سلول

http://translate.google.com/translate?hl=en&sl=fa&u=http://www.iran-stu.com/f

Cell physiology (2)

Published in:

Molecules of a gas dissolved in a solution of molecules and ions are in the situation of constant random motion due to their thermal energy is. This random movement is called diffusion and spread evenly disperse the molecules that are dissolved in a certain volume. Called The net release. Release is purely physical process of establishing the difference starts. When there is a difference in the two sides of the membrane, the release of membrane transport is considered.

Diffusion through the cell membrane:
Since the cell membrane is essentially a double layer of lipid phosphatides, nonpolar and lipid-soluble molecules can pass easily from one side of the membrane to the other side. In other words, the cell membrane barrier to the release of non-polar molecules, such as oxygen and steroid hormone, does not. As well as small molecules such as CO2 or ethanol without charge and contains covalently bonds and urea can penetrate the phospholipid double layer. Therefore net release of these molecules can easily be performed between inside and outside of the cell, until the establishment of gradient to occur.
Although water soluble, not fat, but due to lack of net charge and small size of molecules that can be released through the cell membrane. However, some of the water through the membrane chaels is limited to the net that can be opened and closed in response to physiological regulation.
Note: Net diffusion of water molecules across the membrane is known as osmosis. Osmosis is the diffusion of simple solvent rather than the solution, to justify its use of the term is pure.

Velocity:
Velocity of molecules passing through the membrane width, measured in units of time, and depends on the following factors:
1 - a big difference in the width of the membrane (concentration gradient) 2 - permeability of the membrane to the material being published in 3 - May membrane surface area of the place set up across the membrane materials are published.

RO:
Published osmosis purified water (solvent) across a membrane.
Ratjsm cylinder that can freely move through the artificial membrane is divided into two equal parts. Begiing of the segment containing g / l 180 was glucose, while other parts g / l 360 glucose . If the pressure in a glucose permeable, in this case, as long as any part of the concentration of 270 grams per liter to reach the glucose unit of g / l 360 to g / l 180 spread. Injured membrane to glucose impenetrable, but the water permeable, the effect on the release of water as a result of (a solution with concentration g / l 270 each either side of the membrane) can be achieved will be. still water part of concentration, g / l 180 to g / l 360 published will last more concentrated solution, the next solution is further diluted., it is associated with volume changes., when the concentration is equal on both sides of the membrane, osmosis stops. This could be due to the water levels of the lipid membrane barrier often behave in the same way would be the cell membrane. However, some are water-specific membrane chael Sully, who may be under the regulation. This is particularly important in kidney function. Thus, the occurrence of osmosis, the membrane must be semi-permeable, which means that the water molecule is more permeable molecules dissolved in water.

Note: Due to the phenomenon of osmosis water and solute molecules can be serious, classified discussion is acceptable and appropriate for Mvlalyth concentration. Molale a solution, one mole of solute (eg glucose, 180 g) is dissolved in a kilogram. A solution of salt and a Molale a glucose solution containing one mole of solute in a Molale both are the exact same amount of water, have been resolved. If you make a molar solution of NaCl with a molar glucose more water is needed than 85.5 g NaCl and 180 g glucose greater volume accounts.