6.6
D.5
hormones, homeostasis, & reproduction
Essential Idea: Hormones are not secreted at a uniform rate and exert their effect at low concentration. Hormones are used when signals need to be widely distributed.
​
Nature of Science: Cooperation and collaboration between groups of scientists: the International Council for the Control of Iodine Deficiency Disorders includes a number of scientists who work to eliminate the harm done by iodine deficiency. 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.
UNDERSTANDINGS:
-
D.5.U1 Endocrine glands secrete hormones directly into the bloodstream.
-
D.5.U2 Steroid hormones bind to receptor proteins in the cytoplasm of the target cells to form a receptor-hormone complex
-
D.5.U3 The receptor-hormone complex promotes the transcription of specific genes.
-
D.5.U4 Peptide hormones bind to receptors in the plasma membrane of the target cells.
-
D.5.U5 Binding of hormones to membrane receptors activates a cascade mediated by a second messenger inside the cell.
-
D.5.U6 The hypothalamus controls hormone secretion by the anterior and posterior lobes of the pituitary gland.
-
D.5.U7 Hormones secreted by the pituitary control growth, development changes, reproduction, and homeostasis.
-
6.6.U1 Insulin and glucagon are secreted by ‘B’ and ‘a’ cells in the pancreas.
-
6.6.U2 Thyroxin is secreted by the thyroid gland to regulate metabolic rate and help control blood 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 prenatal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.
-
6.6.U7 Oestrogen and progesterone cause prenatal 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.
APPLICATIONS & SKILLS:
-
Application: Some athletes take growth hormones to build muscles
-
Application: Control of milk secretion by oxytocin and prolactin.
-
Application: Causes and treatment of Type I and Type II diabetes.
-
Application: Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
-
Application: Causes of jet lag and use of melatonin to alleviate it.
-
Application: 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.
-
Application: William Harvey’s investigation of sexual reproduction in deer.
-
Skill: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.
​
RESOURCES:
​​
