Electrolytes and The
Acid/Base Balance

Section 4.2
(Published Mar.5, 2024)

This section builds upon the previous potential of hydrogen section, and after describing two basic categories of matter - light and dark.

It is the body's respiratory and renal systems (renal, meaning associated with the kidneys) which play the largest role in blood-pH homeostasis. The respiratory system removes CO₂ from the body, and the renal system removes excess hydrogen ions, which are ultimately expelled through the urine.

Most of the by-products created via our body's metabolic processes, slant towards the acidic side. Because of this bias, the body compensates through certain pH buffering systems. There are a number of these systems within our body, a couple of which we will be reviewing shortly.

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Due to the heavy mass of an atom's nucleus as compared to its associated electrons, I surmise that the early scientific models which evolved around atomic structures - began with the nucleus and worked their way out from there. Especially since the weights of elements, are a major cornerstone within the science of chemistry.

The relatively light and illusive electrons which can scurry about an atom's perimeter, are typically more difficult to study than the atom's heavy nucleus. Although science has done a tremendous job by adding electrons to the puzzle of atomic structures - where exactly these electrons are at any one time.... no one really knows.

Electrons continually move about, and do not have a predetermined (or presumed) position within atomic structures like the protons and neutrons do. The "modern" 20th century models of atomic structures that focus upon electrons, reside under the guise of mathematical probabilities.

The concept of pH which we reviewed within the last section, is a basic construct for all biological organisms. We will now venture forward, and review certain chemically based concepts, which nicely build upon the prior pH section. 

As we continue, don't worry about memorizing chemical formulas and the like, but note the negative ions within each of the formulas. These anions and polyanions, represent an overabundance of electrons, and are basically the "free" electrons, which can energetically be attracted to another chemical structure.

4.2.1 Defining Electrolytes

A fundamental principle behind electrolytes, is that pure water does not conduct electricity. As neutrally charged electrolytes (net-neutral) are added to an aqueous solution, they disassociate into both positive and negative ions. It's these ions that make the resulting solution electrically conductive. 

There are a good number of soluble acids, bases, and salts, which are chemical-compounds, that may also be classified as electrolytes. However, under the study of human physiology - there's just a small number of electrolytes which we normally need to be concerned about. These common electrolytes are: bicarbonate, calcium, chloride, magnesium, phosphate, potassium, and sodium.

As each of these electrolytes dissolve into a solution, the ions which commonly arise are: hydrogen carbonate (HCO₃^-), calcium (Ca²⁺), chloride (Cl^-), magnesium (Mg²⁺), hydrogen phosphate (HPO₄ ^2-),  potassium (K⁺), and sodium (Na⁺).

In addition to the preceding, there is another definition for electrolytes, and that is this:

Electrolytes are minerals which when dissolved, create either negative or positive ions.

Certain minerals which are not normally used within bodily processes and yet can still be easily dissolved, might better fall under this definition than the first.

4.2.2 Acid/Base Balance

There are highly tuned systems within our blood and cells, which have been created to properly buffer and balance pH levels. Basically, these systems dampen any dramatic variation of pH.

Proteins work well for this, as proteins can carry either negative or positive charges, and can act as ions. However, for our purposes herein, we will focus upon two major pH buffering systems, which rely upon chemical compounds.

The bicarbonate and phosphate ions which will be looking into are both anions, and therefore store excess electrons. Hence, they tilt more towards the "light" side of matter than the "dark" side of matter.

4.2.3 Bicarbonate Anion

The bicarbonate ion (HCO₃^-) is a polyatomic anion having an elementary charge of -1.

The bicarbonate ion is a byproduct of certain electrolytes. Perhaps the most important physiological function of bicarbonate, is that it's a major component of our blood's (primary) pH buffering system.

Bicarbonate also contributes to the digestive process. Bicarbonate is injected into the duodenum’s lumen (small intestine's cavity) from both the pancreas and duodenum-wall glands. In so doing, this raises the pH of the intestine's contents whilst processing, and protects the intestines from harmful acid released from the stomach. Importantly, bicarbonate also serves to regulate the digestive process.

A familiar example of bicarbonate, is the one which occurs within household baking soda. Baking soda has the chemical formula NaHCO3. It's a salt comprised of both a sodium cation (Na+) and a bicarbonate anion (HCO3−). Although baking soda is a compound that's not normally associated with human physiology, since it easily dissolves in water and creates ions - it is also classified as an electrolyte.

4.2.4 The Blood's pH Buffering System

As I recently stated, bicarbonate is used for the blood’s pH buffering system. It's function is to buffer the waste product CO₂ (carbon dioxide) that continually gets released into the bloodstream from cells. The intracellular process which creates this CO₂ is referred as cellular respiration.

This buffering system which utilizes bicarbonate, manages our blood's CO₂ until it can be properly disposed of through the lungs. This integrate system maintains our blood's pH level between the narrow band of 7.35 - 7.45. It resists any radical change to blood pH, and maintains the status quo.

As carbon dioxide (CO₂) gets released into the blood, it quickly dissolves and forms carbonic acid (H₂CO₃). Once carbon dioxide becomes trapped in this state, the pH-buffering-system takes over from there.

The homeostatic relationship for this buffering system, is represented by the following formula.

 H₂CO₃ + H₂O  <=======>  HCO₃^-  + H₃O⁺

Note that the negatively charged anion of the formula, is our bicarbonate (HCO₃^-).

I've yet to mention the ion H₃O⁺, which is the cation hydronium. As the formula shows, it's basically a single water molecule (H₂O) with one extra proton.

Anion Gap Test

An anion gap test, is a blood-test used by the medical profession in order to determine if the pH buffering system is functioning appropriately. This test underscores the physiological importance of blood-serum bicarbonate.

This anion gap test may also be used to diagnose the condition of metabolic acidosis and certain conditions related to diabetes. Either a dramatic loss of bicarbonate or a rise of fixed acids - can result in metabolic acidosis. Serum concentrations of bicarbonate, chloride, sodium, and perhaps even potassium; are compared against each other during these tests.

4.2.5 Phosphate Anions

The phosphates have a few ionic species which are basically derivatives of orthophosphoric acid (H3PO4), which is a weakly-acidic electrolyte. Phosphate ions are byproducts of certain electrolytes, orthophosphoric acid being one of them.

Phosphates are common within many of our natural foods, particularly meat and seafood. Phosphates are also added to many of our processed foods. I see here, that on a box of hot-chocolate - phosphate was added in the form of dipotassium phosphate.

Note that too much phosphate in the blood is not a good thing, and can cause serious health issues (refer to hyperphosphatemia).

Where we learned earlier that bicarbonate anions are an important facet of the blood's pH buffering system..... take note that phosphates are an important facet of intracellular pH buffering. As a direct consequence, bicarbonates are abundant within our blood, and phosphates are abundant within our cells. 

Listed below, are the phosphate ionic-species, each with a differing charge potential. Each unique species has a different number of "extra" electrons.

• Di-hydrogen phosphate, H₂PO₄^-    (anion)
• Hydrogen phosphate, HPO₄^2-        (polyanion)
• Phosphate, PO₄^3-                              (polyanion)

Analogous with the concept of light and dark categories, we see that these ions are certainly biased towards the "light" side of matter. Respectively, we see that these phosphate ions have either one, two, or three extra electrons.

I believe that the primary two species of ions that are used for buffering cell-pH, are di-hydrogen phosphate (H₂PO₄^-) and hydrogen phosphate (HPO₄^2-).

  H₂PO₄^-   <=========>   HPO₄^2-  +  H⁺

In this case, the di-hydrogen phosphate is the weak acid, and the hydrogen phosphate is its conjugate weak base. 

Approximately eighty-five percent of our body's phosphate is stored within the bones, fifteen percent is stored within soft-tissue cells, and a fractional amount within the blood. Both phosphate and calcium within our bones and teeth, are integral to building the bone-mineral hydroxyapatite, Ca₅(PO₄)₃(OH).

Within our cells, phosphate is used  to create chain-like molecules such as ADP, ATP, DNA and RNA. Phosphate is also used for building cellular-membranes within phospholipids. 

As I stated, phosphate is used for creating ATP (adenosine triphosphate). ATP is the common energy-currency molecule that's both created, stored, and used for fuel, within each of our cells.

Interestingly, the concentration of ATP anions within a neutral-pH solution is dominated by the ionic species of ATP⁴⁻. To a smaller degree, this same neutral-pH solution also contains the species ATP^3-. As we see here, both of these ATP ionic species which are abundantly used for energy storage - are highly polyanionic.

Phosphate Drugs

Targeted for health and longevity, phosphate drugs are commonly prescribed for osteoporosis. As a group, these  medications are referred to as bisphosphonates; both oral and intravenous versions are available. Current examples of these drugs are shown below.

• alendronate (Fosamax).
• etidronate (Didrocal)
  
• risedronate (Actonel).
• zoledronic acid (Aclasta)

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