Topic 6.6: Hormones, Homeostasis and Reproduction

Essential Idea:  Hormones are used when signals need to be widely distributed.
At SHS, Topic 6.6 is taught in the following class unit(s):

Statements & Objectives:

6.6.U1  Insulin and glucagon are secreted by beta and alpha cells of the pancreas respectively to control blood glucose concentrations.
  • Explain the control of blood glucose concentration, including the roles of glucagon, insulin and the alpha and beta cells in the pancreatic islets.
6.6.U2  Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
  • Describe the structure and function of thyroxin.
  • Outline thyroxin’s role in body temperature regulation.
  • List symptoms of thyroxin deficiency.
6.6.U3  Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
  • State that leptin is a protein hormone.
  • Outline the mechanism of action of leptin.
  • Describe the role and discovery of the ob allele in obese mice.
6.6.U4  Melatonin is secreted by the pineal gland to control circadian rhythms.
  • Define circadian rhythm.
  • Describe the secretion and action of melatonin.
  • Outline the mechanism that regulates melatonin secretion in response to the day-night cycle.
6.6.U5  A gene on the Y chromosomes causes embryonic gonads to develop as testes and secretes testosterone.
  • Describe the mechanism by which the SRY gene  regulates embryonic gonad development.​​ ​
6.6.U6  Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.
  • Outline role of testosterone in prenatal development of male genitalia.
  • State testosterone's role in stimulating the primary sexual characteristic of males.
  • List secondary sexual characteristics triggered by testosterone at puberty.
6.6.U7  Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.
  • State the sources of estrogen and progesterone used in embryonic development.
  • Describe prenatal development of female reproductive organs.
  • List secondary sexual characteristics triggered by estrogen and progesterone at puberty.
6.6.U8  The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.
  • Outline events occurring during the follicular and luteal phases of the menstrual cycle.
  • State the source and location of action of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinising hormone), estrogen and progesterone.
  • Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinising hormone), estrogen and progesterone.
  • Describe the negative feedback loops that regulates secretion of FSH.
  • Describe the positive feedback loop that regulates secretion of estrogen.
  • Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and follicular development, ovulation, changes to the corpus luteum, menstruation and the thickening of the endometrium.
6.6.A1  Causes and treatment of Type I and Type II diabetes.
  • Distinguish between causes of type I and type II diabetes.
  • Distinguish between treatment of type I and type II diabetes.​
6.6.A2  Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
  • Explain the double blind study that tested the effect of leptin treatment on human obesity.
  • Outline role of leptin resistance in human obesity.
6.6.A3  Causes of jet lag and use of melatonin to alleviate it.
  • State symptoms of jet lag.
  • Outline the biological cause of jet lag.
  • Describe use of melatonin in treatment for jet lag.​
6.6.A4  The use of 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.
  • Define in vitro fertilization.
  • Outline the process of in vitro fertilisation including down-regulation, superovulation, harvesting, fertilization and implantation.
6.6.A5  William Harvey’s investigation of sexual reproduction in deer.
  • Outline Harvey's methods of studying reproduction.
  • State Harvey's discovery about reproduction. 
6.6.S1  Annotate diagrams of the male and female reproductive system to show names of structures and their functions.
  • Label a diagram of the male reproductive system, including the bladder, sperm duct, penis (with foreskin and erectile tissue), urethra, testis, scrotum, epididymis, prostate gland and seminal vesicle.
  • Outline the function of the following male reproductive structures:  testis, scrotum, epididymis, sperm duct, seminal vesicle, prostate gland, urethra and penis.
  • Label a diagram of the female reproductive system, including the ovary, uterus, bladder, urethra, vulva, vagina, cervix and oviduct.
  • Outline the function of the following female reproductive structures: ovary, oviduct, uterus, cervix, vagina, and vulva.​
6.6.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.
  • Describe what Harvey was and was not able to observe in his reproduction research given the tools available at the time.​

In the News:
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911