6.6  Hormones, Homeostasis and Reproduction

big ninja

Essential Idea:

Hormones are used when

signals need to be widely distributed


  • Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration
  • Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature
  • Leptin is secreted by cells in adipose tissue and act on the hypothalamus of the brain to inhibit appetite
  • Melatonin is secreted by the pineal gland to control circadian rhythms
  • A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone
  • Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty
  • Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty
  • The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones


  • Causes and treatment of Type I and Type II diabetes
  • Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease
  • Causes of jet lag and use of melatonin to alleviate it
  • The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy
  • William Harvey’s investigation of sexual reproduction in deer


  • Annotate diagrams of the male and female reproductive system to show names of structures and their functions