Puberty

Question 1

What is puberty?

Answer 1

The transition phase that take a person from being a sexually immature child to a sexually mature, reproductively fertile adult

Question 2

What is the definitive sign of puberty in females?

Answer 2

Menarche

Question 3

What is menarche?

Answer 3

First period

Question 4

What is the definitive sign of puberty in males?

Answer 4

First ejaculation (often nocturnal)

Question 5

What is the main feature of the first few menstrual periods?

Answer 5

Anovulatory

Question 6

What is the main feature of the first ejaculations?

Answer 6

Small quantities of seminal plasma

No spermatozoa

Question 7

What causes the 10cm mean height difference between men and women?

Answer 7

Boys have their growth spurt later so are taller at point of take-off

Question 8

Why is average strength of adult men greater?

Answer 8

Greater number of muscle cells due to androgens

Question 9

When is the first ovulation?

Answer 9

Some months - two years after menarche

Question 10

What causes spontaneous erections?

Answer 10

Stressful or emotionally-charged stimuli

Often not sexual matters

Question 11

What do ovarian oestrogens cause?

Answer 11

Growth of breasts and female genitalia

Question 12

What do ovarian and adrenal androgens do?

Answer 12

Growth of female pubic and axillary hair

Question 13

What do testicular androgens do?

Answer 13

Development of male genitalia and body hair

Enlarging of larynx and laryngeal muscles

Question 14

How many ovarian follicles are there in the newborn?

Answer 14

~500,000

Question 15

How many follicles remain at puberty?

Answer 15

~83,000

Question 16

At what stage of development do testes descend from the abdominal cavity?

Answer 16

7th or 8th month of fetal life

Question 17

What controls descent of testes?

Answer 17

MIS and testosterone

Question 18

What is the gubernaculum?

Answer 18

Ligament attached to testes and scrotum that pulls testes down

Question 19

At what age does spermatogenesis begin?

Answer 19

9 years

Question 20

At what age are mature spermatogonia produced?

Answer 20

14/15 years

Question 21

What is cryptorchidism?

Answer 21

Testes that fail to descend

3-4% fail to descend by birth

0. 8% fail to descend by 1 year
1. 3% fail to descend by onset of spermatogenesis

Question 22

How is cryptorchidism treated?

Answer 22

1. Surgery

2. Treatment with gonadotrophins or GnRH to cause descent before damage is done

Question 23

How do gonadotrophin levels change in life?

Answer 23

LH and FSH pulses in first 20 weeks are the same as in adult life

Secretion then ceases and levels are low during childhood

First change is rise in FSH

Then increasingly pulsatile LH

Question 24

How do hormone levels change at menarche?

Answer 24

Sudden surge of LH and FSH sufficient for menstruation but not ovulation

Question 25

What type of hormone pulses are needed for puberty to occur?

Answer 25

LH pulses every 1 to 3 hours at relatively high amplitude

Question 26

Where is oestradiol released from?

Answer 26

Large growing follicles in ovary

Question 27

Where is oestrone released from?

Answer 27

Body fat

Question 28

What kind of androgens are released from the adrenal gland?

Answer 28

Weak androgens to maintain low circulating androgen level Converted to testosterone at target tissues

Question 29

What is the first endocrine change in puberty?

Answer 29

Rise in DHEA Adrenarche

Question 30

What is the source of oestrogens in males?

Answer 30

Sertoli cells

Question 31

What is gynaecomastia?

Answer 31

Slight growth of mammary glands in males Usually goes away within two years

Question 32

What causes acne?

Answer 32

Androgens increase secretions of sebum from sebaceous glands Glands become clogged and infected

Question 33

What are the treatments for acne?

Answer 33

1. Antibiotics 2. Salicylic acid 3. Oral contraceptive 4. Benzoyl peroxide

Question 34

What is the role of growth hormone?

Answer 34

Growth of long bones and tissues Major effect on protein synthesis and glucose homeostasis

Question 35

What is the role of thyroid hormones?

Answer 35

Rise in metabolic rate in both sexes Essential for body growth

Question 36

What causes childhood suppression of sexual maturation?

Answer 36

Androgens/oestrogens exert negative feedback Hypothalamus very sensitive to steroidal inhibition during childhood Sensitivity of hypothalamus decreases as puberty approaches Central inhibition of GnRH pulse generator

Question 37

What does TAC3 code for?

Answer 37

Neurokinin B

Question 38

What is TACR?

Answer 38

TAC3 receptor

Question 39

What is neurokinin B

Answer 39

Member of substance B-related tachykinin family Highly expressed in hypothalamic neurons that also express kisspeptin

Question 40

What is kisspeptin?

Answer 40

Regulator of GnRH secretion

Question 41

At what weight does puberty begin?

Answer 41

47kg in girls 55kg in boys

Question 42

How is weight sensed?

Answer 42

Leptin Receptors in hypothalamus

Question 43

What inhibits reproductive function?

Answer 43

Melatonin Pineal gland secretions

Question 44

What is the result of sensory deprivation on puberty?

Answer 44

Acceleration of sexual maturity

Question 45

What is the effect of excess stress and parental conflict in girls?

Answer 45

Passed through puberty more rapidly Earlier puberty onset

Question 46

What are xeno-oestrogens?

Answer 46

Chemicals in industrial synthesis of plastics that mimic oestrogens

Question 47

What is the effect of altitude on puberty?

Answer 47

Every 100m increase in altitude delays puberty by 3 months

Question 48

What is the effect of CYP3A4 gene?

Answer 48

Produces liver enzyme that degrades testosterone, increasing oestrogen ratio Homozygous leads to breast development before age 9.5 in 90% Heterozygous - 56% No copies - 40%