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Endocrinology Biology 559
Dr. Frank V. Paladino
Jack W. Schrey Distinguished Professor
Department of Biology
Indiana – 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 cell
Secretion 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 receptorhormone 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