BIOD27H3 Chapter Notes - Chapter 5: Dynamic Equilibrium, Extracellular Fluid, Passive Transport
Document Summary
to maintain homeostasis, the body uses mass balance. membrane permeability is variable and can be changed by altering the proteins or lipids of the membrane. the size of the molecule and its lipid solubility influence its movement across membranes (large, less lipid-soluble molecules usually cannot pass the membrane unless the cell has specific membrane proteins to transport them or vesicles to move them) passive transport: movement across the membrane not requiring energy input. active transport: movement across the membrane needing energy input. Ion movement depends on electrical gradient because of the attraction/repulsion of charges. membrane proteins function as structural proteins, enzymes, channel proteins allow more rapid transport across the membrane, but limited to transporting small ions and water. carrier proteins are slower, but can move larger molecules. gated channels may be chemically gated (messenger molecules), voltage-gated (electric state), or mechanically gated (physical forces)
