repro 3.1- puberty and the menopause Flashcards
What are primary sexual characteristics?
internal and external genitalia, established before birth, but immature.
when do secondary sexual characteristics develop?
The changes that occur during puberty
Give examples of secondary sexual characterstics of the female
-thelarche (breast development)
-Menarche (first period)
-growth spurt
puberache- axillae and pubic hair
When do girls experience puberty?
8-13
Give examples of male secondary sexual characteristics.
testicular growth
growth spurt
deepening of voice
puberache
When do boys experience puberty?
9-14 years
What’s the first change to happen in females and males during puberty?
females- breast bud development
males- growth of the testicles
Why do males grow taller than females?
Their growth spurt begins later and lasts longer (due to no oestrogen closing the epiphyseal growth plates early).
What is required for puberty to happen?
Rise in GnRH levels, causing a rise in FSH and LH levels.
What is thought to cause the rise in GnRH levels?
development and maturation of central mechanisms.
Removal of inhibition to the hypothalamus
a critical weight being achieved (47Kg)
What does higher androgen levels cause?
-pubic and axillary hair growth
What does the rise in oestrogen cause (characteristic wise)
breast development (breasts have oestrogen receptors, which is what allows for cell growth)
What is the growth spurt caused by?
growth hormone, increased metabolic rate, increased androgens.
What is the critical weight needed for puberty to occur?
47kg.
Why might puberty be occuring earlier and earlier?
increased nutritional status, larger people,
What is precocious puberty?
puberty that happens 2 SD below mean, so <8 years for girls, <9 years for boys.
How can precocious puberty be classified?
true/complete- due to early maturation of the HPG axis.
False/incomplete- ovarian/testicular/arenal secretion of homrones.
Give some causes of true precocious puberty
meningitis
pineal cysts
post-infectious encephalitis
primary hypothyroidism.
How does primary hypothyroidism lead to precocious puberty
Hormonal mechanism not well understood, may be due to the low levels of thyroid hormones leading to an increase in TRH and GnRH, thus puberty gets started early.
Give some caused of false precocious puberty
ovarian cysts
ovarian/testicular tumours
congenital adrenal hyperplasia
How would you distinguish between true and false precocious puberty?
Blood tests to look at the GnRH, LH, FSH and androgen levels.
What are some main consequences of precocious puberty?
early closure of the epiphyseal growth plates, leading to short stature.
Family/child distress, eg due to bullying
increased risk of sexual abuse.
What’s the name given to the end of reproductive life for the female?
Climacteric.
How can the climacteric be further subdivided?
pre-menopause
menopause
post-menopause
When does the pre-menopause happen and what does it involve?
around 40 years old Shortening of the follicular phase, sometimes menarche will happen without ovulation Falling oEstrogen levels increasing FSH and LH levels. Reduced fertility
Why do FSH and LH levels rise?
less oesotrogen is being produced, so there’s less negative feedback, so less inhibition of GnRH and therefore LH/FSH.
which hormone rises faster, FSH/LH. Why?
FSH, along with less negative feedback due to less oestrogen, there is also less inhibin production so there is a 2 fold reduction in inhibition.
When does the menopause happen?
Around age 50.
What are some symptoms of the menopause?
itchy twitchy sweaty sleepy bloated moody forgetful hot flushes
What happens in the menopause?
Complete cessation of menstrual periods, no more follicles left.
the uterus shrinks,
loss of vaginal rugae,
involution of breast tissue
What happens to the bone in menopause?
decreased density by up to 2.5% per year, less oestrogen so less inhibition of osteoclast activity.
What can be given to relieve the symptoms of the menopause?
Hormone replacement therapy, oestrogen and progesterone
Why should most woen not take oestrogen only HRT?
if they have a uterus, oestrogen can act on receptors and cause excessive growth, which increases the risk of cancer.
Only women who have had a hysterectomy can take oesrogen on it’s own.
How is HRT given?
Orally
topically
what are the main associated risks of HRT?
increased risk of breast cancer (and womb cancer in those who have had a hysterectomy).
