HN220 Lecture Notes - Lecture 2: Membrane Potential, Sodium-Potassium Alloy, Cardiac Muscle
Document Summary
How do they communicate: 2 basic ways, electrical signals, changes in membrane potential, chemical signals, secreted by cells into ecf, responsible for most communication in body, cells responding are called target cells. Fundamental stages to signal transduction: reception, transduction, response. Long-distance: combination of electrical & chemical signals, electrical by nerve cells, chemical by blood (hormones) Found in epithelium limits molecule movement: occludins (integral proteins that fuse adjacent cells, form a nearly impermeable barrier, forces molecule to cross the epithelial cell layer. Apical membrane (lumen) epithelial cell cytosol basolateral membrane (ecf) Ions and molecules moving between cells act as a signal: communication is direct, connexins, gap junction protein, spans membrane creating a channel, when channel is open cells act as 1, 20 different types of connexions. Intracellular communication coordinate cell activity for homeostasis: direct. Chemical messengers released by one cell act on specific receptors on another cell.
