Essential idea: Hormones are used when signals need to be widely distributed.
Thyroxin (above) is a hormone produced by the thyroid gland. It's key role is in controlling the metabolism of cells. If affects almost every physiological process in the body including growth and development. Most hormones affect more than one target tissue in more than one way.
Understandings, applications and skills
|6.6.U1||Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.|
|6.6.U2||Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.|
|6.6.U3||Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.|
|6.6.U4||Melatonin is secreted by the pineal gland to control circadian rhythms.|
|6.6.U5||A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.|
|6.6.U6||Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.|
|6.6.U7||Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.|
|6.6.U8||The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. [The roles of FSH, LH, estrogen and progesterone in the menstrual cycle are expected.]|
|6.6.A1||Causes and 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.|
|6.6.A3||Causes of jet lag and use of melatonin to alleviate it.|
|6.6.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.|
|6.6.A5||William Harvey’s investigation of sexual reproduction in deer. [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.]|
|6.6.S1||Annotate diagrams of the male and female reproductive system to show names of structures and their functions.|
[Text in square brackets indicates guidance notes]
Presentation and Notes
The presentation is designed to help your understanding.
The 6.6 Hormones, homeostasis and reproduction notes - the bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.
Quick quiz Use the BioK Quick Quiz on 6.6 Hormones, homeostasis and reproduction (as directed) to check your understanding of the topic.
Nature of science
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)