3.1 lecture: endocrinology (part 2)

Question 1

what is pubertal development classified according to?

Answer 1

Tanner standard

Question 2

how many stages are there in the tanner standard?

Answer 2

5 different stages

Question 3

what are the features which fall under the 5 tanner stages within girls?

Answer 3

breast (B1-5)
pubic hair (Pu1-5)
axillary hair (A1-5)
menarche

Question 4

what are the features which fall under the 5 tanner stages within boys?

Answer 4

testicular volume > 4ml (Te)
penis enlargement (G1-5)
pubic hair (Pu1-5)
axillary hair (A1-5)
spermarche (nocturnal erection, first ejaculation - LH/FSH)

Question 5

describe the pubertal growth (rate)

Answer 5

growth velocity is 2-3 times > prepubertal

sexual dimorfism in pubertal growth (sexual organs develop)

Question 6

what is the age range of puberty in girls?

Answer 6

9-13 years

Question 7

what happens during puberty in girls?

Answer 7

breast bud (thelarche) --> adult breasts
pubic hair growth --> pubic hair adult
begins adrenarche (adrenal androgen secretion) 
growth spurt
onset of menstrual - menarche (cycles)

Question 8

what is the sequence of puberty development in girls?

Answer 8

height spurt –> breasts –> pubic hair

menarche at around peak height spurt (47kg)

Question 9

what is the age range of puberty in boys?

Answer 9

10-14 years

Question 10

what happens during puberty in boys?

Answer 10

genital development –> adult genitalia
pubic hair growth –> adult pubic hair
spermatogenesis
growth spurt

Question 11

what is the sequence of puberty development in boys?

Answer 11

testicular volume –> genitalia size –> height spurt (same time as pubic hair)

Question 12

what is the first sign of puberty in boys?

Answer 12

testicular volume up to 4ml (G2)

Question 13

what is the first sign of puberty in girls?

Answer 13

B2 (breast bud development)

Question 14

what is the growth velocity of boys? during when?

Answer 14

10.3cm/year (Tanner III-IV)

Question 15

what is the growth velocity of girls? during when?

Answer 15

9cm/year (Tanner II-III)

Question 16

what is the duration of puberty in boys? when does it end?

Answer 16

3.2 +/- 1.8 yrs

ends when adult size of testis

Question 17

what is the duration of puberty in girls? when does it end?

Answer 17

2.4 +/- 1.1

ends at menarche

Question 18

what initiates menarche in girls?

Answer 18

LH surge initiates 1st ovarian cycle

Question 19

what are the hormonal changes surrounding menarche in girls?

Answer 19

LH surge usually not sufficient to cause ovulation during 1st cycle
brain + endocrine (adrenals) systems mature soon after
oestrogen levels in blood increase (from growing follicles)

Question 20

what are the hormones like at the beginning of menarche? (HPG)

Answer 20

corpus luteum absent (low progesterone)
follicles only part developed (little oestrogen + inhibin)
little inhibition at hypothalamus / pituitary (little oestrogen from gonad follicles)
FSH increase (from increase GnRH, no inhibition)

Question 21

what are the hormones like during mid-follicular phase of menarche?

Answer 21

oestrogen levels rising (developing follicle)
inhibin levels rising (selective inhibition of FSH, therefore no new follicles can develop)
oestrogen (high levels) exerts positive feedback on hypothalamus and pituitary
LH rise (to LH surge)

Question 22

what happens during ovulation (affected by)?

Answer 22

precise timing of LH surge

therefore ovulation affected by environment

Question 23

what are the hormonal changes after ovulation?

Answer 23

corpus luteum forms spontaneously
begins to secrete progesterone and oestrogen
maintains suppression of FSH (oestrogen negative feedback)
LH suppressed (progesterone feedback inhibition)

Question 24

what happens to cause the start of a new cycle?

Answer 24

death of corpus luteum –> rapid fall in progesterone + oestrogen (steroid levels)
low P+O = stimulates menses (shedding of endometrial lining)
low P+O relieves inhibition on FSH (cycle begins again - follicle stimulated to develop –> oestrogen)