Physiology - Gynaecology

Gynaecology

Physiology

·        GnRH:

·        10 amino acids – only lasts seconds Þ requires portal circulation 

· Pulsitile release

·        Stimulates release of FSH + LH

·        Inhibited by progesterone (strongest inhibitor), PRL, inhibin, testosterone, oestrogen, stress 

· FSH: acts on germ cells

·        LH: acts on supporting tissue:

·        Male: Leydig cells ® testosterone

·        Female: Thecal cells ® testosterone ® acted on by aromatase (produced by granulosa cells) ® oestradiol

·        Oestrogen: three types:

·        Oestradiol: ovary

·        Produced by follicles

·        ® ­Mucus

·        -ive feedback on FSH

·        Above a threshold ® ­LH

·        Unopposed oestradiol causes endometrial hyperplasia – growth without the maturing effect of progesterone

·        Oestriol: placenta

·        Oestrone: metabolised from androgens (eg testosterone) by adipose tissue · Female fetus has several million eggs, by puberty has 300 – 400 eggs · Follicle at ovulation is 2 cm

·        Infection control:

·        Sperm carry bacteria and viruses into uterus. If mucus inhibits sperm ® ¯infection, which would otherwise cause inflammation and ¯chances of implantation

·        ­Oestrogen ® Vaginal epithelium thickens during cycle ® ­glycogen ® ­lactobacilli ®­acidity ® ¯other bacteria

·         Menstrual Cycle:

·        Inhibin from developing follicle suppresses FSH compared with LH ® LH surge

·        Phases for uterus endothelium: menstrual ® proliferative/follicular ® secretory/ progestational 

·        Human Chorionic Gonadatrohpin (hCG) from implanted zygote signals corpus luteum to continue progesterone production.