Lecture 4.2: Puberty and the Menopause Flashcards
What is Puberty? What occurs during it?
- Development of reproductive maturity
- Secondary sexual characteristics
- Gamete production/maturation
- Behavioural changes necessary for reproduction
Tanner Staging: Stage 1
Hormone release begins but no physical changes
Tanner Staging: Stage 2
First physical changes noticeable
* Girls: breast bud
* Boys: testes and scrotum enlargement
Tanner Staging: Stage 3
Growth spurts, physical changes progress
* Girls: fat deposits on hips in girls
* Boys: voice cracking and nocturnal ejaculation
Tanner Staging: Stage 4
Key functional events
* Girls: menarche
* Boys: spermatogenesis
Tanner Staging: Stage 5
Adult physical appearance and function
* Girls: regular periods and ovulation
* Boys: facial hair and musculature
Age of onset of puberty in girls
8-13
What is Adrenarche
Beginning of pubic hair growth
Breast Development: Stage 1
No glandular breast tissue palpable
Breast Development: Stage 2
Breast bud palpable under areola (1st pubertal sign in females)
Breast Development: Stage 3
Breast tissue palpable outside areola; no areolar development
Breast Development: Stage 4
Areola elevated above contour of the breast, forming “double scoop” appearance
Breast Development: Stage 5
Areolar mound recedes into single breast contour with areolar hyperpigmentation, papillae development and nipple protrusion
Age of onset of puberty in boys
9-14
Male Genital Development: Stage 1
Testicular volume < 4 ml or long axis < 2.5 cm
Male Genital Development: Stage 2
4 ml-8 ml (or 2.5-3.3 cm long), 1st pubertal sign in males
Male Genital Development: Stage 3
9 ml-12 ml (or 3.4-4.0 cm long)
Male Genital Development: Stage 4
15-20 ml (or 4.1-4.5 cm long)
Male Genital Development: Stage 5
> 20 ml (or > 4.5 cm long)
Pubic Hair Growth: Stage 1
No hair
Pubic Hair Growth: Stage 2
Downy hair
Pubic Hair Growth: Stage 3
Scant terminal hair
Pubic Hair Growth: Stage 4
Terminal hair fills the entire triangle overlying pubic region
Pubic Hair Growth: Stage 5
Terminal hair extends beyond the inguinal crease onto thighs
What hormones increase to cause growth spurt in puberty? (2)
GH and IGF1
How does a growth spurt occur (regarding bones)?
- Due to proliferation of chondrocytes
- Ends of the long bones
How does the growth spurt end (regarding bones)?
- Terminated by fusion of the epiphyseal plate
What hormone controls the termination of the growth spurt via fusion of the epiphyseal plate?
Oestrogen
Hypothalamic-Pituitary-Gonadal Axis
- Hypothalamus (GnRH)
- Anterior Pituitary (Gonadotrophins/FSH & LH)
- Gonads (Gonadal Hormones/Testosterone/
Progesterone/Oestrogen) - Reproductive Tract
At puberty: GnRH Release is disinhibited, How?
- Kisspeptin, neurokinin B release from KND neurons in
hypothalamus seemed to involved in switching on
GnRH release - Kisspeptin neuropeptide signalling important
- Glutamate signalling also probably involved
- GABA downregulation
Why has age of menarche decreased in the last c.150 years? (3)
- Improved diets etc.
- Improved health/reduced disease
- Possible input of exogenous hormones e.g. in food
Why is Leptin signalling important in puberty?
- Leptin released by fat cells
- Leptin can stimulate GnRH production via kisspeptin
What is critical weight and fat percentage in women for menarche?
- Critical weight of 47kg
- 17% fat
In many species breeding is seasonal- new ‘puberty’ each year, what us this triggered by? What gland and hormone is involved?
- Triggered by changes in day length
- Involvement of pineal gland, source of melatonin
What kind of tumours can influence puberty? (think melatonin)
Pineal tumours
Puberty – Hormonal Events: Females
- Onset of puberty associated with a rise in pulsatile
GnRH secretion - Initially at night
- Followed by a steady rise in FSH & LH secretion
- In girls FSH stimulates follicles, the theca produces
oestrogen
Puberty – Hormonal Events: Males
- Onset of puberty associated with a rise in pulsatile
GnRH secretion - Initially at night
- Followed by a steady rise in FSH & LH secretion
- In boys LH and FSH stimulate testicular enlargement
and testosterone production
What does Idiopathic mean?
Disease with an unknown cause or mechanism of apparent spontaneous origin
What does Pathological mean?
Abnormal anatomical or physiological conditions and objective or subjective manifestations of disease, not classified as disease or syndrome
What is Precocious Puberty?
Puberty in girls before 8 and boys before 9
What is Delayed Puberty in Females?
No sign of breast development by age 13 or breasts present but no menarche by age 15
What is Delayed Puberty in Males?
No sign of testicular development in boys at age 14 (volume <4ml)
What is the Female Climacteric?
It is the period of life starting from the decline in ovarian activity until after the end of ovarian function
What are the Stages in the Female Climacteric?
- Pre-menopause
- Menopause
- Post menopause
When does Pre-Menopause occur?
Typically from age c.40yrs
What happens in Pre-Menopause? (4)
- Follicular phase shortens, ovulation early or
absent - Less oestrogen secreted
- LH & FSH levels rise due to reduced feedback
- Reduced fertility
When does Menopause occur?
c. 45-55 years
What happens in Menopause?
Cessation of menstrual cycles
What happens to sex hormones in Menopause?
- Oestrogen levels fall dramatically
- FSH & LH levels rise, FSH dramatically
Side Effects of Menopause (11)
- Vascular changes i.e., ‘hot flushes’
- Regression of endometrium
- Shrinkage of myometrium
- Thinning of cervix
- Vaginal rugae lost
- Vaginal dryness
- Involution of some breast tissue
- Changes in skin
- Changes in bladder
- Bone mass reduces by 2.5% per year for several years
- Osteoporosis
What happens in Post-Menopause?
- No periods for 12 consecutive months
- Fertility ends (low possibility up and until this stage)
Benefits of Oestrogen for Post-Menopausal Women?
- Relieves symptoms of the menopause
- Can limit osteoporosis
Cons of Oestrogen for Post-Menopausal Women?
- Not advised for cardio-protection
- Not advised/caution if VTE or stroke risk or breast/
ovarian/endometrial cancer risk
The end of reproductive life: Males
- No obvious ‘event’ equivalent to menopause
- But a gradual decline in semen volume, sperm motility,
quantity and quality throughout adult life in males
