulation of prolactin secretion
    • Increased transport proteins, SHBG; increased HDL; decreased LDL
    • Pregnancy:
      • 50-fold increase in estradiol and estrone
      • 1000-fold increase in estriol (indicator of fetal well-being)
    • Estrogen receptors expressed in the cytoplasm
      • Translocate to the nucleus when bound by ligand
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2
Q

Progesterone

  • Source
  • Functions
  • Decreased vs. increased progesterone
A
  • Source
    • Corpus luteum, placenta, adrenal cortex, testes
  • Functions
    • Stimulation of endometrial glandular secretions and spiral artery development
    • Maintenance of pregnancy
    • Decreased myometrial excitability
    • Production of thick cervical mucus, which inhibits sperm entry into the uterus
    • Increased body temperature
    • Inhibition of gonadotropins (LH, FSH)
    • Uterine smooth muscle relaxation (preventing contractions)
    • Decreased estrogen receptor expressivity
    • Prevents endometrial hyperplasia
  • Decreased vs. increased progesterone
    • Fall in progesterone after delivery disinhibits prolactin –>Ž lactation. 
      • Progesterone is _pro-gest_ation.
      • Prolactin is _pro-lact_ation.
    • Increased progesterone is indicative of ovulation.
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3
Q

Tanner stages of sexual development

  • A Tanner stage
  • I
  • II
  • III
  • IV
  • V
A
  • A Tanner stage is assigned independently to genitalia, pubic hair, and breast
    • e.g., a person can have Tanner stage 2 genitalia, Tanner stage 3 pubic hair
  • I
    • Childhood (prepubertal)
  • II
    • Pubic hair appears (pubarche)
    • Breast buds form (thelarche)
  • III
    • Pubic hair darkens and becomes curly
    • Penis size/length increase
    • Breasts enlarge
  • IV
    • Penis width increases, darker scrotal skin, development of glans
    • Raised areolae
  • V
    • Adult
    • Areolae are no longer raised
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4
Q

Menstrual cycle

  • Phases
    • Follicular
    • Luteal
    • Menstruation
    • Follicular growth
  • Substances
    • Estrogen
    • Progesterone
A
  • Phases
    • Follicular phase can vary in length.
    • Luteal phase is usually a constant 14 days.
    • Ovulation day + 14 days = menstruation.
    • Follicular growth is fastest during 2nd week of proliferative phase.
  • Substances
    • Estrogen stimulates endometrial proliferation.
      • Increased estrogen –> LH surge –> ovulation –> progesterone (from corpus luteum) –> progesterone levels fall –> menstruation (via apoptosis of endometrial cells)
    • Progesterone maintains endometrium to support implantation.
      • Decreased progesterone –>Ž decreased fertility.
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5
Q

Menstrual cycle

  • Oligomenorrhea
  • Polymenorrhea
  • Metrorrhagia
  • Menorrhagia
  • Menometrorrhagia
A
  • Oligomenorrhea
    • > 35-day cycle.
  • Polymenorrhea
    • < 21-day cycle.
  • Metrorrhagia
    • Intermenstrual bleeding
    • Frequent but irregular menstruation.
  • Menorrhagia
    • Heavy menstrual bleeding
    • > 80 mL blood loss or > 7 days of menses.
  • Menometrorrhagia
    • _​_Heavy, irregular menstruation at irregular intervals.
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6
Q

Oogenesis

  • 1° oocytes
  • Meiosis I
  • Meiosis II
  • 2° oocyte
A
  • 1° oocytes begin meiosis I during fetal life and complete meiosis I just prior to ovulation.
  • Meiosis I is arrested in prOphase I for years until Ovulation (1° oocytes).
  • Meiosis II is arrested in metaphase II until fertilization (2° oocytes).
    • An egg met a sperm.
  • If fertilization does not occur within 1 day, the 2° oocyte degenerates.
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7
Q

Ovulation

  • Estrogen
  • Temperature
  • Mittelschmerz
A
  • Estrogen
    • Increased estrogen, increased GnRH receptors on anterior pituitary.
    • Estrogen surge then stimulates LH release Ž–> ovulation (rupture of follicle).
  • Temperature
    • Increased temperature (progesterone induced).
  • Mittelschmerz
    • ​Refers to transient mid-cycle ovulatory pain
    • Classically associated with peritoneal irritation
      • e.g., follicular swelling/rupture, fallopian tube contraction
    • Can mimic appendicitis.
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8
Q

Pregnancy

  • Fertilization
  • Implantation
  • Syncytiotrophoblasts
A
  • Fertilization
    • Most commonly occurs in upper end of fallopian tube (the ampulla).
    • Occurs within 1 day of ovulation.
  • Implantation within the wall of the uterus occurs 6 days after fertilization.
  • Syncytiotrophoblasts secrete hCG, which is detectable in blood 1 week after conception and on home test in urine 2 weeks after conception.
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9
Q

Lactation

  • After labor
    • Progesterone and estrogen
    • Suckling
  • Prolactin
  • Oxytocin
A
  • After labor
    • The decrease in progesterone and estrogen disinhibits lactation.
    • Suckling is required to maintain milk production, since increased nerve stimulation increases oxytocin and prolactin.
  • Prolactin
    • Induces and maintains lactation
    • Decreases reproductive function.
  • Oxytocin
    • Assists in milk letdown
    • Also promotes uterine contractions.
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10
Q

Lactation

  • Breastmilk
  • Breastfeeding
A
  • Breastmilk
    • The ideal nutrition for infants < 6 months old.
    • Contains maternal immunoglobulins (conferring passive immunity; mostly IgA), macrophages, and lymphocytes.
    • Reduces infant infections and is associated with decreased risk for the child to develop asthma, allergies, diabetes mellitus, and obesity.
    • Exclusively breastfed infants require vitamin D supplementation.
  • Breastfeeding 
    • Decreases maternal risk of breast and ovarian cancer
    • Facilitates mother-child bonding.
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11
Q

hCG

  • Source
  • Functions
  • Subunits
  • Pathology
A
  • Source
    • Syncytiotrophoblast of placenta.
  • Functions
    • Maintains the corpus luteum (and thus progesterone) for the 1st trimester by acting like LH (otherwise no luteal cell stimulation, and abortion results).
      • In the 2nd and 3rd trimesters, the placenta synthesizes its own estriol and progesterone and the corpus luteum degenerates.
    • Used to detect pregnancy because it appears early in the urine.
  • Subunits
    • α subunit structurally identical to α subunits of LH, FSH, and TSH.
    • β subunit is unique (pregnancy tests detect β subunit).
  • Pathology
    • hCG is increased in multiple gestations and pathologic states (e.g., hydatidiform mole, choriocarcinoma).
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12
Q

Menopause

  • Definition
  • Age
  • Menopause causes…
A
  • Definition
    • Decreased estrogen production due to age-linked decline in number of ovarian follicles.
    • Usually preceded by 4–5 years of abnormal menstrual cycles.
  • Age
    • Average age at onset is 51 years (earlier in smokers).
    • Menopause before age 40 can indicate premature ovarian failure.
  • Menopause causes HAVOCS
    • Hot flashes
    • Atrophy of the Vagina
    • Osteoporosis
    • Coronary artery disease
    • Sleep disturbances
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13
Q

Menopause

  • Hormones
    • Estrogen
    • FSH
  • Hormonal changes
A
  • Hormones
    • Source of estrogen (estrone) after menopause becomes peripheral conversion of androgens, increased androgens –>Ž hirsutism.
    • Really increased FSH is specific for menopause (loss of negative feedback on FSH due to decreased estrogen).
  • Hormonal changes
    • Decreased estrogen
    • Really increased FSH
    • Increased LH (no surge)
    • Increased GnRH.
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14
Q

Spermatogenesis (572)

  • Timeline
  • Location
  • Produces…
A
  • Timeline
    • Spermatogenesis begins at puberty with spermatogonia.
      • “Gonium” is going to be a sperm
    • Full development takes 2 months.
  • Location
    • Occurs in seminiferous tubules.
  • Produces…
    • Spermatids that undergo spermiogenesis (loss of cytoplasmic contents, gain of acrosomal cap) to form mature spermatozoon.
      • Zoon” is “Zooming” to egg
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15
Q

Androgens

  • Examples
  • Source
A
  • Examples
    • Testosterone, dihydrotestosterone (DHT), androstenedione.
  • Source
    • DHT and testosterone: testis
    • AnDrostenedione: ADrenal
    • Potency: DHT > testosterone > androstenedione.
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16
Q

Androgens:
Functions of testosterone

A
  • ƒƒDifferentiation of epididymis, vas deferens, seminal vesicles (genitalia, except prostate)
  • ƒƒGrowth spurt: penis, seminal vesicles, sperm, muscle, RBCs
  • ƒƒDeepening of voice
  • Closing of epiphyseal plates (via estrogen converted from testosterone)
  • Libido
  • Testosterone is converted to DHT by the enzyme 5α-reductase, which is inhibited by finasteride
  • Exogenous testosterone –>Ž inhibition of hypothalamic–pituitary–gonadal axis –>Ž decreased intratesticular testosterone –>Ž decreased testicular size Ž–> azoospermia.
17
Q

Androgens:
Functions

  • DHT
  • Aromatase
A
  • DHT
    • Early—differentiation of penis, scrotum, prostate
    • Late—prostate growth, balding, sebaceous gland activity
  • Aromatase
    • In the male, androgens are converted to estrogen by cytochrome P-450 aromatase (primarily in adipose tissue and the testis).
    • Aromatase is the key enzyme in the conversion of androgens to estrogen.