PSL201Y1 Chapter : PSL201 – Feb 14 – Endocrine 1 Introduction to Hormones.docx
Document Summary
All body functions require communication between cells there are only a few mechanisms in the body for cells to communicate with one another few instances: linked by gap junctions. Gap junctions link adjacent cells formed by connexins (plasma membrane proteins) form channels that allow molecules to pass through. Metabolically couples cells so that one cell can provide for another. Indirect communication through chemical messengers chemical messenger = ligand (molecules that bind to proteins reversibly) Hundreds of chemical messengers with different functions. One cell releases a chemical into the interstitial fluid (secretion) Another cell (target cell) responds to the chemical messenger b/c of its receptors, which specifically recognize the ligand: this binding produces a response in the target cell through signal transduction. Strength of response increases as the number of bound receptors increases: bound receptors increases as [messenger] in isf increases. Chemical messengers classified on basis of structure and function. 3 main categories: paracrines, neurotransmitters, hormones.
