Genuflexion to Devotees of the CS art, Body cells have much in common with each other, yet those of different tissues vary in a number of ways. Most of the trillions of cells within the human body are to small to be seen without a microscope. Only the human egg cell can be seen with the unaided eye, as a tiny speck. Cells vary in size, shape, and complexity, determined by their function and purpose. Secretory cells are no exception, being specially constructed to do what they do with great efficiency. Osmoregulatory cells, such as secretory, excretory and homeostatsis epithelia act as highly specialized ionic pumps, and have special structural features. The secretory cells of the sweat glands possess extensive systems of smooth endoplasmic reticulum, dense populations of mitochondria containing large numbers of cristae, and, frequently, extensive deep infoldings of the cell membrane on the side of the cell where absorption is presumed to occur. Lets take a quick look at some of the cell contents. We know that cells are enclosed in a thin membrane and that within this membrane there are hundreds more membranes enclosing separate sections and organs of the cell. Of great interest to us are the cytoplasm, endoplasmic reticulum, ribosomes, Golgi apparatus, and the mitochondria. There are many other organs (organelles) in a cell, but these are the ones of interest to us at this moment. The cytoplasm is the clear thick liquid (as seen by the eye) that fills the cell. The electron microscope shows it to be filled with all kinds of cell machinery, networks of tubules, membranes, and other organelles, no space is wasted. The activities of the cell occur largely in its cytoplasm. It is there that food molecules are received, processed and used, it is the site of the cells metabolic processes, in which the other mentioned cytoplasmic organelles play specific roles. The endoplasmic reticulum is a complex network of interconnected membranes. Spaces between these membranes form elongated canals called tubules. The network is connected to the cells outer membrane , where it has openings to the outside of the cell. It also connects to the other organelle and functions as a transporting network, moving chemicals from one part to the other parts of the cell. The endoplasmic reticulum also functions in the synthesis of the chemicals it is distributing in the cell. A part of the membrane surface is smooth and part is rough, having ribosomes on it. The smooth surface is very active in producing secretory fluids. The ribosomes produce proteins, enzymes, other secretory products, which are used for cell building and secreted outside of the cell. The Golgi apparatus (named after Doctor Golgi) is composed of a group of flattened, membranous sacs whose membranes are continuous with those of the endoplasmic reticulum. The Golgi apparatus manufactures cellular secretions as packages of glycoproteins which are released outside of the cell as secretion. Mitochondria are fairly large, fluid-filled sacs. They vary in size and can change shape; often they can be observed moving about in the cytoplasm. The membrane surrounding a mitochondrion has an outer and an inner layer. The inner layer is folded to form partitions called cristae within the sac-like structure. Small particles thought to be associated with enzymes are connected to the cristae. These enzymes control the chemical reactions by which energy is released from the glucose molecules. The mitochondria function in the transformation of this energy into a form that is usable by cell parts. The mitochondria are the power houses of the cell, changing incoming chemicals into chemicals that the cell can use for energy. Secretory cells require large amounts of energy to function, as all of their activities are against the normal gradients found in normal cells. All cells have mitochondria, which supply ATP, to power the cell activities. Cells that require larger amounts of energy have larger numbers of mitochondria, a heart muscle cell will have as many as 50,000 in the cell, due to the high energy requirement of the heart cell. Secretory cells, such as the sweat cell have them in the many thousands. The more energy required, the more mitochondria are found in the cell. The mitochondria is a separate living organism in its own right. It has its own membrane, its own DNA, and all thats required to exist as a separate bacteria. It multiplies and divides when more are needed, and when the cell divides each half will get its starter group of mitochondria to populate it. Biologists now believe that long ago the mitochondria were bacteria that formed a symbiotic relationship with the living cell, a relationship that was to transform the cell so much that all cells from yeasts through human beings could not survive without them. The primitive algae did not have available extra energy, never had a way of creating more energy, and never developed past the algae development. When mitochondria formed a symbiotic relationship the primitive cell now had a way of producing extra energy from foods, and in consequence became capable of building larger more complex structures, creating electricity, doing forceful secretions, moving about in its environment and actively pursuing food. Evolution would have stopped without the mitochondria. The usual picture is that an early cell tried to digest a mitochondria bacteria and it resisted successfully and remained in the cell. Who knows, we do know it is there in all our cells now. The ATP, which is the waste of the mitochondria is the energy for the cell. A molecule of glucose enters the cell and is acted upon by enzymes, after nine successive chemical reactions, the glucose molecule becomes two molecules of pyruvate, which then enters the mitochondria. In the mitochondria the pyruvate is processed to release energy in the form of electrons (the stuff of electricity) which are immediately recaptured to make ATP (adenosine triphosphate) which in turn is transported to all parts of the cell, providing the chemical power needed by the cells components. As the energy is used from the ATP it becomes ADP and returns back to the mitochondria for more energy, changing back into ATP again. This happens million of times per second, per mitochondria, per sweat cell, per sweat gland. Thats a lot of energy being created and used by the sweat glands. A result of all this energy creation and use is water, a lot of it, which is secreted by the cells through their membranes. Also the sodium-potassium pumps go into high gear, producing a secretion of salt on the skin in the water. This whole process builds up in just seconds as the hormones and electrical stimuli call for sweat. The mitochondria begin multiplying rapidly and glucose intake rises sharply, ATP production goes into high gear and water and salt begin coming from the cell within seconds of the demand for sweat. So what is the sodium-potassium pump doing? For every glucose molecule that enters the cell a sodium atom must accompany it, soon the cell will have to many sodium atoms. The sodium-potassium pump will force sodium atoms out of the cell, and in so doing this two potassium atoms come in for every three sodium atoms forced out. This is good because the cell is constantly losing potassium atoms in other chemical actions and they need to be replaced to maintain the proper ionic balance. This forcing out of sodium and forcing in potassium use energy which requires more glucose intake and round and round it goes. The excess sodium appears in the sweat, mixed with the water in the ducts on its way to the skin surface.
--to be continued--- Bless you, Bob Lee -- oozing on the muggy shore of the gulf coast [email protected] -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
