EXPORT CITATION

Chapter 1.4 Physicochemical Principles of Biological Transport

BOOK TITLE: Understanding Medical Physiology: A Textbook for Medical Students

Author
1. Bijlani R.L.
ISBN
9788180612213
DOI
10.5005/jp/books/10999_4
Edition
3/e
Publishing Year
2004
Pages
7
Author Affiliations
1. All India Institute of Medical Sciences, New Delhi
Chapter keywords
physicochemical principles, carrier protein, facilitated diffusion, collisions, pressure gradient, carrier molecules, blocking agent, transported substance, hydrostatic pressure, electrochemical gradient, symport, cotransport, dialysis, ultrafiltration, gastrointestinal tract, metabolic energy, uphill transport, antiport

Abstract

This chapter discusses physicochemical principles of biological transport, where passive transport across the cell membrane depends on physical factors such as concentration gradient, electrical gradient and pressure gradient. Lipid soluble substances are transported faster because such substances can dissolve in the lipid bilayer of the cell membrane and cross it. The major processes by which passive transport is accomplished are simple diffusion, facilitated diffusion and osmosis. The frequency of collisions depends on the concentration of the dissolved substance. Respiratory gases are transported across the alveolar membrane in the lungs by simple diffusion. Osmosis is a special instance of diffusion. Substances with a similar molecular structure compete with one another for transport. Active transport utilizes biologically produced energy. Minor differences in molecular structure may lead to a substantial difference in the rate of transport. Hydrostatic pressure is a pushing pressure. Osmotic pressure is a pulling pressure.

© 2019 Jaypee Brothers Medical Publishers (P) LTD.   |   All Rights Reserved