Chapter 10- Human Growth and Development

A summary of the 10th Chapter- Human growth and development of the AQA GCSE Human Health and Physiology textbook

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  • Created by: R_Hall
  • Created on: 15-06-12 17:24

10.1 Growth and puberty

  • The rate of growth is fastest as a baby, then slows down and steadies until puberty.
  • The changes ( in body shape, growth, voices, hair, sperm production-boys, and starting menstruation- girls) that happen during puberty are controlled by the sex hormones oestrogen and testosterone
  • Puberty starts when the pituitary gland is stimulated by the hypothalamus to release the hormones FSH and LH. These travel to testes/ovaries which start to secrete testosterone/oestrogen and cause puberty to start
  • The menstrual cycle lasts approximately 28 days, and ovulation occurs in the middle of the cycle
  • Because the cycle is controlled by hormones, the hormone oestrogen in a contraceptive pill can stop the release of an egg
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10.2 Menstrual Cycle

  • There are4 main hormones controlling the menstrual cycle-
  • FSH  (Follicle Stimulating Hormone) is produced by the pituitary gland and it stimulates follicles (egg-containing sacs) to grow and to produce oestrogen
  • LH (Luteinising Hormone) is produced by the pituitary gland and stimulates the release of an egg from a follicle and the development of corpus luteum, formed by follicle cells after ovulation
  • Oestrogen is produced by ovaries and causes the uterus lining to build up before ovulation
  • Progesterone is produced by corpus luteum in ovaries after ovulation and maintains the uterus lining for a fertilised egg
  • Rising oestrogen levels stimulate the release of LH, which stimulates ovulation and progesterone release.
  • If the egg is fertilised, it travels down the oviduct and embeds in the uterus lining. Oestrogen and progesterone continue to maintain the lining until 12 weeks
  • If the egg doesn't implant, oestrogen and progesterone are not produced (and corpus luteum degenerates), and the uterus lining breaks down
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