Endocrine: Sex Development, Growth and Puberty

Question 1

What hormonal changes occur at puberty?

Answer 1

1) Increased of GnRH and GHRH
2) Increased levels of FSH, LH and sex steroids
3) Increased levels of growth hormone

Question 2

What factors can influence puberty?

Answer 2

Nutrition (BMI), Leptin/Insulin, Genetics, Exercise and Socio-cultural

Question 3

What factors affect growth hormone secretion?

Answer 3

Starvation, Exercise, Trauma, Hypoglaecemia, Deep Sleep

Question 4

If problem with growth hormone secretion then what problems present?

Answer 4

Gigantism, Dwarfism, Acromegaly

Question 5

What happens in the Hypothalamo-pituitary-testicular axis

Answer 5

1) GnRH from hypothalamus acts on the APG to release LH/FSH
2) LH acts on Leydig to stimulate testosterone, FSH on sertoli to cause inhibin release
3) Inhibin/Testosterone have negative feedback effect on hypothalamus and anterior pituitary

Question 6

What happens in the Hypothalamo-pituitary-ovarian axis?

Answer 6

1) GnRH from hypothalamus acts on APG to release LH/FSH
2) LH acts on theca cells to stimulate androgen release which diffuses from theca to granulosa
3) FSH acts on granulosa stimulating conversion of androgen into oestrogen
4) Inhibin released from granulosa w/ Oestrogen has negative FBL on hypothalamus and APG

Question 7

What is the function of dihydrotestosterone?

Answer 7

Stimulation of differentiation of male external genitalia, secreted by the testis

Question 8

How is growth hormone secreted?

Answer 8

Pulsatile fashion and increases during deep sleep

Question 9

What happens in the GH/IGF-1 axis?

Answer 9

1) Hypothalamus releases GHRH (+) or SMS (-)
2) APG releases GH which acts on liver causing IGF-1 to be produced
(-VE FBL on hypothalamus)

Question 10

What role does IGF-1 have?

Answer 10

Induces cell division

Question 11

What cells is GH synthesised in?

Answer 11

Somatotroph Cells (40-50% of APG)
[Most abundant in APG]

Question 12

What are the definitive signs of puberty in female?

Answer 12

Girls: Menarche

a) Ovarian Oestrogen: Breast and Female Gen
b) Ovarian/Adrenal Androgen: Control pubic and axillary hair

Question 13

What are the definitive signs of puberty in males?

Answer 13

Boys: First ejaculation (Nocturnal and don’t notice)
a) Testicular Androgens: External genitalia and pubic hair growth
Enlargement of larynx and laryngeal muscles