Life Sciences Term 1

Puberty

• This is a time of life when a person becomes sexually mature
  
• Physical changes occur between 10 and 14 in girls and 12 and 16 for boys
  
• It begins when the hypothalamus in the brain starts releasing gonadotropin-releasing hormone (GnRH)
  

In males

Starts when GnRH stimulates the anterior pituitary gland to secrete:

• Follicle Stimulating Hormone (FSH) – which stimulates the testes to produce sperm
  
• Luteinising hormone (LH) – which stimulates the testes to produce testosterone
  
• Secondary sexual characteristics (caused by testosterone):
  
• Rapid increase in height, size and strength of muscles
• Development and functioning of the prostate gland, seminal vesicles and Cowper’s glands
• Voice deepens
• Hair grows in the pubic area, armpits and on the face
• Testes and penis increase in size

In females

Starts when GnRH stimulates the anterior pituitary gland to secrete:

• Follicle Stimulating Hormone (FSH) – stimulates a follicle in the ovary to develop and secrete oestrogen
  
• Luteinising hormone (LH) – stimulates the development of the corpus luteum in the ovary to secrete progesterone (not responsible for secondary sexual characteristics)
  
• Secondary sexual characteristics (caused by oestrogen):
  
• Rapid increase in height and breast development
• Hair growth in the pubic area and armpits
• Increase in size of the vagina
• Uterine and endometrial growth
• Onset of menstruation
• Increase in body fat