Endocrinology Biology 559 Endocrinology Biology 559

Dr. Frank V. PaladinoDr. Frank V. PaladinoJack W. Schrey Distinguished ProfessorJack W. Schrey Distinguished ProfessorDepartment of BiologyDepartment of BiologyIndiana – Purdue University, Fort WayneIndiana – Purdue University, Fort Wayne

3 Exams 100 pts plus 1 research paper due Dec 5, 2004

Terms and Definitions• Endocrine System – A chemical communication

system designed to control cell, tissue, organ & organism function

• Hormone – a chemical compound produced by cells in trace quantities, secreted directly into the blood & then carried via circulation to other cells, the function of which are changed by this chemical

• Target cell, tissue or organ – those cells or organs that are affected by a hormone

• Endocrine gland – the cells that produce a hormone

Typical endocrine cellSecretion of hormone directly into blood

Mechanisms of Hormone Action

• Two Basic or General Classes of Hormones

• 1. Hormones that work on target cell membrane

• a. amino acid or protein type

• b. membrane receptors

• c. Adenyl cyclase enzyme in membrane

• d. cAMP or cGMP formed and act as 2nd messenger and changes cell function in cytoplasm

Amino acids and proteins are charged particles and can not easily permeate the cell membrane. They attach to membrane receptors

• Hormones that act on the cell nucleus

• 1. These tend to be lipids or fats

• 2. Because they are lipids they can easily permeate through the cell membrane and easily get into cell

• 3. These lipids then attach to intracellular receptors in the cytoplasm

• 4 They then migrate to the nucleus as a receptor-hormone complex and then attach to the DNA a specific sites

• 5. DNA transcription of new mRNA’s is then initiated and cell function is thus changed