Introduction
Transportation is defined as the process of moving or distributing various materials or goods from one location to another. The majority of the time, we humans travel using a variety of modes of transportation. A similar network of transportation systems exists in the living system, including plants, animals, and humans, which is involved in the circulation of food, minerals, hormones (including oestrogen and progesterone), oxygen, carbon dioxide, and waste products, among other things.
Transportation
There are two types of transportation in our body: Active and Passive Transport, both of which aid in the transportation of biochemical nutrients such as water and oxygen to the cells.
Active transport is the biological process of molecules moving against a concentration gradient. It is also referred to as diffusion transport. As a result, chemical energy is required to transport the components from lower to higher concentrations in different areas or parts of the body.
Passive transport is the biological process by which biochemicals are transported across cell membranes and between tissues.
Simple Diffusion
A simple diffusion process always occurs down an electrochemical gradient, which is a composite of the concentration and electrical gradients in the environment (electrochemical gradient). When dealing with an undissociated molecule, only the concentration gradient is important; when dealing with a charged ion, the electrical gradient must also be taken into consideration. Simple diffusion does not necessitate the use of a direct energy source, though active transport is usually required to establish the initial concentration and electrical gradients in the solution.
Facilitated Diffusion
Facilitated diffusion (also known as coupled or carrier-mediated diffusion) is a type of diffusion that occurs when a molecule or ion interacts with a specific membrane carrier protein, which allows the molecule or ion to pass more easily through the lipid bilayer of the cell membrane. It is almost always the case that two or more ions or molecules share a carrier in the kidney: one moiety moves down its electrochemical gradient, while the other(s) moves against the gradient and is transported “uphill” as the name implies.
Diffusion through a membrane channel (or pore) formed by specific integral membrane proteins is also referred to as facilitated diffusion, because it allows charged, polar, and lipophilic molecules to pass through the membrane at a high rate, whereas diffusion through an open membrane channel (or pore) does not.
Molecular passive transfer across a membrane is dependent on several factors, including
(1) concentration and electrochemical differences across the membrane,
(2) molecular weight,
(3) lipid solubility,
(4) degree of ionisation, and
(5) the surface area and thickness of the membrane. When a concentration gradient is present, the passive transfer takes place through the lipid membrane (for example, between lipophilic molecules and water) or within protein channels that traverse the lipid bilayer.
Passive transport, in which movement occurs without the use of energy, is characterised by the simple diffusion of fat-dissolvable and non-polar molecules. Diffusion of oxygen, carbon dioxide, and fats occurs from the side with the higher concentration to the side with the lower concentration, until a balance is achieved between the two sides. All water is excluded from the placenta, except for the water that enters through specialised pores by osmosis known as aquaporins or water channels.
Simplified transport is characterised by the transition from a lower to a higher solute concentration with the assistance of transport molecules (for example, glucose) or the use of energy. Active transport is the movement of macromolecules through the cellular membrane against a concentration gradient using energy (Na+/K+ or Ca++), whereas vesicular transport is the movement of macromolecules through the cellular membrane that are captured by microvilli and absorbed or repelled in the cells by Endocytosis or Exocytosis. From 5 m2 at 28 weeks of pregnancy to approximately 12 m2 shortly before delivery, the placental exchange surface increases dramatically.
Examples Of Passive Transport
The following are some examples of passive modes of transportation:
- Ethanol is absorbed into our bodies and circulates in our blood. This occurs as a result of the ethanol molecules undergoing simple diffusion and passing through the cell membrane without the need for external energy.
- The process by which nutrients are reabsorbed by the intestines by separating them from solid waste and transporting the nutrients through the intestinal membrane to the bloodstream.
- The water that is soaked into the raisin moves into the raisin through the process of osmosis and causes the raisin to expand.
Conclusion
Passive transport is defined as the movement of a solute from a region of high electrochemical potential on one side of the cell membrane to a region of lower electrochemical potential on the other side of the cell membrane.