growth and development 1 puberty viv rolfe. discuss the age of onset of puberty in males and females...
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Growth and Development 1
PUBERTY
Viv Rolfe
• Discuss the age of onset of puberty in males and females
• Development of secondary sexual characteristics at puberty
• Identify the roles of hormones in puberty
Lecture Content
What is Puberty?
•Period of growth and sexual maturitymarking the transition from child to adult.
•Maturation of the secondary sexual characteristics.
How old are girls and boyswhen this typically
happens?
Girls
Stop
Child
Adolescence
AdultEarly Late
Age 10 11 12 13 14 15 16 17 18 19 20
Period of Puberty
Girls Boys
Stop Stop
Child
Adolescence
AdultEarly Late
Age 10 11 12 13 14 15 16 17 18 19 20
Period of Puberty
Physiological ChangesVoice breaks
Body hair
Wet dreams
Behavioural changes
Spots
Sweat
Sperm production
Skeletal growth and muscle
Testicles dropping?
Growth – skeletal, muscle, fat
Menstrual cycle – periods
Breast development
Body hair
Sweat and spots
Voice deepening
Mood swings
Development of Secondary Sexual Characteristics(Tanner’s Stages, 1978)
Stage I Pre-adolescent
Stage II First signs of puberty
Stage III Intermediate stage
Stage IV Intermediate stage
Stage V Adult characteristics
Girls Pubertal Changes
Breast Stage 2
Pubic hair Stage 2 Pubic hair Stage 5
Breast Stage 4Menarche
AGE 8 9 10 11 12 13 14 15 16 17
Boys Pubertal Changes
AGE 8 9 10 11 12 13 14 15 16 17
Genital Stage 2
Genital Stage 4
Pubic hair Stage 2
Pubic hair Stage 5
0
5
10
15
20
25
Age (years)
Hei
ght
gain
(cm
/ y
ear)
Boys
Girls
Rate of change of Height gain
Sources: Malina, 1990, Tanner, 1990, Lindsay et al, 1994, Baumgartner et al, 1986 (cited in Bee, 2000)
Puberty is happening at a much earlier agethese days. Why???
What Hormones Trigger Puberty in Girls?
SIMPSON, H.
Source: Aha! Jokes, http://www.AhaJokes.com/ © www.nlm.nih.gov (National Library of Medicine)
Hypothalamus
Pituitary
Pituitary Gland
GONADOTROPHINRELEASING HORMONE
GnRH
FOLLICLE STIMULATING HORMONELUTEINISING HORMONE
OVARIES RELEASEPROGESTERONE
OESTROGEN
INITIATESPUBERTY
PREPARES BODYFOR PREGNANCY
FSHLH
0
10
20
30
40
50
60
70
80
9 10 11 12 13 14
Age (years)
Oes
trag
en l
evel
s(p
g/1
ml)
Boys
Girls
Changes in Oestragen levels
EstrogensProduced by Graafian follicles or the placenta
Stimulates the development of secondary female characteristics
Matures female reproductive organs
Helps prepare the uterus to receive a fertilized egg and maintain pregnancy.
Hormones of the Ovaries
Progesterone
Produced by the corpus luteum
Acts with estrogen to bring about the menstrual cycle
Helps in the implantation of an embryo in the uterus.
Hormones of the Ovaries
What Hormones Trigger Puberty in Boys?
GONADOTROPHIN
FOLLICLE STIMULATING HORMONELUTEINISING HORMONE
FSHLH
TESTESRELEASE
TESTOSTERONE
INITIATESPUBERTY
0
50
100
150
200
250
300
350
400
9 10 11 12 13 14
Age (years)
Tes
tost
ero
ne
leve
ls(n
g/1
ml)
Changes in testosterone levels
Interstitial cells of testes are hormone-producing
Produce several androgens
Testosterone is the most important androgenResponsible for adult male secondary sex characteristics
Promotes growth and maturation of male reproductive system
Required for sperm cell production
Hormones of the Testes
These hormones surge round the bodycompletely changing it.
How long puberty takes varies betweenindividuals.