5. The transport functions of the plasma membrane
5. The transport functions of the plasma membrane
- Gillian Pocock, Gillian PocockSenior Lecturer in Clinical Science, Canterbury Christ Church University, Canterbury, UK
- Christopher D. RichardsChristopher D. RichardsEmeritus Professor of Experimental Physiology, Division of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University College London, London, UK
- and David A. RichardsDavid A. RichardsAssociate Professor, Department of Basic Pharmaceutical Sciences, Husson University School of Pharmacy, Bangor, Maine, USA
Abstract
This chapter looks at the plasma membrane, wherein the region outside the cell or the extracellular compartment is separated from the inside of the cell or intracellular compartment. It shows how the physical separation allows each cell to regulate its internal composition independently of other cells. Chemical analysis has shown that the composition of the intracellular fluid is very different to that of the extracellular fluid, noting that it is rich in potassium ions but relatively poor in both sodium ions and chloride ions. The chapter highlights the mechanisms responsible for establishing and maintaining the difference in ionic composition between the intracellular and the extracellular compartments. The chapter outlines the ways in which cells utilize ionic gradients to perform their essential physiological roles and the mechanisms by which proteins and other large molecules cross the cell membrane.
