Lec 37- Endocrinology of reproduction Flashcards
Male reproductive physiology
-Tests (spermatogenesis) \+Sperm and testosterone -Epididymis and ductus deferens \+Maturation of sperm, storage and exit -Seminal vesicles \+Fructose, PG's, bulk of seminal fluid, clotting factors -Prostate \+Secretion alkalinises vagina, triggers clotting
Cells of testes (Sortoli)
Sertoli cells
- Blood testes barrier (tight junction)
- Nourishment of developing sperm
- Phagocytic
- Secretes fluid to flush sperm into epididymis
- Secretes ABP (adrogen binding proteins) to maintain high testosterone levels in tests
- Site of action of FSH and Testosterone
Leydig cells
-Interstitial cells (scattered between Sertoli cells)
-Endocrine cells located within connective tissue between seminiferous tubules
+Functionally distinct from site of spermatogenesis
-Secrete testosterone
+Steroid hormone derived from ChE
+Secreted into blood, bound to plasma proteins: Adrenogen binding proteins (ABP)
Hormone control of testicular function
-Work out a diagram to show the control of testicular function by hypothalamus and the pituitary
Spermatogenesis
- Continuous process
- Single sperm takes 64 days to mature
- 200 million present at any one time
- Not a good drug target because there are so many sperm produced and it is constant
Female reproductive anatomy
- Ovary: active endocrine organ
- Fallopian tubes
- Uterus
- Cervix
- Vagina
Follicular phase: Developing follicle secretes oestrogen
LOOK AT GREEN BOOK AT THE BACK
- Primary follicles ->
- Secondary Follicles ->
- Oocyte ->
- Mature follicle –>
- Ovulated oocyte ->
- Ruptured follicle ->
- Corpus luteum ->
- Regressing corpus luteum ->
Control of folliculogenesis
-Initiated by FSH
-Developing follicles secrete Oestrogen
+Stimulates further follicle maturation in ovary
+During follicular phase stimulates pituitary to secrete more FSH
-Ovulation caused by mid-cycle LH burst
-Corpus luteum formed
+Secretes progesterone
+With oestrogen and inhibin this inhibits pituitary and hypothalamus
Conception
1) Ovulation (egg release)
2) Day 1 fertililsation- zygote
3) Days 2-4- cell division takes place and zygote moves down the fallopian
4) Day 4-5: Blastocyst reaches uterus
5) 5-9 days- Blastocyst implants
Pregnancy
-Fertilisation
+Transport of Ovum and sperm to oviduct
+Zygote: sperm and egg nuclei fuse
-Blastocyst formation
+Moves to uterus
+Nourished by nutrients in ovum and endometrial secretions
-Implantation
+Usually occurs a week after fertilisation
+Uterus richly vascularised, secretary: ready
+Blastocyst outer layer (Trophoblast) performs implantation, it releases a hormone which prevents degeneration of the corpus luteum to keep progesterone levels high (this needs to be high throughout pregnancy to prevent loss of baby)
Implantation
-Trophoblast cells next to endometrium
+Secrete protein digesting enzymes
+Protrude into depths of endometrium
+Digest endometrial cells
-Carve out a hole in endometrium for the blastocyst
-Maske fuel and raw materials available for developing embryo
Now pregnant
Following implantation
-hCG (human chroionic gonadotropin) hormone secreted by developing chorion
+Functionally similar to LH
+Stimulates and maintains corpus luteum
+hCG is what is detected by pregnancy tests
-Prolongs life of corpus luteum
+Progesterone and oestrogen
Developing placenta
-Takes over as source of progesterone and oestrogen.. HPG remains inhibited
Female vs Male
Female -400 eggs released per lifetime -One per month -Fertile window following ovulation -Cyclical process Male -Spermatogenesis takes 64 days -BUT is a continuous process -200 million sperm per day released into tubule -Can all be released in a single ejaculate
Gonadotrophin releasing hormone from hypothalamus
- GnRH from the hypothalamus is released to act on the pituitary
- The pituitary then releases both LH (Luteinising hormone) and FSH (Follicle stimulating hormone)
1) LH acts on leydig cells to release testosterone which then has systemic roles as well as entering the Sertoli cells
2) FSH binds to Sertoli cells producing cAMP, this stimulates DNA and RNA transcription leading to protein synthesis of ABP - This then binds with the testosterone release from leydug cells and enter epididymis)
