Table of Contents
Passive Transport Definition
An instance of passive transport in action. A channel protein transports water-soluble compounds along the concentration gradient across the membrane (an example of facilitated diffusion). Fat-soluble compounds pass through the lipid bilayer membrane with ease (an example of unassisted diffusion).
Passive transport is a method of transporting substances from a high-concentration to a low-concentration region. As a result, chemicals travel in a concentration gradient.
What is Passive Transport?
Passive transport refers to the movement of things such as ions and molecules along concentration gradients. It indicates that the drug prefers to migrate from a high-concentration location to a low-concentration area. Substances gravitate to areas where there are fewer of them.
Active transport, another kind of cellular transport that fundamentally requires ATP to move substances against their concentration gradient, does not require metabolic energy (e.g. ATP) since its movement is downhill or along its concentration gradient. Simple diffusion, assisted diffusion, filtration, and osmosis are the four primary forms of passive transport.
Passive Transport vs Active Transport
Passive and active transport are two types of cellular transport processes that a cell uses to transfer things across a biological membrane. Passive transport, on the other hand, differs from active transport in that the chemicals travel in the direction of their respective concentration gradients, whereas active transport moves substances against their gradients. In passive transport, substances travel in the opposite direction as they do in active transport.
In passive transport, the concentration is transferred from one location to another with a lower concentration. The direction of travel is described as downward. As a result, unlike active transport, cellular energy (e.g. ATP) is not required. Passive transportation, on the other hand, is propelled by kinetic and natural energy. Active transportation, on the other hand, moves people uphill, from a less densely populated region to one where it is already densely populated. As a result, ATP is commonly used as the driving force in the process.
Types of Passive Transport
Passive transport may or may not require the aid of a membrane protein when transporting molecules across a biological membrane.
(1) simple diffusion,
(2) assisted diffusion,
(3) filtration, and
(4) osmosis are the four primary forms of passive transport.
The net migration of molecules from higher to lower concentrations is referred to as simple and assisted diffusion. The migration of a solvent (typically water molecules) from lower to higher solute concentrations via a semipermeable membrane is referred to as osmosis. Filtration is the process of moving water and solute molecules across a cell membrane, which is aided by the circulatory system’s hydrostatic pressure.
Passive Transport Examples
Plants and animals require passive transport in order to operate properly. Gases such as carbon dioxide and oxygen, for example, diffuse into and out of plant cells through stomatal openings based on concentration gradients. Plants require carbon dioxide because it is one of the primary reactants in photosynthesis. Animals that emit carbon dioxide during expiration are one of the sources of the gas. Passive transport is responsible for the emission of carbon dioxide into the atmosphere.
Carbon dioxide diffusion occurs between the blood and the tissue fluid, in particular at the capillary beds. It travels from the tissues to the blood, then to the lungs, where it diffuses from the blood into the alveoli before being exhaled. As carbon dioxide leaves the body, oxygen enters the lungs and is delivered into the body’s tissues by simple diffusion.
Passive Transport Citations
- Passive water transport in biological pores. Int Rev Cytol . 2002;215:203-30.
- Cell Membrane Transport Mechanisms: Ion Channels and Electrical Properties of Cell Membrane. Adv Anat Embryol Cell Biol . 2017;227:39-58.
- Vitamin E intestinal absorption: Regulation of membrane transport across the enterocyt. IUBMB Life . 2019 Apr;71(4):416-423.