Physiology & Pathophysiology Module 1- Membrane Physiology & Action Potentials (Long) Questions And Answers (A+ Grade)

Physiology & Pathophysiology Module 1- Membrane Physiology & Action Potentials (Long) Questions And Answers (A+ Grade) 1. Explain the structure of the membrane - ANS-Cell Membranes are composed primarily of lipids and proteins. Lipids consist of phospholipids, cholesterol, glycolipids - high permeability of membranes to lipid soluble substances (CO2, fatty acids, steroid hormones). Lips are also responsible to the low permeability of water-soluble molecules (ions, glucose, amino acids). Proteins: Transporters, enzymes, cell surface antigens, ion / water channels, and hormone receptors. Proteins function as transport channels, enzymes, cell surface receptors, cell surface markers (glycoprotein), cell adhesion molecules, attachment of cytoskeleton. Directional transport is facilitated by polarized domains, distinct apical and basolateral domains Explain Phospholipids: - ANS-A phospholipid Molecule, consists of a phosphate functional group and a two fatty acid chains attached to a glycerol molecule. Consist of phosphorylated glycerol backbone (head and hydrophilic=water soluble) and 2 fatty acid tails (hydrophobic=water insoluble). This makes them amphiphathic (water soluble / water insoluble). (1) The fatty acid chains and glycerol form NON-POLAR hydrophobic "tails". (2)The phosphate functional group forms the POLAR, hydrophillic HEAD. When placed inward the hydrophobic tails of the molecule face inward = away from water / and the hydrophobic head faces outward toward the water. = Acts as a barrier to the diffusion of water and hydrophilic substances, while allowing lipid-soluble molecules such as oxygen and carbon dioxide to diffuse through it readily. What is glycocalyx - ANS-Negatively charged carbohydrate layer on the outside of the membrane - receptor for insulin and attracts to other cells Diffusion - ANS-movement of a solute molecule from an area of greater solute concentration to an area of lesser solute concentration. High to Low concentraton. The smaller the molecule, more soluble it is in oil, the more hydrophobic or non-polar it is, and the more rapidly it will diffuse across the bilayer. fatty acids / Oxygen / CO2 / nitrogen / water / urea / glycerol/ Steroid hormones = All non-polar and diffuse fast. Whereas water-soluble substances = sugars inorganic ions = diffuse slow Rate of diffusion Simple - no help --> increases with greater +/- changes ICF and ECF - Net diffusion is proportional to the difference in concentration across the membrane. Rate of Facilitated Diffusion: Limited by speed of carrier protein - VMAX - max rate - so adding more carriers should not affect VMAX Mediated Transport - ANS...