Lecture 4.2: Puberty and the Menopause Flashcards by Purva Shegunshi

What is Puberty? What occurs during it?

Development of reproductive maturity
Secondary sexual characteristics
Gamete production/maturation
Behavioural changes necessary for reproduction

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Tanner Staging: Stage 1

Hormone release begins but no physical changes

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Tanner Staging: Stage 2

First physical changes noticeable
* Girls: breast bud
* Boys: testes and scrotum enlargement

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Tanner Staging: Stage 3

Growth spurts, physical changes progress
* Girls: fat deposits on hips in girls
* Boys: voice cracking and nocturnal ejaculation

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Tanner Staging: Stage 4

Key functional events
* Girls: menarche
* Boys: spermatogenesis

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Tanner Staging: Stage 5

Adult physical appearance and function
* Girls: regular periods and ovulation
* Boys: facial hair and musculature

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Age of onset of puberty in girls

8-13

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What is Adrenarche

Beginning of pubic hair growth

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Breast Development: Stage 1

No glandular breast tissue palpable

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Breast Development: Stage 2

Breast bud palpable under areola (1st pubertal sign in females)

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Breast Development: Stage 3

Breast tissue palpable outside areola; no areolar development

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Breast Development: Stage 4

Areola elevated above contour of the breast, forming “double scoop” appearance

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Breast Development: Stage 5

Areolar mound recedes into single breast contour with areolar hyperpigmentation, papillae development and nipple protrusion

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Age of onset of puberty in boys

9-14

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Male Genital Development: Stage 1

Testicular volume < 4 ml or long axis < 2.5 cm

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Male Genital Development: Stage 2

4 ml-8 ml (or 2.5-3.3 cm long), 1st pubertal sign in males

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Male Genital Development: Stage 3

9 ml-12 ml (or 3.4-4.0 cm long)

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Male Genital Development: Stage 4

15-20 ml (or 4.1-4.5 cm long)

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Male Genital Development: Stage 5

> 20 ml (or > 4.5 cm long)

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Pubic Hair Growth: Stage 1

No hair

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Pubic Hair Growth: Stage 2

Downy hair

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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