Reproductive System 3 PDF

SCAN QR code to register your interest 1 Reproductive System 3 Female physiology & conception to placentation Dr Megan Kelly: [email protected] Female Physiology: Summary of Ovarian Cycle Estrogen à positive feedback...

SCAN QR code to register your interest 1 Reproductive System 3 Female physiology & conception to placentation Dr Megan Kelly: [email protected] Female Physiology: Summary of Ovarian Cycle Estrogen à positive feedback But what is happening in the uterus during these events? Learning Objectives: Blue text & headings= important! Black = learn once you know the blue info well Grey = for interest only if you already Lecture 3: part 1 know the blue & black info well üDescribe the process of oogenesis & compare it to spermatogenesis üExplain in brief the sequence of events in the ovarian cycle including: ü Follicular phase (folliculo-genesis) ü Luteal phase (luteo-genesis & lysis) üExplain the basics of hormonal regulation of the female reproductive system üExplain in brief the sequence events in the uterine cycle including: ü Menstruation ü Proliferation phase ü Secretory phase üEffects of estrogen & menopause Marieb & Hoehn, 10th Ed, Human Anatomy & Physiology. Chapter 27 pages 1045 - 1064 Available online at the UOW library, click here or copy the URL below 4 https://ebookcentral.proquest.com/lib/uow/reader.action?docID=5176166 Female physiology: The uterine cycle 2. The proliferative phase: ü From day ~6 -14 (variable duration) ü Endometrium is re-built as estrogen is produced in increasing quantities by the dominant ovarian follicle ü Rising estrogen levels also ü Thins the cervical mucus, allowing channels for sperm to move through ü Activates fimbriae in the uterine tubes, ready to scoop up the ovulated oocyte Endometrial layer consists of spiral and straight arteries. Spiral arteries continually regenerate and degenerate with each cycle, nourishing the functional layer. Straight arteries service the basal layer. Stem cells in the basal layer form the new endometrial functional layer each cycle.  Female physiology: The uterine cycle 3. The secretory phase: ü After ovulation, for a consistent 14 days ü Preparation for pregnancy by progesterone from corpus luteum ü Thick, nutrient rich, very vascular endometrial tissue for implantation of embryo ü Increase thickness of cervical mucus preventing sperm entry ü If no fertilization & implantation occurs, the corpus luteum degenerates ü No corpus luteum à less ovarian hormones à menses Female physiology: The uterine cycle 1. The menstrual phase: ü First 1-5 days (easiest to pinpoint!) ü Gonadal hormone levels are low as the corpus luteum degenerates (progesterone) and there is no new dominant follicle yet (estrogen) ü Without these hormones, blood vessels in the endometrium atrophy and the tissue dies & sheds (pain, bleeding) = menses Female Physiology: Putting it all together Ovarian cycle: Follicular phase Ovulation – caused by a surge in LH Luteal phase Uterine cycle: Menstrual phase Proliferative phase Secretory phase Page 1109 – Fig 27.25 Female Physiology: Effects of Estrogens & Progesterone Together with GnRH, FSH & LH: regulate cycles Takes ~4 years to fully balance out Progesterone: ü Promotes gestation – literally “pro” and “gestation” = progesterone ü Highest levels in the secretory phase of uterine cycle – allowing implantation of embryo into thick, nutrient dense endometrium ü Also thickens cervical mucus to stop new sperm messing with a developing embryo ü First produced by corpus luteum, then placenta ü Also aids estrogen during development Female Physiology: Effects of Estrogens & Progesterone Estrogens: Together with GnRH, FSH & LH: regulate cycles Puberty: Takes ~4 years to fully balance out ü Growth, fusion of epiphyseal plates ü Maturation of the reproductive tract ü Secondary sex characteristics: Breast development Subcutaneous fat deposition (especially hips & breasts) Wider & lighter pelvis for childbearing Produced by follicles as well as the corpus luteum High estrogen causes positive feedback to initiate the LH surge & ovulation Metabolic: ü Maintain low cholesterol (and high HDL) ü Facilitate calcium uptake (skeletal density)  Female Physiology: Menopause 1. Ovarian function gradually declines after 20 yrs of age By 30, there are about 100,000 oocytes left but their quality has declined – lower fertility By age 50, there are around 1,000 oocytes left During a