Repro 3.1 Puberty and Menopause Flashcards Preview

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Flashcards in Repro 3.1 Puberty and Menopause Deck (44)
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1

When are primary sexual characteristics established?

Before birth

2

When do male and female reproductive systems become active?

Puberty

3

When do male hormone levels change?

First few months of life

4

At what age do girls and boys reach puberty?

Girls - 8-13
Boys - 9-14

5

From where are sex steroids secreted?

Adrenal glands and gonads

6

Why do boys grow taller?

Growth spurt starts later so they have grown more before it starts and grow at a faster rate during the growth spurt and it is also slightly longer (10cm/year as opposed to 9cm/year in girls)

7

What terminates the growth spurt?

Epiphyseal fusion - adult height virtually set

8

What controls the development of secondary sexual characteristics in girls?

Gonadal oestrogens influence breast development and female genital development
Androgens from adrenals control the development of pubic and axillary hair

9

What controls the development of secondary sexual characteristics in boys?

Testicular androgens control the development of genitalia and body hair and deepening of the voice

10

What is the name for the onset of a girls first menstrual bleed?

Menarche

NB. This does not indicate the onset of full fertility

11

What is the equivalent event for boys to menarche in girls?

Nocturnal erection and first ejaculation (more difficult o monitor)

NB. This does not indicate the onset of full fertility

12

Describe the hormonal changes in a girl until menarche.

Plasma levels of FSH and LH rise gradually from about 7 years of age to reach adult levels at of soon after menarche.
Plasma oestrogen levels rise steadily until at the beginning of menstrual cycles regular cyclical rises and falls are associated with the ovarian cycle
Weak androgens are secreted from adrenal glands

13

Describe the hormonal changes in boys from birth to adult level.

FSH and LH rise later than girls to reach adult levels around 16 years of age. This is associated with a steady rise in testosterone levels
Weak androgens are secreted from adrenal glands

14

What changes in the body signal the onset of puberty?

The brain initiates pulsatile GnRH secretion. This does not seem to depend on any signal from the gonads

15

What are the 2 theories explaining the onset of puberty?

Decreasing hypothalamic sensitivity to feedback -> Increased GnRH secretion
Hypothalamic mechanisms mature and steadily secrete more GnRH under other influences

16

Why has the onset of puberty become steadily earlier in the last 150 years in western society?

The main determining factor for onset of puberty is weight. Increased average body mass has decreased the age at which the onset of puberty occurs

17

Approximately what is the body weight at menarche?

47kg

18

What is the approximate weight of the growth spurt in girls?

30kg

19

What is the critical weight for boys for the onset of the growth spurt?

55kg

20

How is the hypothalamus aware of the appropriate weight for onset of puberty is achieved?

Leptin, a fat derived hormone may indicate to the hypothalamus the attainment of the body weight

21

What are some causes of precocious puberty?

Central:
-Meningitis/trauma (inflammation)
-tumours of the brain or spinal cord

Peripheral:
-Tumours of the gonads
-Exposure to external sources of oestrogen and progesterone

22

In order, what are the stages of puberty in girls?

1) Breast bud appears (thelarche)
2) Pubic hair growth begins (adenarche)
3) Growth spurt
4) Onset of menstruation (menarche)
5) Adult pubic hair
6) Adult breasts

23

In oder, what are the stages of puberty in a boy?

1) Genital development begins
2) Pubic hair growth (adenarche)
3) Spermatogenesis begins
4) Growth spurt
5) Genitalia of adult
6) Pubic hair of adult

24

Define precocious puberty.

Physical signs of sexual maturation before 8 years or menarche before 10 years old.

25

What is true precocious puberty?

Precocious puberty caused by premature secretion of gonadotrophins. Usually idiopathic but can be caused by CNS lesions.

26

What is the effect of precocious puberty on height?

Shorter - growth spurt begins and terminates earlier. Oestrogen closes epiphyseal growth plates

27

How would you assess a boys stage in puberty?

Height
Weight
Genital size
Body hair
Bone age
Medical history

28

Define delayed puberty

Lack of sexual maturation by age 15 - majority constitutional delay (benign)

29

What proportion of 14 year old boys would be expected to not yet be exhibiting signs of puberty?

3-5% - visibly begins aged 9-14

30

What is bone age and what might it indicate in delayed puberty?

Age suggested by bone - density, presence of epiphyseal growth plates etc.
Young bone age may indicate delayed puberty
Normal bone age may indicate there is a problem causing the delayed puberty