Hormones and Homeostasis
Hormones are used when signals need to be widely distributed to maintain homeostasis.
IB Assessment Statements and Class Objectives
Endocrine glands secrete hormones directly into the bloodstream.
Hormones secreted by the pituitary control growth, developmental changes, reproduction and homeostasis.
The hypothalamus controls hormone secretion by the anterior and posterior lobes of the pituitary gland.
Steroid hormones bind to receptor proteins in the cytoplasm of the target cell to form a receptor–hormone complex.
The receptor–hormone complex promotes the transcription of specific genes.
Peptide hormones bind to receptors in the plasma membrane of the target cell.
Binding of hormones to membrane receptors activates a cascade mediated by a second messenger inside the cell.
Insulin and glucagon are secreted by beta and alpha cells of the pancreas respectively to control blood glucose concentrations.
Causes and treatment of Type I and Type II diabetes .
Overweight individuals are more likely to suffer hypertension and type II diabetes.
Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
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.
Appetite is controlled by a centre in the hypothalamus.
Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
Melatonin is secreted by the pineal gland to control circadian rhythms.
Causes of jet lag and use of melatonin to alleviate it.
Some athletes take growth hormones to build muscles.