3.1 lecture: endocrinology 'Puberty and Menopause'

Question 1

what is Thelarche?

Answer 1

development of breast

Question 2

what is Puberache?

Answer 2

development of axillary & pubic hair

Question 3

what is Menarche?

Answer 3

the first menstrual period

Question 4

what is Adrenarche?

Answer 4

the onset of an increase in the secretion of androgens

Question 5

what is puberty?

Answer 5

A stage of human development when sexual maturation and growth are completed and result in ability to reproduce

Question 6

what happens during puberty?

Answer 6

– Accelerated somatic growth
– Maturation of primary sexual characteristics (gonads and genitals)
– Appearance of secondary sexual characteristics (pubic and axillary hair, female breast development, male voice changes,…)
– Menstruation and spermatogenesis begin

Question 7

which organ initiates puberty?

Answer 7

brain

Question 8

what is onset of puberty associated with? why?

Answer 8

steady increase in FSH and LH

due to increase in GnRH secretion

Question 9

when can most parts of reproductive system work before?

Answer 9

Most parts of the reproductive system can work before normal age of puberty

Question 10

why does the reproductive system not function before the normal age of puberty?

Answer 10

because hormone levels are low

due to low GnRH (from hypothalamus - brain initiates puberty)

Question 11

what does growth spurt depend upon?

Answer 11

Depends on growth hormone and steroids in both sexes

Question 12

why are men taller?

Answer 12

Men larger because growth spurt longer and slightly faster (10cm instead of about 9cm/year)

Question 13

what does Genital development in boys depend upon?

Answer 13

testosterone

Question 14

when does growth spurt occur in girls compared to boys?

Answer 14

earlier and shorter in girls

Question 15

what marks the end of growth spurt in both genders?

Answer 15

closing of epiphyseal growth plates (epiphyseal fusion)

Question 16

why do girls growth spurt end earlier?

Answer 16

Oestrogen closes epiphyses earlier in girls

Question 17

what happens to girls if there is a significant weight loss?

Answer 17

reproductive cycles cease

Question 18

what is one of the contributing factors of puberty?

Answer 18

nutrition
(especially earlier puberty)
(living conditions, healthcare)

Question 19

what is the most important contributing factor of puberty?

Answer 19

body weight (girls: 47kg before menarche, boys: 55kg)

Question 20

what may be involved in signalling for initiation of puberty?

Answer 20

leptin (fat hormone)

Question 21

what is a factor associated with delayer menarche?

Answer 21

malnutrition

Question 22

what is primary amenorrhea common in?

Answer 22

lean female athletes

Question 23

what is ‘body fat’ set point very noticeable in?

Answer 23

girls with fluctuating body weight due to anorexia nervosa

Question 24

in mammals breeding seasonally, what is puberty each year associated with?

Answer 24

– Triggered by changes in day length
– Involvement of pineal gland
– Secretion of melatonin

Question 25

which tumour can influence puberty in humans?

Answer 25

pineal tumours

Question 26

what does puberty hormonal changes precede in humans?

Answer 26

physical changes

Question 27

what do the puberty hormonal changes cause in humans?

Answer 27

Increased stimulation of hypothalamo-pituitary-gonadal | axis (HPG) - from hypothalamus increasing GnRH pulses

Question 28

what are the puberty hormonal changes? (HPG axis)

Answer 28

– gradual activation of the GnRH – increases frequency and amplitude of LH pulses (from increase GnRH) – gonadotropins (FSH/LH) stimulate secretion of sexual steroids (oestrogenes and androgenes)

Question 29

what are the extragonadal hormonal changes associated with puberty hormonal changes (HPG axis)

Answer 29

elevation of IGF-I, | and adrenal steroids

Question 30

what does GH secretion from pituitary cause?

Answer 30

* Increases TSH * increases metabolic rate * promotes tissue growth * increase androgens = retention of minerals in body to support bone and muscle growth

Question 31

what does GH secretion from pituitary result in?

Answer 31

growth spurt

Question 32

what does GH secretion from pituitary cause (hormones / metab)?

Answer 32

* Increases TSH (so more T3/T4) * increases metabolic rate * promotes tissue growth * increase androgens (oestrogen/testosterone) = retention of minerals in body to support bone and muscle growth

Question 33

what does GH secretion from pituitary result in?

Answer 33

growth spurt

Question 34

what are the first phenotypic changes in females puberty?

Answer 34

breast development

Question 35

what are the first phenotypic changes in males puberty?

Answer 35

testicular enlargement

Question 36

what precedes phenotypic changes by several years?

Answer 36

Nocturnal GnRH pulsatility (LH secretion)

Question 37

what does sleep dependent nocturnal rise in LH suggests in adolescent boys? (HPG axis)

Answer 37

in adolescent boys, the sleep related LH (AP) increases | stimulating a nocturnal rise of testosterone (gonads)

Question 38

what does the nocturnal rise in testosterone stimulated by LH account for?

Answer 38

some of the early pubertal changes seen in males

Question 39

what is the similar pattern of early pubertal changes seen in females stimulated by?

Answer 39

concomitant increase in oestrogen

Question 40

at which age do blood levels of LH,FSH increase? how?

Answer 40

9-12 years | amplitude of pulses increase, especially during sleep

Question 41

what does high blood levels of LG, FSH lead to between 9-12 years?

Answer 41

initiate gonadal development | young children, LH + FSH levels insufficient to initiate gonadal function

Question 42

when do FSH and LH increase in males? leading to?

Answer 42

LH + FSH increase at about 10 years | spermatogenesis, androgen secretion from adrenals

Question 43

what does androgens released from adrenal glands initiate in males?

Answer 43

growth of sex accessory structures (e.g. prostate) | male secondary sex characteristics (facial hair, growth of larynx - voice breaks)

Question 44

what induces secondary sex characteristics in females?

Answer 44

oestrogen

Question 45

what are the secondary sex characteristics in females?

Answer 45

growth of pelvis (more lateral acetabulum) deposit of subcutaneous fat maturation of internal reproductive organs development of external genitalia

Question 46

what does androgens released by adrenal glands in female cause?

Answer 46

growth of pubic hair growth of bone increased secretion from sebaceous glands