Bovine biology series
Part - 15 Blood (2/2)
This remarkable fluid, the blood, is as integral to the mammalian body as are the primary organs....the brain, heart, liver and skeleton (spinal cord). If one were to submit a rather broad statement as to the necessity of this substance, than we might describe it as the fluid for maintaining homeostasis of the body proper. To be sure, we cannot long live without the blood maintaining the proper water, electrolyte, and gas balance.
There are other functions of blood, which I will examine in this concluding section.
Coagulation of the blood is important in order to maintain vascular integrity. Some genetic disorders, as those unfortunately carried by hemophiliacs and clinically expressed as failure to clot blood in a reasonable time frame, are part of our mammalian system. Hemophilia is caused by the blood plasma of afflicted animals lacking the factor necessary to cause blood to clot. The factor may carry several names but is generally considered a globulin protein substance. We remember, for instance, that vitamin K is involved with blood coagulation. This vitamin is responsible in part for the formation of prothrombin, one of the globulin proteins in blood (feeds high in Vitamin K: alfalfa, oats, wheat, rye and fishmeal products).
There is more to this than just coagulation, which is desirable of course during times of animal trauma....the rupture of a major or even minor blood vessel, especially a vein that is carrying blood (oxygen-rich) to a target tissue. You may ask why does blood not coagulate in the body? At what point does blood decide to clot?
Well these are very good questions. The nervous system is involved here. When trauma is sensed, the nerves signal a cascade of events, which begin the coagulation process. They include the conversion of fibrinogen, a blood protein, into fibrin, a thickening substance. The insoluble fibrin acts as a net and captures the larger blood cells, serving as a dam. The enzyme responsible for this conversion is thrombin. Calcium plays a major role in that this mineral is required for thrombin to work as an enzyme. Simply said, rations deficient in calcium impair the animals’ ability to clot blood.
Electrolyte regulation is a function of blood. The term electrolyte has something to do with electricity, and that has something to do with electrical charges, those pluses and minus of any magnetic system. The prefix electro is derived from the Greek word "elektor" which means beaming sun. The suffix lyte refers to the Greek word "lytos" which means solution.
The sum total of electrolytes in the blood may be termed the ionic composition. They consist of ions and other molecules, such as glucose and proteins, each carrying an electrical charge. A very large part of homeostasis is the maintenance of the ionic composition in balance. That is, the electrical charges are evenly distributed. The anions, such as chlorides, phosphors and sulfurs are balanced with the cations, sodium, magnesium, potassium and calcium.
The blood, of course, gives and takes these ions to and from the cells themselves and the interstitial space, the space not occupied by blood or cells.
For instance: sodium concentration is much higher in the blood plasma and interstitial space than inside the cell membrane. Chlorides are, conversely, just the opposite, finding a much greater concentration inside cells. Potassium is largely found in the cells by a factor of 34:1. Calcium, also a cation, is found largely in the blood and interstitial space by a factor of 2.5:1. Magnesium, a cation, is found in cells by a factor of 21:1. Proteins tend to concentrate in cells by a factor of 7:1; other organic substances, as a group, are concentrated in cells by a factor of 25:1.
As you can see this is not an easy or simple process, this homeostasis factor. But it may help by remembering that water is the solution and the carrier of a number of molecules and minerals. They routinely move between the blood volume, the interstitial space and the cellular world inside its membrane. Each has a function. Osmotic pressure, for instance, is the regulation of water inside and outside of the cells. Too much and they burst. Too little, and they do not function normally as they cannot receive nutrients from the blood. The primary osmotic regulators are the cation sodium, the anion chloride and the buffer sodium bicarbonate. Osmotic regulation is, therefore, related to water intake, ambient environmental temperature, body temperature, and diet. Here is something to keep in mind, and it is just one example of homeostasis:
We talk about excess potassium intake as a factor of management, primarily feeds that drive the ration content of potassium over required amounts. Well, the cows (and all mammals) absorb this potassium and it readily becomes a cation in the blood plasma volume. Because the cellular concentration of potassium is higher by a factor of 34:1, then as the blood volume increases just a little bit, the cellular concentration increases a large bit. This becomes extremely important because the cell pumps sodium out in exchange for potassium coming in. As potassium levels increase in the cell, sodium increases outside the cell. A typical response is an increased water intake by the animal in an attempt to maintain interstitial sodium levels, as well as an attempt to dilute the level of potassium found in the kidney ducts. So we have the case where hyperkalemia, a condition of too much potassium present in the body, will cause metabolic impairment including an increased water intake. In severe enough cases, death results as the heart suffers cardiac arrest, a condition in which the heart muscle can no longer function because the ionic imbalance of the blood plasma interferes with muscular contractions.
So this is just a glimpse of blood. We leave this liquid and look at another one, in many ways related. The lymph and the lymphatic system will be covered in the next two biology series.
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