Female Reproductive System Flashcards
What are the functions of the uterus?
- maintenance of foetus during development
- expelling foetus at end of pregnancy
- major female hormone-responsive reproductive organ
What is the size of the uterus at the third trimester compared to at the start?
50cm vs 0.1cm
What is the duration and frequency of periods?
between 2-7 days every 28 days
How many periods does a woman normally undergo?
~450
What does each follicle contain?
one oocyte (unfertilised egg cell)
How many egg cells do the ovaries hold at different stages of development?
- midgestation = 6-7 million
- at birth = 2 million
- at puberty = 400,000
What are the 2 alternative phases of the ovarian cycle?
- follicular phase – dominated by presence of maturing follicles
- luteal phase – characterised by presence of corpus luteum
Which hormones do the ovaries produce and what do they do?
oestrogen and progesterone which act together to promote fertilisation of the ovum and to prepare the female reproductive tract for pregnancy
What is oogenesis?
the signalling pathway that causes maturation of the ovum
What is a follicle?
the combination of the developing egg (oocyte) and surrounding granulosa cells
What does GnRH do?
stimulate the anterior pituitary to release LH and FSH
What do FSH and FSHR combine to produce?
oestradiol
What type of hormone are FSH and LH?
peptide hormones
What does FSH do?
- aid in follicle growth and maturation
- induce antrum formation
What is the antrum?
fluid-filled space that develops among the follicle cells and where oestrogen is stored
What does inhibin do?
regulate the development of the follicles by inhibiting FSH secretion resulting in a surge in LH secretion
What do rising levels of oestrogen act on?
- hypothalamus to inhibit GnRH secretion (decrease FSH, LH)
- pituitary to inhibit FSH secretion
What happens as the follicle matures?
rising high levels of oestrogen act on the hypothalamus and pituitary to increase GnRH and selectively stimulate LH secretion (positive feedback)
What does the corpus luteum do under the influence of LH?
secrete both oestrogen and progesterone
What does progesterone do?
inhibit both LH and FSH secretion
What happens when there is no LH or FSH?
new follicular maturation and ovulation is prevented then the corpus luteum degenerates and no oestrogen or progesterone is produced i.e. the negative feedback is inhibited and a new follicular phase then begins
What are the 8 stages of the ovarian cycle?
- GnRH produced by hypothalamus
- FSH and LH produced by anterior pituitary
- slightly elevated oestrogen and inhibin levels
- high oestrogen level positively regulates GnRH secretion
- LH surge
- ovulation
- unfertilised egg is removed during the period
- oestrogen, progesterone and inhibin negatively regulate GnRH secretion
What does the menstruation cycle do?
prepare the female reproductive tract for fertilisation and implantation of an ovum
What are the 3 phases of the uterine cycle?
- menstrual phase
- proliferative phase
- secretory phase
What is ovulation?
when the egg is released via high levels of LH
What do remnants of the follicles do?
make progesterone which thickens the uterus lining in preparation for implantation of a fertilised egg
What happens as progesterone levels increase?
the body temperature increases by 0.5ºC
When does ovulation begin?
~10-14 days before menstruation
What is puberty triggered by?
increased level of GnRH
What are the signs of puberty?
- thelarche (earliest) – development of breasts
- pubarche – growth of pubic and axillary hair
- menarche – the first menstrual period
What changes does puberty cause?
- growth of the secondary sex organs
- fat deposition (especially around the hips)
- rapid increase in height (growth hormone)
What is menopause?
a decrease in hormone secretion that occurs between the ages of 45-55
What are the signs of menopause?
- cessation of menstrual cycles (12 months after last menstrual period)
- gradual atrophy of genital organs
- vasomotor changes (regulation of blood vessel dilation and constriction leading to hot flushes)
- skin changes
- psychological, emotional changes
- ↑ cholesterol levell – risk of cardiovascular disease
- ↑ risk of osteoporosis (decreased bone mass due to less oestrogen)
What can be used to treat menopause?
hormone replacement therapy (HRT)
What is amenorrhea?
a lack of menstrual bleeding characterised by the failure of onset of menstrual periods by age 16 (e.g. Turner’s syndrome)
What can accompany menstruation?
- dysmenorrhea (pain)
- menorrhagia – excessive bleeding e.g. uterine fibroids
- metrorrhagia – vaginal bleeding e.g. prior menopause
What can infertility be caused by?
- disorders of central-hypothalamic-pituitary function
- disorders of the ovary
- disorders of the uterus, uterine tubes and vagina
What happens if the HPO is not synchronised?
the woman is unable to ovulate
What do oestrogen disrupters do?
mimic the activity of oestrogen in the body’s cells
What do oestrogen disrupters do in females, males and animals respectively?
- females = ↑ breast tumours
- males = ↓ sperm count
- animals = gender bending
What does each endocrine gland in the female reproductive system produce?
- hypothalamus = GnRH
- anterior pituitary = FSH and LH
- ovaries = oestrogen, progesterone, inhibin and androgen
What are the development and transition stages in males and females?
- males = descent of testes, puberty
- females = puberty, menopause
