Session 3 - Puberty and the Menopause Flashcards
When are primary sexual characteristics established?
Before birth
In which gender does puberty begin first?
In females
When does male puberty begin?
9-14 years of age
Give six key changes in males at puberty
o Genital development begins o Pubic hair growth (Adrenarche) o Spermatogenesis begins o Growth spurt (10cm/year) o Genitalia adult o Pubic hair adult
How many stages are there in male puberty?
5
In general, what two things measure male puberty?
Genital development
Pubic hair
What are the three main “arche” of female development
Thelarche
Adrenarche
Menarche
What is the thelarche?
The breast bud
WEhat is the adrenarche? When does it begin?
Pubic hair growth
9.5 - 14.5
What is menarche? When does it begin?
Onset of menstrual cycle
12.25 -12.5 years
What are the four main features of female puberty
o Breast bud (Thelarche) – the first sign that puberty has begun.
o Pubic hair growth (Adrenarche) (9.5 – 14.5)
o Growth spurt (9cm/year) (12)
o Onset of menstrual cycles (12.25 – 12.5) (Menarche)
What hormonal factors is the start of puberty associated with?
Pulsatile GnRH secretion leads to steady rise in FSH and LH.
Why does GnRH rise at the start of puberty? (2 possible reasons)
Rise in GnRH due to reduced sensitivity to -‘ve feedback by steroids
OR
Maturation of central secretory mechanisms
Why are boys larger than girls?
Growth spurt longer and slightly faster in males than in females
How does the growth spurt end?
Both sexes by epiphyseal fusion
What is the most critical factor in timing the onset of puberty?
Body weight
What is the critical weight for start of menarche?
47kg
If body weight falls significantly below this the reproductive cycle ceases
Signalled to brain by leptin from adipose tissue
What is growth spurt start weight in a) males and b) females
a) Males - 55kg
b) Females - 30kg
What is the adrenarche dependent on in a) males and b) females
a) Males - Testosterone
b) Females - Androgens in females
Why do girls have a shorter growth spurt than males?
Oestrogen closes epiphyses earlier in girls. Oestrogen is needed to initiate the growth spurt, but once levels reach a certain point it causes the epiphyses to fuse.
Why has the age of menarche decreased over the past 200 years?
Better nutritiion - menarche triggered by weight gain (47kg)
What does the pineal gland detect?
Light
What does the pineal gland secrete?
Melatonin, which is theorised to induce puberty.
What is the significance of pineal tumours?
Can influence puberty in humans
What is precocious puberty?
Early activation of puberty
Before 8 in girls
Before 9 in boyrs
What two neurological causes of precocious puberty?
Pineal tumours
Meningitis
Give an endocrine causes of precocious puberty
Uncontrolled gonadotrophin or steroid secretion
from hormone secreting tumours
Give a lifestyle cause of precocious puberty
Obesity
Increased leptin secretion from adipose tissue
Why are men larger than women?
Growth spurt is longer and faster
What is growth spurt dependent on
Growth hormone and steroids in both sexes
What is the thelarche dependent on?
Dependent on oestrogen
Gynaecomastia can occur as a result of conversion of testosterone to oestrogen in adipose tissue
What is the development of male genitalia dependent on?
Testosterone
What is the pre-menopause?
Three changes involved
Occurs at ?40 years
Involves changes in menstrual cycle including
- Shortened follicular phase with early or absent ovulation
- Less oestrogen secretion
- Less -‘ve feedback, so LH and FSH levels rise
- FSH rises more due to loss of inhibin
Reduced fertility
What is the menopause?
Cessastion of menstrual cycles at around 49-50. Occurs when female runs out of follicles.
What are the main hormonal changes that take place in the menopause?
Less -‘ve feedback from oestrogen so LH and FSH levels rise
FSH rises dramatically
What are the three mains sites of menopausal effects?
Vascular
Oestrogen sensitive tissues
Bone
What occurs in vascular tissue in the menopause
Hot flushes
Transient rise in skin temperature
How can hot flushes be relieved in the menopause?
Oestrogen administration
Name 6 changes in oestrogen sensitive tissues due to menopause
o Uterus o Thinning of cervix o Vaginal rugae lost o Involution of some breast tissue o Changes in skin o Reduction in bladder tone
Give three effects of menopause specific to the uterus
Regression of endometrium
Shrinkage of myometrium
Shrinks away into a very small organ
What happens to bone post-menopause?
o Bone mass reduces by 2.5% per year for several years
o Increased reabsorption relative to production
o Osteoporosis
Much greater in some than others
Major reason for fractures in later life
Can be limited by Oestrogen therapy
What is hormone replacement therapy?
Hormones administered to relieve symptoms of menopause
How is HRT adminstered?
Orally or topically be patch or gel
What are the two main benefits of HRT?
Can limit osteoporosis
Relieves menopause syptoms
