Reproductive physiology Flashcards
What is the function of fimbriae?
Grasp and pull a secondary oocyte from the ovaries into the Fallopian tube so it can travel into the uterus
What other adaptions does the fallopian tube have?
Lots of longitudinal folds which help massage ovum along the tube
Describe the anatomy of the uterus and how its adapted to its function?
- Thick and muscular myometrium which helps in expelling the foetus during birth
- Very large blood supply
What is the difference between oogenesis and spermatogenesis?
- New gametes made every day in spermatogenesis whereas in oogenesis all gametes made before birth and mature as puberty progresses
Describe oogenesis
- At birth women already have oogonia (diploid) which undergo mitotic division to form primary oocyte (diploid) before they are born
- Meisois I then stops until the women reaches puberty where starts to ovulate, secondary oocyte (haploid) is formed and first polar body released completing meiosis I and starting Meiosis II
- at fertilisation secondary oocyte is fertilised by sperm cell completing meiosis II
- forms ovum and second polar body
- the nuclei of sperm cell and ovum then unite to form a zygote (diploid)
Describe spermatogenesis
- Start with spermatogonium which undergoes mitotic division to from primary spermatocyte (diploid)
- Spermatocyte (haploid) divides to from two secondary spermatocytes
- these divide to form two spermatids each
- Undergo spermiogenesis (haploid and half the amount of chromosomes as spermatocytes) to become spermatozoa
Describe the genetic material in a primary oocyte?
Two sets of each paired chromosomes, Diploid
Describe genetic material in a secondary oocyte?
Two of each chromosome still but not paired, Haploid
What is released on conversion of primary to secondary oocyte?
Polar body carrying half the chromosomes (paired)
What are the two phases of the ovarian cycle and how long are they?
1) follicular phase (day 1-14)
- variable may take less than 14 day can only take 7
2) luteal phase (day 14-28)
Describe the follicular phase of the ovarian cycle?
- primordial follicle containing the primary oocyte are stimulated by FSH (follicle stimulating hormone) to develop
- granulosa cells surrounding the oocyte also start to divide and secrete zona pellucida which surrounds the oocyte and recruit theca cells which also continue to replicate
- start to develop follicular antrum (filled filled space within cell)
- antrum continues to grow until starts to poke outside the ovary where you get ovulation
- only one of the few cells which start to mature will become a graafian follicle and rest die becoming atretic
Describe the luteal phase of the ovarian cycle?
(maintenance phase)
- Follicle starts to secrete VEGF (vascular endothelial growth factor)
- VEGF causes follicle to fill with blood
- theca cells differentiate and become swollen with fat deposits (now called corpus luteum)
- Corpus luteum produces progesterone which allows for maintenance of uterine wall
- if oocyte has been fertilised corpus luteum is maintained but if no pregnancy than corpus luteum breaks down which is what causes menstruation as no hormones released from the luteum maintaining it
What is mittelschmerz pain?
Pain which occurs in the middle of the menstrual cycle due to blood leakage into the peritoneum from the follicle
Describe hormonal control in men?
- Gonadotrophin releasing hormone is released every night
- Ensures gametes are constantly formed
Describe hormonal control in women?
- Hypothalamus releases GRH at the start of every ovarian cycle
- this stimulates release of LH and FSH by anterior pituitary
- FSH stimulates follicular development which in turn means more granulosa cells are being produced which release oestrogen’s
- oestrogen’s have feedback loop where they turn off release of FSH and GRH and LH (in small doses)
- LH also stimulates development of theca cells which release androgens which turn into oestrogen’s contributing to this negative feedback
