PART I
WHAT IS
THIS THING
CALLED “ME”?
CHAPTER 1
Brief Overview of the Entire Human Body
Six Levels of Organization
Atomic scale: the human body is written in the key of “C” (carbon)
In all, the “typical” adult organism of “average” build is an aqueous (“watery”), organic, complex assemblage of millions upon millions of different atoms. However, note from Table 1.1 that nearly 97 percent of one’s body weight consists of just four of them, i.e., oxygen (O), carbon (C), hydrogen (H), and nitrogen (N). The remainder includes at least 40 other elements—more than half of them (the entire right-hand column of Table 1.1) appearing in hardly measurable “trace” amounts (although they play crucial roles in affecting and controlling metabolic processes).
That oxygen and hydrogen should be so plentiful makes sense, considering that at least 60 percent or more of body weight exists as water—and salt water, at that. After all, we did originally come from the sea, hence the significant appearance and importance of sodium (Na) and chlorine (Cl) in Table 1.1 (Note: sodium chloride, NaCl, is sea salt). But why carbon and nitrogen? Why is carbon the “key note, C” from which all physiologic processes are “composed?” Why are we organic instruments? And what does nitrogen have to do with all of this?
Well, in the case of carbon, the short answer is that, of all the known chemical elements, this one is the most versatile, congenial, “sociable,” flexible, and outreaching—easy to deal with, and quite fond of and willing to interact with “others.” Thus, when it comes to choosing among all atomic candidates vying for the title of “most likely to succeed in producing complex life forms,” carbon is, by far, the clear winner! (For the long answer, see Schneck 2000a.)
As for nitrogen, observe that the air we breath is, by volume, about four-fifths nitrogen. It is not surprising, then, to learn that derived from this colorless, tasteless, odorless gas are some of the most important chemical elements required for the growth of all plants…and that nitrogen is also a necessary ingredient for the manufacture of animal tissue proteins. To address this latter role of nitrogen, we move on to the next level of anatomic organization.
ELEMENT | % OF BODY WEIGHT | ELEMENT | % OF BODY WEIGHT |
Oxygen | 63.000 | Antimony | Trace |
Carbon | 20.700 | Arsenic | Trace |
Hydrogen | 10.000 | Barium | Trace |
Nitrogen | 2.800 | Berylium | Trace |
Calcium | 1.575 | Boron | Trace |
Phosphorus | 1.050 | Cesium | Trace |
SUB-TOTAL | 99.125 | | |
Potassium | 0.247 | Chromium | Trace |
Sulfur | 0.207 | Cobalt | Trace |
Chlorine | 0.137 | Gold | Trace |
Sodium | 0.131 | Iodine | Trace |
Magnesium | 0.034 | Lithium | Trace |
Silicon | 0.026 | Manganese | Trace |
SUB-TOTAL | 99.907 | | |
Iron | 0.0050 | Mercury | Trace |
Fluorine | 0.0037 | Molybdenum | Trace |
Zinc | 0.0033 | Nickel | Trace |
Rubidium | 0.0005 | Radium | Trace |
Strontium | 0.0005 | Selenium | Trace |
Bromine | 0.0003 | Silver | Trace |
Lead | 0.0002 | Tin | Trace |
Copper | 0.0001 | Tungsten | Trace |
Aluminum | 0.0001 | Uranium | Trace |
Cadmium | 0.0001 | Vanadium | Trace |
SUB-TOTAL | 99.9208 | TOTAL | 100.0% |
Combinations of atoms: the molecular level of anatomical organization (musical “notes”)
The atoms of the human body are assembled into complex, polymeric, chemical chains that give birth to “the symphony of life.” Analogous to musical notes, these molecular chains are classified as follows.
Carbohydrates
Of what kinds of organic compounds is the human body “composed?” Well, for one thing, by adding water, H2O, to carbon, C, i.e., hydrating it, one can form compounds called, logically enough, carbohydrates. These include all starches and sugars (called polysaccharides ). In general, one can add “n” molecules of water (where “n” can take on integer number values, i.e., 1, 2, 3…) to “n” atoms of carbon, to form carbohydrates having the general chemical formula, (CH2O)n. These are photosynthesized in green plants from solar-energy-absorbing (hence, “photo-”) biochemical reactions, catalyzed by the green-colored enzyme chlorophyll (from the Greek chlōrós, meaning, “pale green,” and phýllon, meaning, “leaf”). The reactions combine carbon dioxide (CO2)n an...