Reproductive physiology and endocrinology Flashcards
1
Q
Describe the hypothalamic pituitary ovarian axis (3)
A
- Maturation of the GnRH secretory cells drives puberty
- Neurosecretory cells in the hypothalamus produce GnRH
- GnRH stimulates gonadotrope cells in the anterior pituitary to produce LH and FSH which act on the testes and ovaries
2
Q
Describe prolactin
-suppression
-stimulation
-function
-clinical implications
A
- Suppression
-Dopamine is released down the hypophyseal system from the hypothalamus. It acts to inhibit lactotrophs (the cells responsible for prolactin production) - Stimulation
-Thyrotropin releasing hormone is released by the hypothalamus. It stimulates lactotrophs to release prolactin
-Oestrogen stimulates lactotrophs directly to secrete prolactin - Fuction
-Promotes milk production in the mammary glands - Clinical implication
-Domperidone adn metocloprimide = dopamine antagonists
-Bromacriptine adn cabergoline (dostanex) = dopamine agonists
3
Q
Describe sterioogenesis of the mineralocoricoids, glucocorticoids and sex hormones (Flow chart)
A
4
Q
Describe estrogen
-Four forms
-How it is produced
-Transportation in the body
-Metabolic effects (7)
A
- 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 - 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 - Transport
-Bond reversibly to SHBG - Metabolic effects
-Hepatic production of binding protiens
-female sex characteristics
-Increased coagulation
-Lipogenesis
-Lower plasma cholesterol
-Water retention
-Calcification and bone growth
5
Q
Describe progestogens
-Main form
-Produced by
-Transport
-Metabolic effects (8)
A
- Main form = progesterone P4
- Production
-Made from cholesterol by the corpus luteum and adrenal gland.
-Made by the placenta in pregnancy - Transport
- Extensively bound to plasma proteins like albumin - 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
6
Q
Discuss androgens
-Types and where produced (4)
-Transport
-Metabolic effects (4)
A
- Type of androgen and site of production
-Synthesised in teste, ovaries, adrenal glands
-DHEA
-Andorestenedione
-Androstendiol
-Dihydrotestosterone - synthesised by 5 alpha reductase - Transported by sex binding globulin, albumin
- 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
7
Q
Discuss oogensis from the early fetus until ovulation during reproductive years (7 steps)
A
- At 6 weeks primative germ cells invade the primative streak and form a bipotential gonad
- In the bipotential gonad they are diploid - called oogonium
- 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
- Oogonium undergo prophase 1 and form a primary oocyte. This is arrested in this state until puberty
- At puberty there are around 400,000 primary oocytes - these are called primordial follicules
- Hormonal changes of puberty create primary follicles and Meiosis I is re-initiated producing secondary oocytes (haploid) + a polar body
- Secondary oocytes undergo meiosis 2 forming a further haploid + polar body
8
Q
Discuss the follicular phase of the ovulatory cycle
-Length
-Steps of follicule formation (6)
-Selection of dominant follicule (3)
A
- Length
-Variable. Average 14 days - 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 - 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
9
Q
Discuss ovulation in the menstrual cycle
-Effect of the LH surge (3)
A
- The LH surge activates meiosis II
- The granulosa cells become leutinised to be able to produce progesterone
- The walls of the follicule thin to allow ovulation 36 hrs after the LH surge
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
- Mensturation
-Progesterone production from CL stops
-The endometrium undergone ischemic necrosis of the stratum functionalis
-The CL becomes the corpus albicans - 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 - 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
