6.6: Hormones, homeostasis and reproduction

prior learning & retrieval practice

Essential idea: Hormones are used when signals need to be widely distributed.

Exercise 1: Think back to the characteristics of living things (topic 1.1) - what is homeostasis?

A1: Causes and treatment of Type I and Type II diabetes.

Exercise 2: Distinguish between Type I and Type II diabetes - what causes them and how are they treated?

U1: Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.

Exercise 3: Explain the control of blood glucose using a diagram.

U2: Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.

Exercise 4: State where thyroxin is produced and outline its role in the body

U3: Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.

Exercise 5: Outline the role of leptin in suppressing appetite

A2: Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.

Exercise 6: Discuss why using leptin injections to treat obesity does not always work.

A3: Causes of jet lag and use of melatonin to alleviate it.

Exercise 7: Outline the causes of jet lag.

U4: Melatonin is secreted by the pineal gland to control circadian rhythms.

Exercise 8: State where melatonin is produced and outline its action.

A5: William Harvey’s investigation of sexual reproduction in deer.

NoS: Developments in scientific research follow improvements in apparatus—William Harvey was hampered in his observational research into reproduction by lack of equipment. The microscope was invented 17 years after his death. (1.8)

Exercise 9: Outline William Harvey's investigation of sexual reproduction in deer. What did he conclude? Was he correct?

U5: A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.

U6: Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.

Exercise 10: Outline the role of testosterone and list primary as well as secondary sexual characteristics in males and females.

U7: Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.

Exercise 11: Outline the roles of progesterone and estrogen in human development.

U8: The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.

Exercise 12: Describe the menstrual cycle and the role of negative and positive feedback.

S1: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.

Exercise 13: Annotate the following diagrams.

A4: 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.

Exercise 14: Describe the process of IVF.

Guidance from the syllabus: The roles of FSH, LH, estrogen and progesterone in the menstrual cycle are expected. William Harvey failed to solve the mystery of sexual reproduction because effective microscopes were not available when he was working, so fusion of gametes and subsequent embryo development remained undiscovered.