Reproductive physiology and endocrinology Flashcards

1
Q

Describe the hypothalamic pituitary ovarian axis (3)

A
  1. Maturation of the GnRH secretory cells drives puberty
  2. Neurosecretory cells in the hypothalamus produce GnRH
  3. GnRH stimulates gonadotrope cells in the anterior pituitary to produce LH and FSH which act on the testes and ovaries
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2
Q

Describe prolactin
-suppression
-stimulation
-function
-clinical implications

A
  1. Suppression
    -Dopamine is released down the hypophyseal system from the hypothalamus. It acts to inhibit lactotrophs (the cells responsible for prolactin production)
  2. Stimulation
    -Thyrotropin releasing hormone is released by the hypothalamus. It stimulates lactotrophs to release prolactin
    -Oestrogen stimulates lactotrophs directly to secrete prolactin
  3. Fuction
    -Promotes milk production in the mammary glands
  4. Clinical implication
    -Domperidone adn metocloprimide = dopamine antagonists
    -Bromacriptine adn cabergoline (dostanex) = dopamine agonists
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3
Q

Describe sterioogenesis of the mineralocoricoids, glucocorticoids and sex hormones (Flow chart)

A
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4
Q

Describe estrogen
-Four forms
-How it is produced
-Transportation in the body
-Metabolic effects (7)

A
  1. Forms of estrogen
    -Oestrone E1 - dominant during post menopause from ovaries and adipose
    -Oestradiol E2 - dominant during reproductive years from granuulsa cells
    -Oestriol E3 - dominant during pregnancy from placenta and E1 and E2 conversion in adipose tissue
    -Estetrol E4 - in pregnancy only produced by fetal liver
  2. Production
    -Theca cells respond to LH increase and increase cholesterol uptake
    -Increased cholesterol allows for increased adrogen production
    -Granulosa cells convert androgens to oestrogen with aromatose enzymes
    -Aromatase activity is stimulated by FSH
  3. Transport
    -Bond reversibly to SHBG
  4. Metabolic effects
    -Hepatic production of binding protiens
    -female sex characteristics
    -Increased coagulation
    -Lipogenesis
    -Lower plasma cholesterol
    -Water retention
    -Calcification and bone growth
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5
Q

Describe progestogens
-Main form
-Produced by
-Transport
-Metabolic effects (8)

A
  1. Main form = progesterone P4
  2. Production
    -Made from cholesterol by the corpus luteum and adrenal gland.
    -Made by the placenta in pregnancy
  3. Transport
    - Extensively bound to plasma proteins like albumin
  4. Metabolic effects
    -Shifts endometrum to secretory phase
    -Thickens cervical mucus
    -Decreases immune response in pregnancy
    -Inhibits lactation during pregnancy
    -Aids in breast development
    -Maintains pregnancy
    -Antagonises aldosterone
    -Helps to regulate bleeding in menstral cycle with progesterone withdrawl bleed
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6
Q

Discuss androgens
-Types and where produced (4)
-Transport
-Metabolic effects (4)

A
  1. Type of androgen and site of production
    -Synthesised in teste, ovaries, adrenal glands
    -DHEA
    -Andorestenedione
    -Androstendiol
    -Dihydrotestosterone - synthesised by 5 alpha reductase
  2. Transported by sex binding globulin, albumin
  3. Metabolic effects
    -Sexual embryological development of testes and secondary sexual characteristics of men
    -Protein synthesis and muscle mass
    -Increased glycolysis and fatty acid synthesis
    -Increased bone mass
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7
Q

Discuss oogensis from the early fetus until ovulation during reproductive years (7 steps)

A
  1. At 6 weeks primative germ cells invade the primative streak and form a bipotential gonad
  2. In the bipotential gonad they are diploid - called oogonium
  3. In the gonad the cells proliferate by mitosis to reach a maximum of about 7 million in T2. At birth there are about 1-2 million
  4. Oogonium undergo prophase 1 and form a primary oocyte. This is arrested in this state until puberty
  5. At puberty there are around 400,000 primary oocytes - these are called primordial follicules
  6. Hormonal changes of puberty create primary follicles and Meiosis I is re-initiated producing secondary oocytes (haploid) + a polar body
  7. Secondary oocytes undergo meiosis 2 forming a further haploid + polar body
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8
Q

Discuss the follicular phase of the ovulatory cycle
-Length
-Steps of follicule formation (6)
-Selection of dominant follicule (3)

A
  1. Length
    -Variable. Average 14 days
  2. Steps of follicule formation
    -20 primodial follicules develop into 20 primary follicules at the start of the menstural cycle. These can respond to LH and FSH
    -FSH stimulates the primary follicules to become secondary follicules -meiosis 1 re-initiated and proliferation of granulosa cells and development of zona pellucida
    -Theca cells surrounding the granulosa cells respond to LH and produce androgens
    -FSH stimulates aromatase in the granulosa cells and androgens are converted to oestrogen
    -Fluid is formed in the follicule to produce an antral cavity. This is now a mature follicule
    -The follicules secrete oestrogen which has a negative feedback on the hypothalamus and levels of FSH and LH drop
  3. Selection of the dominant follicule
    -As the LH and FSH levels drop smaller follicules are no longer supported and only the largest follicule survives.
    -At mid cycle the oestrogen has a positive feedback to the hypothalamus causing an LH surge
    -Inhibin prevents the positive feedback increasing FSH
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9
Q

Discuss ovulation in the menstrual cycle
-Effect of the LH surge (3)

A
  1. The LH surge activates meiosis II
  2. The granulosa cells become leutinised to be able to produce progesterone
  3. The walls of the follicule thin to allow ovulation 36 hrs after the LH surge
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10
Q

Describe the uterine cycle
-Mensturation Day 1-5 (3 points)
-Proliferative stage Day 6-14 (4 points)
-Secretory phase Day 14-18 (6 points)

A
  1. Mensturation
    -Progesterone production from CL stops
    -The endometrium undergone ischemic necrosis of the stratum functionalis
    -The CL becomes the corpus albicans
  2. Proliferative phase
    -Initiated by oestrogen
    -Stratum functionalis and spiral arteries are regenerated
    -Frequent mitosis of endometrial glandular epithelium
    -Proliferation of uterine glands
    -Cervical mucos is thin
  3. Secretory phase
    -Initiated by progesterone
    -Mitosis stops
    -Uterine glands become lined with columnar cells which become filled with lipids adn glycogen
    -Increase in angiogenesis
    -Cervical mucus thickens
    -Endometrial stroma becomes decidulaized
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