Thursday, July 2, 2009

Part one: the cell

This is part one of a series of non-consecutive posts which are intended to explain in the simplest of terms the nature of a disease called diabetes mellitus. Although I will often grossly oversimplify in these posts, I will promise to still be factual. I will also try to present it in smaller chunks than my usual long posts.
Your body is made up of tiny little building blocks called "cells." Inside cells, the construction and demolition work of running your body takes place. There are different kinds of cells, such as muscle cells and nerve cells. Your body's blueprint, a substance called "dna," is stored in your cells.

In order to do their work of carrying on the life processes of your body, the cells need raw materials and an energy source. They also need their trash picked up. The delivery of raw materials and the collection of waste are taken care of by the bloodstream.

The raw materials are chemicals. These chemicals come primarily from the food you eat. Molecule chains are constructed or broken down, as needed. This is the constant work that goes on in the cell. When the cell is constructing, the process is called "anabolic activity." When the cell is taking molecules apart to use their parts, the process is called "catabolic activity." In both cases, heat is given off as a byproduct of the chemical reaction and the "burning" of the fuel. The overall process of either building something or taking something apart is called "metabolism."

Cells need fuel to carry on these life processes. This fuel is called "glucose." Glucose is an end-product of the digestion of food substances called "carbohydrates."** Digestion means the breaking down of complex molecules into their simpler components. Eventually, they are simple enough to enter the bloodstream.

Cells won't allow just any substance to enter. In order to cross the cell's membrane, the substance must be recognized by the cell. Glucose, for example, must be attached to a special substance the cell recognizes, a hormone called "insulin." Then the cell will allow the glucose to pass through a special portal in its membrane. Without insulin, the cell won't allow glucose inside, even though the cell might need glucose very badly.

If the glucose can't get into the cell, it keeps building up in the blood until dangerous life-threatening levels are reached. At the other end, the cell is starving in the midst of plenty, and will malfunction and eventually die. This hormone called insulin is very important to us all. It is one of the things produced in a large gland called the "pancreas."
**Although glucose is normally obtained from the digestion of carbohydrates, the body can also make glucose out of protein, though much less efficiently. This means if you deprive your diet of carbohydrates, you body will begin breaking down protein to make glucose. Your body doesn't make glucose out of fat. If you don't eat protein either, then your body will begin breaking down its own protein: skeletal muscles and organ tissue. When your body does this you are in a condition called starvation. When the organs can no longer function, you will die.
Next: exactly what is diabetes?


  1. According to wikipedia (which I consulted because the concept that we can't get glucose from fat failed my smell test - my father was a biologist) fat can be converted to glycol and fatty acids. Glycol can be converted to glucose in the liver - which is good or our extra fat stores would never be reducible.

    It is, however, much simpler (takes less effort) to get glucose from carbs than any other method.

  2. It's interesting, isn't it, that when you study, and it applies to almost any subject really, you tend to learn in self contained sections. The result is you can't, or don't, always join the dots. Thank you, dot-joiner extraordinaire. :)

  3. Yes, Stephanie. First, thank you for letting me wait to comment on your comment until we were all through, since my goal was simplicity.

    Approximately 5% of the fat we eat is digested into a substance called glycerol. The other 95% is fatty acids. This substance called glycerol is absorbed by the liver and then used mostly to help breakdown existing glucose into energy through a process called glycolysis. Yes, through gluconeogenesis, actual glucose can also be painstakingly made by the liver. Again, used almost immediately for energy (the liver's energy, mostly.) The liver's stored glucagon can, of course, be converted into glucose and dumped into the bloodstream if your blood-sugar drops enough. A safety measure. This convoluted process is OF COURSE germane to the blood sugar level being kept constant and adequate, but is not really the prime source of energy for the body's other cells. I was trying to concentrate on carbohydrate in this post, because that's where almost 100% of the body's glucose comes from under normal circumstance, so you can perhaps forgive me for not including the above in the post. Perhaps I should have. But I thank you for mentioning this since I also said in the post I wanted to be accurate. It was a case of not wanting to go into a side trip which I thought would confuse rather than edify. But you are right and I am sorry I didn't at least say something like, "Fat contributes a tiny amount of glucose also, which can be used in an emergency." You are ALWAYS right. Heh. But I was also, perhaps, right to leave it out or the main post. Thanks again, K?

    Anyway, you are absolutely right, except when you said our fat would never be used otherwise.

  4. @A. - Hmmm. Dot-joiner, eh? I will take that as a compliment. Although it probably isn't. :)



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