Endocrine glands secrete hormones directly into the bloodstream.
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.
The hypothalamus controls hormone secretion by the anterior and posterior lobes of the pituitary gland.
Hormones secreted by the pituitary control growth, developmental changes, reproduction and homeostasis.
Some athletes take growth hormones to build muscles.
Control of milk secretion by oxytocin and prolactin.
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.