3.1: puberty (workbook)

Question 1

when are most primary sexual characteristics developed?

Answer 1

before birth

Question 2

when do hormonal changes occur in the male?

Answer 2

first few months of life

Question 3

when do male and female reproductive systems remain inactive until?

Answer 3

puberty

Question 4

describe the timing of puberty

Answer 4

The timing of puberty varies between the sexes and between individuals

Question 5

how is the sequence of events in puberty like?

Answer 5

a fixed sequence of events

Question 6

do girls or boys reach puberty first?

Answer 6

girls

Question 7

what is the age range of puberty for girls?

Answer 7

8-13 years for girls

Question 8

what is the age range of puberty for boys?

Answer 8

9-14 years for boys

Question 9

what are obvious signs of puberty preceded by?

Answer 9

a series of events that depend upon sex steroids secreted from the gonads and adrenal glands

Question 10

what is the growth spurt?

Answer 10

a marked acceleration of growth in both boys and girls

Question 11

which gender begins growth spurt first?

Answer 11

girls

Question 12

what is the velocity of growth spurt in girls?

Answer 12

about 9cm/year in girls

Question 13

what is the velocity of growth spurt in boys?

Answer 13

about 10cm/year in boys

Question 14

why do adult males end up larger?

Answer 14

boys grow more before the growth spurt and slightly more during it

Question 15

what is the growth spurt terminated by?

Answer 15

epiphyseal fusion, at which point adult height is virtually set

Question 16

what are the main secondary sexual characteristics and what do they develop under?

Answer 16

such as breasts, genitalia and pubic hair

develop under the influence of sex steroids

Question 17

in the female, what stimulates breasts and female genital development?

Answer 17

gonadal oestrogens (from ovaries) influence breast development and female genital development

Question 18

what stimulates pubic and axillary hair development in females?

Answer 18

controlled by androgens from the adrenals (adrenal cortex)

Question 19

what do testicular androgens control in males?

Answer 19

development of genitalia, body hair and deepening of the voice

Question 20

what is first menstrual bleed in girls called?

Answer 20

menarche

a defining event in puberty for girls

Question 21

what is the equivalent of menarche in boys?

Answer 21

occurrence of nocturnal erection and the first ejaculation

which is much less easy to monitor

Question 22

does menarche and nocturnal erection & first ejaculation indicate full fertility?

Answer 22

Neither of the events indicates the onset of full fertility

Question 23

what happens to plasma levels of FSH and LH in girls (after menarche)?

Answer 23

plasma levels of FSH and LH rise gradually from about 7 years of age to reach adult levels at or soon after menarche

Question 24

what happens to plasma oestrogen levels in girls?

Answer 24

Plasma oestrogen levels rise steadily, until at the beginning of menstrual cycles regular cyclical rises and falls are associated with the ovarian cycle

Question 25

what is the anterior pituitary gonadal axis capable of responding to?

Answer 25

stimulation by GnRH long before puberty normally occurs but GnRH secretion is low

Question 26

what is the anterior pituitary gonadal axis capable of responding to before puberty?

Answer 26

stimulation by GnRH long before puberty normally occurs but GnRH secretion is low

Question 27

what is the anterior pituitary gonadal axis capable of responding to before puberty?

Answer 27

stimulation by GnRH long before puberty normally occurs but GnRH secretion is low

Question 28

when does puberty occur?

Answer 28

when the brain initiates pulsatile GnRH secretion

Question 29

when does puberty occur?

Answer 29

when the brain initiates pulsatile GnRH secretion

Question 30

what does brain’s pulsatile GnRH secretion depend on?

Answer 30

This does not seem to depend on any signal from the

gonads

Question 31

how has menarche age changed in girls?

Answer 31

First, puberty has become steadily earlier in western
societies over the past 150 years.
In 1830 girls reached menarche at 17 years of age,
now it occurs at an average, age 13.

Question 32

how has menarche age changed in girls?

Answer 32

First, puberty has become steadily earlier in western
societies over the past 150 years.
In 1830 girls reached menarche at 17 years of age,
now it occurs at an average, age 13.

Question 33

The main determining factor influencing puberty?

Answer 33

body weight

Question 34

what is the body weight at menarche?

Answer 34

about 47kg

Question 35

what is the body weight at the beginning of growth spurt (in girls)?

Answer 35

30kg

Question 36

what is the critical weight in boys?

Answer 36

55kg

Question 37

what may indicate to the hypothalamus the attainment of the initial body weight?

Answer 37

plasma concentration of a fat derived hormone – leptin

Question 38

in many species (where breeding is seasonal), what is GnRH secretion switched on and off by? reflected in?

Answer 38

by changes in daylight, influencing the pineal gland

and reflected in changes in the secretion of melatonin.

Question 39

what can precocious and delayed puberty in humans be associated with?

Answer 39

various CNS disorders such as meningitis and tumours