Lecture 9- Reproductive System Flashcards
When does the menstrual cycle begin?
When the superficial layer of uterine endometrium is shed
When does the endometrium regenerate?
Follicular phase of the cycle after menstrual flow has stopped
Where is Gonadotrophin-releasing hormone secreted from?
Peptidergic neurons in the hypothalamus in a pulsatile manner
What does the GnRH stimulate the anterior pituitary to release?
Gonadotrophic hormone; Follicle stimulating hormone (FSH) Luteinising hormone (LH)
Where does the gonadotrophic hormone act on?
Ovaries to stimulate the release of oestradiol, progesterone and other ovarian hormones
What does Graafian follicle release ?
Oestrogen
What effect does GnRH have on anterior pituitary which releases FSH and LH?
Positive effect
What is FSH responsible for ?
Development of Graafian follicle over the first part of menstrual cycle Lead to ovulation
What is LH responsible for ?
Maintaining the corpus lutetium
What is the 2 phases of menstrual cycle?
Pre-ovulation follicular phase Post-ovulation luteal Phase
Where does oestrogen have a negative feedback on?
Anterior pituitary and hypothalamus
What happens in the first 14 days ?
Development of Graafian follicle and production of more oestrogen
What is the role of oestrogen?
Stimulate the expression of more progesterone receptors within uterine lining therefore promoting the effects of progesterone in development of uterine lining
What does a gradual level of oestrogen do ?
Prompt a surge level in FSH and LH
What does surging LH promote ?
Ovulation
What is the role of progesterone in late phase of cycle?
Proliferation of endometrium lining For implantation of fertilised ovum
What is the uses of oestrogen ?
- Hormone Replacement Therapy a) hypo-ovarian conditions b) menopause 2. Contraception 3. Menstrual disorders
What is the uses of progestogen?
- Hormone Replacement Therapy 2. Contraception 3. Endometriosis 4. Endometrial Cancer
What is the uses of Androgens?
- Male contraception 2. Androgen Replacement Therapy ?
What is the most important synthetic form when looking at contraception?
Ethinyloestradiol
What is the role of Hormone Replacement Therapy?
To maintain bone integrity
What does drop in oestrogen level lead to
Osteoporosis
What happens with fluctuations of oestrogen level?
Predisposed to some form of cancer
What have been used in male contraception?
Progesterone and progesterone derivative
What are anti-oestrogen?
Compound that block oestrogen receptors
What is clomiphene?
Causes pituitary gland to release a hormone needed to stimulate ovulation non-steroidal oestrogen receptor antagonist Administered during early part of cycle Ovulation rates greater with clomiphene Therapy
What does Clomiphene block?
Negative feedback to hypothalamus and pituitary GnRH, FSH and LH secretion are increased as a result of the block to the negative feedback
What is the main aim of contraceptive mechanism?
Suppress mid cycle FSH and prevent LH surge
What is more potent than progesterone ?
Oestrogen
Fallopian tube
Progestogen inhibit motility Oestrogen enhances motility causing abnormal rates of ovum transport
Ovary
Estrogen inhibit ovulation by blocking Gn surge Progestogen much weaker but has same effect
Endometrium
Sustained levels of estrogen or progestogen cause asynchronous development Less receptive to implantation
Cervical mucus
Progestogen causes secretion of thick viscid mucus hostile to sperm
What has be done incorporated as long acting formulation?
Levonorgestrel
What is a major constituent of contraceptives ?
Synthetic compound Ethinyloestradiol
What does combined oral contraceptive pill contain?
Oestrogen and progesterone
What is oral contraceptive pill efficacy reduced by?
Broad-spectrum antibiotics
What does broad-spectrum antibiotic do?
Reduce enterohepatic recirculating of oestrogen by killing gut flora
What can oral contraceptive pill be used for?
Normalise abnormal periods/abnormal menstrual cycle
What does oestrogen inhibit ?
Secretion of FSH
Suppresses development of the ovarian follicle
What does progesterone inhibit?
Secretion of LH Prevent ovulation Make cervical mucus less suitable for the passage of sperm
Why does oestrogen and progesterone act in concert?
Alter the endometrium
What is the function of oestrogen and progesterone ?
Regulation of the reproductive cycle
What can combined contraceptive pill lead to?
Cardiovascular disorders
What can oestrogen can regulate ?
Levels of circulating lipids
What are the benefits of contraceptive pill?
Reduction in ovarian/endometrial cancer risk HDL/LDL (oestrogen) Normalise dysfunctional uterine bleeding
What are the drawbacks of contraceptive pill?
Association between use and breast/cervical cancer risk Thromboembolism Ischaemic heart disease/stroke Hypertension HDL/LDL (progestogens) Androgenic effects (progestogens) Mood
What is the progestogen only pill?
Low dose progestogen Ovulation still takes place Menstruation is normal
What is the mechanism of action of progestogen only pill?
Thickening of cervical mucus preventing sperm penetration Causes suppression of gonadotrophin secretion and occasionally ovulation
What is the 12-month pregnancy rates?
1-13%
What is the alternative methods of contraceptive delivery?
- Injection 2. Patch 3. Vaginal ring
Where does male contraceptives act upon?
Testes to stimulate the production of Testesterone from Leydig cells and to promote the development of sperm within Sertoli cells
Where does testosterone have negative feedback on?
Level of pituitary and hypothalamus
What is another term for progestogen?
Gestagen
Where are new sperm cells created?
Testicles
Where is Vasalgel injected?
vas deferens as a contraceptive
What is gas deferens?
Tube that sperm pass through on the way to the penis
What is contraceptive?
Long acting and reversible
What is Viagra?
Drug that blocks the enzyme phosphodiesterase V
