Lecture 27: puberty

Question 1

Puberty is? and is caused by?

Answer 1

• Secondary sex characteristics appear and mature
• Adolescent growth spurt occurs
• Fertility is achieved
• Profound psychological effects are observed

Result from:

• Maturation of the HPG axis
• stimulation of the sex organs
• secretions of sex seroids

Question 2

First signs?

Answer 2

Occurs over 3-4 years and starts as the gonadostat ‘turns off’ but in

Girls = Breast development @ 9.5-10 years with early being < 8y

Boys = increased testicular size >3mL @ 11.5-12

Question 3

Thelarche

Pubarche

Gonadarche

adrenache

Menarche

gynaecomastia

?

Answer 3

Thelarche - breast development

Pubarche - Pubic hair development

Gonadarche - Gonadal development

adrenache - adrenal production

Menarche - First menstrual period

gynaecomastia - Breast development in boys

Question 4

Genital Development? Pubic hair development? - male

Answer 4

PENIS DEVELOPMENT

1. pre-adolsecent
2. Enlargement of the scrotum and testes (little or penis enlargement)
3. enlargement of penis, mostly length first. further growth of scrotum and testes
4. increased breadth of penis and develoment of glans
5. adult

PUBIC HAIR

1. pre-adolescent
2. slight growth of long, slightly curly hair
3. considerably darker and more curled
4. adult hair type but over a smaller area
5. Spread to medial adpect of the leg - adult

Question 5

Breast development stages?

Answer 5

Tanner stage

1. elevation of the breast and papilla
2. Further elevation and areola but no separation of contours
3. Areola and papilla form a secondary mound above the level of the breast
4. Areola recesses to the general contour of the breast

PUBIC HAIR is basicall the same as males

Question 6

HPA axis for puberty?

Answer 6

Median preoptic nucleus in the hypothalamus signals to the anterior pituitary to release LH and FSH

Question 7

Female feedback loop?

Answer 7

Question 8

Male feedback looP?

Answer 8

Question 9

LH and FSH release in puberty?

Answer 9

early

• tonic phase increases
• night pulses begin

Mid-puberty

• Greater increase in tonic phase
• higher amplitude night pulses

Late-puberty

• day and night pulses

Question 10

Childhood puberty transiton?

Answer 10

• Gonadostat is turned off
• Increased PULSATILE GnRH and thus LH/FSH
• Incrased sex steriod
• reduced negative feedback to sex steroids

Question 11

Gonadostat?

Answer 11

Intrinsic CNS inhibitory mechanism

Sex steroid dependent

GABA appears to be a potent inhibitor of pulsatile GNRH release

Question 12

Kisspeptin?

Answer 12

Product of KISS1 gene, the naturally occuring ligand for GPR54

Kisspeptin expressing neurons are located in the Arcuate, periventricular and preoptic nucleus

Kisspeptin neurons send projections to the preoptic nuclus (GnRH cell bodies)

• GPR45 inactivation leads to failure to go into puberty
• KISS1 and GPR45 expression increased at the start of puberty

Question 13

Inhibin?

Answer 13

Stimulated by FSH and provides negative feedback to FSH

produced by: sertoli cells (M) and Granulosa cells (f)

Question 14

Adrenache?

Answer 14

Increase in adrenal androgen production occuring late in childhood (8-10years)

Temporal association with puberty, NOT a sign of puberty

Produces pubarche (pubic hair development) - NOT A SIGN OF PUBERTY IN GIRLS

‘unknown trigger’

Question 15

Leptin and puberty?

Answer 15

An adipostatic hormone increasing due to increased fat mass

Is a apetite supressant and may be involved with the signalling of puberty (obese children onset earlier) - 1kg lowers menache by 13 days

Question 16

Body composition and puberty?

Answer 16

Lean mass, skeletal mass - Males 1.5x > females

Fat: males truncal, females generalised

Increased bone mineral density in puberty with peak bone mass achieved in early 20s