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Reproduction > The Menstrual Cycle > Flashcards

The Menstrual Cycle Flashcards

1
Q

What is the endometrium of the uterus?

A

The inner lining of the uterus that is shed every month during the menstrual cycyle
-Glandular tissue, under endoncrine control
- Extensive stroma
- Highly vasculurised networked supploed by spiral arteries
- Distinct histological changes with phases of the m cycle (Noyes criteria)
- Columnar epithelial cell lining (proliferates and degenerates in one cycle)
- Glands extend deep into the endometrial stroma
- Implantation occurs 6-12 days after fertilisation
- Window of implantation - endometrium optimally receptive to blastocyst (36hrs).

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2
Q

What comprises the Upper Female Reproductive Tract (FRT)

A
  • The fallopian tubes
  • ovarian ligament
  • Fimbriae
  • UTERUS
  • Ovary (perimetrium, myometrium and endometrium)
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3
Q

What is the Lower FRT comprised of?

A

The cervix and vagina

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4
Q

What is the female repoductive lifecycle?

A
  • Menarche:
  • first ovarian-controlled uterine bleed
  • Maturation of HPO axis
  • increase in oestrogen (Sexual characteristics)
  • Childbearing years (mestrual cycle)
  • Around 28 day cycle
  • menses, menstruatuion (bleeding phase)
  • Menopause/Climacteric
  • Oestrogen withdrawl, follicle depletion
  • Cessation of menses
  • Size, function of ovaries
  • Mean age 51.4
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5
Q

What is the differnece between the ovarian and uterine cycle?

A
  • Ovarian : interval between successive ovulations
  • describes ovum maturation and release under endocrine regulation
  • Progression of follicle - corpus luteum
  • Uterine cycle:
  • comprises the follicular pase (1-14 days) and the luteal phase (15-28 days)
  • Folliculogenesis
  • Uterine cycle - describes the effects of oestrogen and progesterone on the uterus (endometrium)
  • Has a proliferative and secretory phase
  • Has vascular funcrtion, menses
  • Angiogenesis
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6
Q

What are the main reproductive hormones in the FRT?

A

Oestradiol-17ß
* produced from androstenedione and aromatase in granulosa, CL and adipose
**Progesterone (P4) **
* secreted by corpus luteum
**Follicle Stimulating Hormone (FSH) **
* follicle development and recruitment
**Luteinising Hormone (LH) **
* maturation of dominant follicle, ovulation, maintenance of the CL
**Inhibins **
* produced by ovarian granulosa cells to inhibit FSH secretion; Inhibin A during luteal
phase; Inhibin B in follicular phase
Anti-Mullerian Hormone (AMH)
* marker of ovarian reserve

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7
Q

What is the action of oestrogen (c18 steroid)?

A
  • Widespread effects on reproductive, musculoskeleta,vascular and cns
  • Regulate GnRH secretion
  • stimulate proliferation of endometrium
  • Prepares endomentrium for progesterone action
  • -Stimulate sex characteristics of female
  • Stimulates ductal growth of breast tissue.
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8
Q

What is the action of Progesterone (c21 steroid)?

A
  • Pro gestation - hormone of pregnancy
  • Regulate GnRH secretion
  • Prepare endometrium for implantation
  • Stimulate decidualisation of the endometrium
  • Maintain the uterus during pregnancy
  • Stimulate growth (alveolar) of breast tissue
  • Synergistic and opposing effects to oestrogen
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9
Q

What is the idealised menstrual cycle?

A
  • Day 1-7 bleeding
  • Proliferative (Follicular) - when bleeding is more or less over - endometrium begins to regenerate
  • Day 12-14 Ovulation
  • Secretory (Luteal) phase (!4-28)
  • Implantation- this cycle stops if pregnancy occurs
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10
Q

What is dysmenorrhoea?

A
  • painful periods
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11
Q

What are the proliferative and secretory phase dominated by?

A

Proliferative - oestrogen - dominated
- variable duration typically 14 days
Secretory - progesterone dominated

Important so that women know when they are most fertile

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12
Q

Why do FSH and LH begin to increase at the start of the menstrual cycle?

A
  • act on the follicles of the ovary which secrete eostrogen
  • these promote endometrial proliferation
  • Around Day 14 - there is a LH peak which is needed for oestrogen levels to rise prior to ovulation = positive feedback regulation
  • After ovulation LH levels decrease rapidly
  • Progesterone levels increase so that endometrium can thicken so that a blastocyst can embed (prepares endometrium for implantation)
  • If no implantation, progesterone levels, and oestrogen levels fall off and LH and FSH levels begin to rise again
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13
Q

What process do inhibins inhibit in the menstrual cycle?

A
  • The recruitment of follicles
  • Once there are enough follicles the growth of other follicles are supressed
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14
Q

stalks

What are pinopodes?

A
  • Markers of endometrial receptivity that grow on the endometrial cell layer
  • Attract the blastocyst to them
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15
Q

What is the difference between proliferative and secretory ohase endometrium?

A
  • Prolferative : round,regular. Stroma- supprt,nutrients
  • Secretory - tortuous,twisted glands .Glycogen droplets prepares for conception - first nutrition for embryo
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16
Q

What supplies the endometrial vascular supply?

A
  • The uterine artery and vein
17
Q

What layer of the endometrium sheds?

A
  • The functional layer of the endometrium
18
Q

What is the vascular aspect of the endometrium?

A
  • Rapid angiogenesis and spinal artery lengthening in ptoliferative phase
  • Endometrial regression, spinal arteru coiling causes resistance to blood flow resulting in endometrial hypoxia followed by tissue degeneration
  • Matrix metalloproteinases (MMP-8-9) from endometrial stroma and proteases from invading leukocytes during late secretory phase begin matrix degradation
  • Mechanism : Progesterone withdrawl increases expression of COX 2 and increased prostaglandin (PGF2a) production by endometrial stromal cells and increased prostaglandin-receptor density on blood vessels = vasoconstriction
  • (primary symenorrhea caused by PGCS inducinf myometrial contractions and ischaemia)
  • Matrix metalloproteinases (MMPs) from endometrial stroma and proteases from invading leukpcytes during late secretory phase begin matix degradation and recovery
  • Mestrual blood consists of endometrial cells, unfertilised ovum
  • Low viscocity blood and lack prothrombin, thrombin and fibrinogen that prevnt clotting - needs to leave the endometrium
19
Q

What happens during Day 1-7 proliferative/follicular phase?

A

Days 1-7 - P4 and E2 levels are low
- Endometrium shed then regrows; mestruation
- Increased GnRH secretion from the hypothalamus
- P4 and E2 decrease due to CL demise - Increased levels of FSH (-ve feedback from steroids)
- FSH act on ovarian follicular cells to increase E2 production
- Of several competing follicles , a single dominant follicle is selected. Other recruited follicles under atresia
- Endometrial glands mostly straight with evidence of mitosis

20
Q

What happens during days 8-14 of the proliferative/follicular phase?

A
  • Dominant follicle matures with the signifcant increase in size - secretes more E2 from increasing number of granulosa cells - endometrial proliferation and thickening
  • High E2 circulatinf levels exceed a certain threshold, switching to +ve feedback on LH production from anterior pituitary
  • LH surge induced; induced ~ 24-36 h later, follicle rupture - oocyte release - ovulation
  • ## Ovum picked up by fimbriae of fallopian tube and enters oviduct
21
Q

What is the luteal/secretory phase (days 14-28)?

A
  • Under influence of LH, Empty follicle converted into CL- secretes mostly P4 but also E2
  • P4 causes differentiation of endometrial glands to prepare for implantation
  • P4 maintains endometrium ; induces decidualisation
  • High P4 levels suppress LH and FSH release
  • Oocyte remains in oviduct
  • If no no fertilisation, CK degenerates - reduced P4
  • Vasoconstriction via prostaglandinds (pgS); ischaemia; no vascular support for endometrium, meneses
  • Low P4/E2 lebels- GnRH brake release. FSH and cycle begins again
22
Q

What is decidualisation?

A
  • The transformation of endometrial stromal cells cells to decidual cells by cAMP, progesterone
  • Secretory, glycogen-rich, lipid0rich cells
  • Early nutrition for embryo
  • Secrete prolactin (anterior pituitary)
  • Decidua rich in uterine NK cells
  • Plays a role in immune tolerance
  • Impaired decidualisation implicated in miscarriage, endometriosis
23
Q

What effect does the mesntrual cycle have on cervical mucus?

A
  • In proliferative phase
  • under E2 influence, mucus is thin, watery, stretch to aid sperm transport
  • Secretory phase
  • Thick impenetrable mucus
  • Basis of contraception
24
Q

What are some menstrual disorders?

A
  • Paindul period/cramps - dysmenorrhoea
  • Primary - absence of underlying pelvic pathology
  • Secondary - underlying pelvic pathology
  • Ovulation pain - Mittelschmerz (‘middle pain’)
  • swelling/stretching or ripture od follicle on ovary; bleed
  • PMS
  • Fluctuating hormone levels - mood swings, irritability, fatigue
  • affects 75% of women at some point in their lives
  • Absence/ Heavy/ irregular periods
25
Q

What is endomentriosis?

A
  • When endometrial tissue is found elswehere in the body/ outside of the uterus (e.g. ovaries f tubes, pelvic, periotoneum etc)
  • 10% global incidence in women pre-menopause
  • 6-7 year delay in diagnosis
  • Cause of infertility; adhesions may cause bowel obstructions
  • Bladder involvement may cause dysuria
  • Explants remain responsive to hormonal stimiulation
  • Causes retrogde menstruation
  • Inflammation , cytokines
  • Reduced apoptosis/stem cells
  • Angiogenesis/dossenmination through lymphatics
26
Q
  • What are leiomyamas (fibroids)?
A
  • Derived from the uterine smooth muscle (myometrium)
  • Hormone dependent - can enlarge and regress after menopause
  • Most common benign tumout in females ; no progression to cancer
  • Frequently manifests with menorrhagia, sometimes w metrorrhagia
  • often asymptomatic but sometimes vary
  • Associated with the presence of a mass (back pelvic pain or pressure), bloating, constipayed, urinary frequency, dyspaureunia
  • Pregnancy and infertility - can prevent blastocyst attatchement to the uterine wall
  • May block the fallopian tubes
  • Can lead to difficulties during labour may need c section
27
Q

What are the different types of fibroids?

A
  • Pedomculated submucosal fibroid
  • Intramural
  • Submucosal
  • Subserosal
  • Pedonculated
28
Q
A
29
Q

What are types of hypothalamic dysfunction (HPO )?

A
  • disordered gnrh released caused by:
  • stress
  • strenous exercise
  • excessive weight gain/loss
  • eating disorders
  • Jet lag
  • Pulsatile GnRH release disrupted
  • Ovulation affected
  • Altered sex steroids levels in circulation (E2 in blood)
  • Prolactinaemia, hyper/hypothyroidism, Cushing;s (amenorrhoea, anovulation)

Reproduction (22 decks)

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