Upload
hugo-bryan
View
225
Download
0
Tags:
Embed Size (px)
Citation preview
Sexual Reproduction in the Human
Learning objectives
• Outline the stages in the menstrual cycle
• Discuss the role of hormones in the menstrual cycle
• Discuss the Cause/Prevention/Treatment for fibroids or for endometriosis
Depth of treatment
• Detailed study of the menstrual cycle and hormonal control
Menstrual Cycle
Hormonal control in the menstrual cycle
• Four hormones involved:– FSH (Follicle Stimulating Hormone)– Oestrogen – LH (Luteinising Hormone)– Progesterone
• Each hormone causes the production of the hormone following it and inhibits the hormone preceding it
FSH – Follicle Stimulating Hormone
• Produced by pituitary gland• Produced early in the cycle (days 1-5)• Stimulates a few potential eggs to develop,
surrounded by graafian follicles• Only one usually survives• Sometimes used in fertility treatments to
stimulate ovaries to produce eggs – often lots of eggs develop. This explains some multiple births
• Each graafian folllicle then produces oestrogen
Oestrogen
• Produced by the graafian follicle in the ovary
• Produced from days 5 -14
• Causes the endometrium to develop
• Inhibits FSH ensuring no further eggs develop (useful in contraceptive pill)
• High levels of oestrogen just before day 14 stimulate release of LH
LH - Luteinising Hormone
• Produced by the pituitary gland
• Produced on day 14
• Causes ovulation
• Causes the remains of graafian follicle to develop into corpus luteum
• Corpus luteum makes final hormone in the cycle progesterone (along with small amounts of oestrogen)
Progesterone
• Produced by the Corpus Luteum in the ovary
• Produced from days 14-28
• Maintains structure of endometrium
• Inhibits FSH to stop further eggs developing
• Inhibits LH to stop further ovulation and pregnancies
• Prevents contractions of the uterus
Learning Check
• List the four hormones involved in the menstrual cycle
• In each case state where it is produced
• Give a function for each hormone
Contemporary issues and technology
• Menstrual disorders– one example of a menstrual disorder from the
following: endometriosis and fibroids– one possible cause, prevention and treatment
Menstrual disorder (Fibroids)
• Fibroids are tumours of the uterus
• They are the result of the overproduction of cells
• They do not invade other tissues and do not spread (benign)
• Slow growing - range from the size of a pea to the size of a melon
• Common between ages of 35 and 45
• Small fibroids often produce no symptoms
• As they enlarge they produce heavy and prolonged menstrual bleeding (this can lead to anaemia, pain, miscarriage or infertility)
Menstrual disorder (Fibroids)
Cause
• Cause is uncertain
• May be an abnormal response to oestrogen
• Can occur in women taking the contraceptive pill
Prevention and treatment
• Small fibroids require no treatment just monitoring to check their growth
• Large fibroids can be removed by surgery
• If many large fibroids are present a Hysterectomy may be necessary. This is where the uterus is removed
Menstrual disorder (Endometriosis)
• Growth of endometrial cells outside the uterus (often in fallopian tube)
• Normally endometrium is shed each month in the menstrual cycle. In endometriosis misplaced endometrium is unable to exit the body
• Results in internal bleeding, inflammation of surrounding area and pain
• Formation of scar tissue may result• If in the fallopian tube this can interfere with the
passage of eggs to the uterus (infertility)
Cause
• Exact cause remains unknown
• Several theories (response to excess oestrogen creation)
Prevention and treatment
• No known cure
• Hysterectomy (removal of uterus) - no guarantee that symptoms will disappear
• Medication can be taken to interfere with hormones resulting in a reduction or elimination of menstrual flow