1.5 Individual human development during youth: Physical

Physical Development

Primary and Secondary Sex Characteristics

• Primary sex characteristics are those change that are directly involved in REPRODUCTION – these will involve enlargement of sex organs eg: penis and vagina

• Secondary sex characteristics are not directly required for reproduction. So they will involve all the other changes that occur during puberty eg: widening of shoulders, pubic hair, oily skin, breast development.

Primary & Secondary sex characteristics

SIMILARITIES• Pubic hair• Oily skin• Voice

deepens• Acne• Increase in

height• Increase in

body odour

FEMALESPrimary sex characteristicsIncrease in size of vagina & uterusOvaries produce hormones to start the menstrual cycleSecondary sex characteristicsHips widenDevelopment of breastsDistribution of fat to hipsBody gets curvier

MALESPrimary sex characteristicsGrowth of scrotum & testesSecretion of hormones related to sperm productionGrowth of penis2ndry sex characteristicsBody & facial hairMore muscle massGreater height than femalesBroadening shoulders

Hormone Gland that secretes it / them

Role it plays in physical development during puberty

Follicle Stimulating Hormone (FSH)&Lutenising Hormone (LH)

Pituitary gland (in brain)

Act on the testes and ovaries to release testosterone or oestrogen

Testosterone Testes (testicles) Responsible for the development of male sex characteristics, muscle growth, hair growth and voice changes

Oestrogen Ovaries Responsible for the development of female sex characteristics, breast development and the regulation of the menstrual cycle.

Growth Hormone (GH)

Pituitary Gland Increases the rate of growth

Thyroxine Thyroid Gland Regulates metabolism, which is required to produce the extra energy needed for the changes that occur to the body during puberty.

Hormone actions on the female body

• For females:

• For males:GnRH is released from

the brain

FSH and LH are released from the pituitary gland

(brain)

LH and FSH act on the ovaries

Oestrogen is released from the ovaries which results in

female characteristics developing

Hormone actions on the male body

GnRH is released from the brainFSH and LH are released from the pituitary gland

(brain)

LH and FSH act on the testesTestosterone is released from the testes which results in the male

characteristics developing