Renin-Angiotensin (RA) system activity (see Figure 12) is a subordinate mechanism to histamine activation in the brain. The RA system is also recognized to be very strongly active in the kidneys. This system is activated when the fluid volume of the body is diminished. It is activated to retain water, and to do so, it also promotes the absorption of more salt. In either water or sodium depletion of the body, the RA system becomes very active.
Until water and sodium content of the body reach a preset level, the RA system also brings about the tightening of the capillary bed and the vascular system. It is designed to do this so there is no 'slack' and empty space in the circulation system. This tightening can reach such a level that it becomes measurable, and we call it hypertension. You think a reading of 200 points is high? I have seen the blood pressure of a man without prior history of hypertension reach a level of 300 millimeters of mercury, 300 points, when he was arrested and taken to one of the Iranian political prisons to be shot.
The reason for this tightening of the blood vessels during stress is simple to understand. The body is a highly integrated and efficient complex multi-system. When there is stress, some of the available water is used for the breakdown of stored materials, such as proteins, starch (glycogen)and fat. To compensate for the lost water and to put the system into a squeeze, the RA system will also coordinate work with vasopressin and other hormones. The kidneys are the main site of/RA system activity.
The kidneys are responsible for urine production and the excretion of excess hydrogen, potassium, sodium, and waste materials. All of these functions have to be maintained proportionate to the sufficient availability of water to be used to make urine. It is true the kidneys have the ability to concentrate the urine. However, this ability is not to be used to its extreme at all times, or it will eventually produce kidney damage.
The RA system is the pivotal mechanism for the restoration of fluid volume in the body. It is one of the subordinate mechanisms to histamine activity for water intake. It regulates the vascular bed to adjust for the fluid content of the circulation system. Its activity is decreased by the presence of more salt and water to fill the fluid capacity of the vascular bed. In the kidneys, it senses the fluid flow and the filtration pressure for its urine-making system. If the filtration pressure is not adequate for urine filtration and secretion, the RA system will tighten the blood vessels in this organ.
When the kidneys are damaged and urine production is insufficient, the RA system is more active. It promotes more salt intake and induces more thirst. Kidney damage may be the consequence of long-term dehydration and salt depletion that had triggered the RA system activity in the first place. But we have not in the past recognized the significance of the vascular tightening (essential hypertension) as an indicator of body's fluid loss. Now, insufficient fluid balance in the body may have to be considered as the primary factor in some cases of renal damage—to the point of needing kidney replacement. Once the RA system is turned fully ON, it continues its expanding pace until a natural switching system could turn it off. The components of the natural OFF switch are WATER and some SALT—in that order—until the measurable vascular tightening indicates a normal range.
The salivary glands seem to have the ability to sense salt shortage in the body. When there is sodium shortage, they seem to produce substances called kinins. Kinins promote added blood circulation and increased saliva formation in the salivary glands. This increased saliva formation (possibly to the extent that it would flow out of the mouth) serves two purposes: One, it lubricates the mouth during food intake in a dehydrated state of the body; two, its alkaline consistency and copious flow will assist in food breakdown and its eventual evacuation from the stomach. Within the integrated systems of the human body, the kinins of the salivary gland seem to also trigger activation of the RA system that will begin to influence all parts of the body.
Thus, sodium (salt) shortage in the body (which would also contribute to devastating water shortage outside of cells) could initiate a series of events that would ultimately produce essential hypertension and chronic pains in humans. The relationship of the salivary kinins to sodium depletion (salt depletion causes body water content loss) and ample saliva production, even if the body is fairly dehydrated, is the paradox in the natural design of the human body. It exposes the grossest error in considering the 'dry mouth' as the sole indicator of water shortage in humans! Because of this very simple error, the practice of medicine and scientific research are light years off course. Much backtracking and revision to the already adopted views will be unavoidable. Let us hope 'self protection' will not be an obstacle in the way!
What happens if we drink tea, coffee, or colas in place of water? Natural stimulants in coffee and tea are larger quantities of caffeine and lesser amounts of theophylline (theafelin). These are central nervous system stimulants; at the same time, they are dehydrating agents because of their strong diuretic action on the kidneys. One cup of coffee contains about 85 milligrams of caffeine, and one cup of tea contains about 50 milligrams of caffeine. Cola drinks contain about 50 milligrams of caffeine, part of which is added to standardize the recipe when extracting the active substances from the nuts of Cok accuminata.
These central nervous system stimulants liberate energy from the ATP storage pool and convert ATP to its burnt stage of cyclic AMP in the cells—at certain levels a strong inhibitory agent. They also release energy from liberation of calcium from its stored form in the cells. Thus, caffeine seems to act in an energy releasing capacity in the body. We all know about this final effect of caffeine; what we should also know is its override effect when the body does not wish to release energy for a certain action. In this way, the action of some hormones and transmitters will not be limited at a later time because of a possible lower level of stored energy. Caffeine will cause an override effect until a lower level of energy storage is reached. Cola drinks have exactly the same effect.
The effect of caffeine may at times be considered desirable, but constant substituting of caffeine-containing drinks for water will deprive the body of its full capacity for the formation of hydroelectric energy. Excess caffeine will also deplete the ATP-stored energy in the brain and the body—a possible contributing factor for shorter attention span in the younger, cola-consuming generation, or chronic fatigue syndrome as a result of excess coffee consumption In later life. Excess caffeine intake will eventually exhaust the heart muscle because of its over-stimulation.
Recently, in some experimental models, it has been shown that caffeine inhibits a most important enzyme system—PDE (phos-pho-di-esterase)—that is involved in the process of learning and memory development. In reported experiments, caffeine impaired vision and memory components of the learning ability in the species involved in the experiment.
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