Ph: An important requirement for the ECF is that it be neither too acid
nor too alkaline. Degree of acidity is measured on a scale of pH units.
Pure water, which is neutral, that is, neither acid nor alkaline, has a
pH of 7. Acid substances are substances which produce more H+ ions
than are found in pure water. They have pH values of less than 7. Alkaline
(or basic) substances are substances which combine with H+ ions, thus leaving
fewer than are found in pure water. They have pH values greater than 7.
We know that both OH- ions and HCO3- ions combine with H+ ions.
OH- + H+ <> H2O
and
HCO3- + H+ <> H2CO3 <> H2O + CO2
Thus, when sodium hydroxide (NaOH) or sodium bicarbonate (NaHCO3)
is dissolved in water, a basic solution (alkaline) results. The pH scale
is a logarithmic one : each unit on the pH scale represents a tenfold increase
or decrease in the concentration of H+ ions over the next lower or higher
unit. For example, a solution with a pH of 5 is ten times more acid than
a solution of pH 6 (has a concentration of H+ ions ten times greater).
Most living cells are extremely sensitive to changes in the pH
of their ECF (extracellular fluid). The pH of human plasma is usually maintained
at a value between 7.34 and 7.44. If these limits should be greatly exceeded
(below pH 6.8 or above pH 7.8), serious illness or death would follow.
Fortunately, our plasma is well supplied with substances called "buffers",
that act to prevent any sudden shift in pH. The proteins found in blood
plasma act as buffers. If the pH should start to decrease (violent exercise
or holding the breath will cause this), the proteins combine with the new
H+ ions, thus keeping the pH constant. If the pH should start to rise,
the proteins release H+ ions to the ECF, thus restoring the original condition.
Hormones help control the actions of the proteins under changing pH conditions.
The plasma proteins thus serve as a homeostatic mechanism for maintaining
a constant pH in the ECF.
Blood plasma also contains bicarbonate ions (HCO3-) which serve
in the same capacity. In the presence of an increased concentration of
H+ ions (and thus a decrease in pH), the following occurs: HCO3- + H+ <>
H2CO3 .
When the H2CO3 reaches the lungs, it decomposes into carbon
dioxide (which passes into the air) and neutral water: H2CO3 <>
H2O + CO2 . Thus the danger of to many H+ ions in the ECF is neatly avoided.
Temperature. Another important characteristic of the ECF is its
temperature. Protists have no control over the temperature of their ECF.
It is simply a a function of the climatic conditions around them. This
is generally true of plants, invertebrate animals, and the so-called cold
blooded (or poikilothermic) vertebrates: the fishes, amphibians,
and reptiles. In some cases, however, the organisms have a certain degree
of control over the temperature of their ECF. When the temperature
in a bee hive becomes too high, the workers begin cooling the hive by bringing
in water and fanning the air with their wings. Fanning brings in fresh
air and speeds evaporation of the water, which is itself a cooling process.
Goldfish have been shown to seek water in a preferred temperature
range. In fact the goldfish have been trained in the laboratory to trigger
a cold water valve when the water gets to warm.
Many lizards also exert considerable control over the temperature
of their ECF at least for the periods when they are active. Basking in
the sun enables a lizard to raise its body temperature to the preferred
range for its species even though the temperature of the surrounding air
may be considerably cooler. When the air temperature becomes quite high,
the lizards can still maintain their preferred temperature by evaporating
water from their tongue (panting) and retreating to shady locations.
It is among the birds and mammals, that we find the strictest
control over the temperature of their ECF. Birds and mammals are able to
maintain their temperature within very narrow limits despite wide fluctuations
in the temperature of the surrounding air. For this reason, they are often
called "warm-blooded", or better, homeothermic. A healthy human is capable
of maintaining the temperature of his ECF within a degree or so of
98.6 F (37.5 C) at rest or during violent exercise, in warm or cold surroundings.
As a closing note, it seems that recent research is showing that fungi were present on land as far back as 1.3 billion years, and plant life on land as far back as 700 million years. This means that the beginning of an oxygen atmosphere started much longer ago that had been previously thought. Of course we know that the oxygen atmosphere was a prerequisite for animal life to develop.
---the end---
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
