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 maturity marking the transition from child to adult. Maturation of the secondary sexual characteristics.

How old are girls and boys when this typically happens?

Girls Stop Child Adolescence Adult Early Late Age Period of Puberty

GirlsBoys Stop Child Adolescence Adult Early Late Age Period of Puberty

Physiological Changes Voice 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 IPre-adolescent Stage IIFirst signs of puberty Stage IIIIntermediate stage Stage IVIntermediate stage Stage VAdult characteristics

Girls Pubertal Changes Breast Stage 2 Pubic hair Stage 2 Pubic hair Stage 5 Breast Stage 4 Menarche AGE

Boys Pubertal Changes AGE Genital Stage 2 Genital Stage 4 Pubic hair Stage 2 Pubic hair Stage 5

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 age these days. Why???

What Hormones Trigger Puberty in Girls?

SIMPSON, H. Source: Aha! Jokes, © (National Library of Medicine) Hypothalamus Pituitary Pituitary Gland

GONADOTROPHIN RELEASING HORMONE GnRH FOLLICLE STIMULATING HORMONE LUTEINISING HORMONE

OVARIES RELEASE PROGESTERONE OESTROGEN INITIATES PUBERTY PREPARES BODY FOR PREGNANCY FSH LH

Age (years) Oestragen levels (pg/1ml) Boys Girls Changes in Oestragen levels

 Estrogens  Produced 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 HORMONE LUTEINISING HORMONE

FSH LH TESTES RELEASE TESTOSTERONE INITIATES PUBERTY

Age (years) Testosterone levels (ng/1ml) Changes in testosterone levels

 Interstitial cells of testes are hormone- producing  Produce several androgens  Testosterone is the most important androgen  Responsible 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 body completely changing it. How long puberty takes varies between individuals.