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Enero 21, 2012

Chapter 16: Blood


The average adult has about 4-5 liters in female and 5-6 liters in male of blood living inside of their body, coursing through their vessels, delivering essential elements, and removing harmful wastes. Without blood, the human body would stop working.

Blood is the fluid of life, transporting oxygen from the lungs to body tissue and carbon dioxide from body tissue to the lungs. Blood is the fluid of growth, transporting nourishment from digestion and hormones from glands throughout the body. Blood is the fluid of health, transporting disease fighting substances to the tissue and waste to the kidneys.

Blood is a type of connective tissue, consisting of cells and cell fragments surrounded by a liquid matrix. The cells and cell fragments are the formed elements, and the liquid is the plasma. The formed elements make up about 45%, and plasma makes up about 55% of the total blood volume. Blood makes up about 8% of the total weight of the body.


Plasma is a pale yellow colored, clear liquid that is 91% water; 7% proteins; and 2% other substances, such as ions, nutrients, gases, and waste products. It is also an essential ingredient for human survival.

It might seem like plasma is less important than the blood cells it carries. But that would be like saying that the stream is less important than the fish that swims in it. You can't have one without the other.

Besides water, plasma also contains dissolved salts and minerals like calcium, sodium, magnesium, and potassium. Microbe-fighting antibodies travel to the battlefields of disease by hitching a ride in the plasma.
Without plasma, the life-giving blood cells would be left floundering without transportation. Never underestimate the importance of plasma.

Plasma proteins are proteins found in the blood plasma, the clear, protein-rich fluid which is left behind when platelets, red blood cells, and white blood cells are removed from the blood. These proteins play a number of important roles in the human body, and levels of plasma proteins are sometimes evaluated in a laboratory analysis to gather information about a patient's general health and specific health issues which a patient may be experiencing. Plasma proteins make up around 7% of the total blood volume, with levels which can fluctuate at times.
Plasma proteins include albumin, globulins, and fibrinogen.
·         Albumin acts as a transporter and a regulator of osmotic pressure
·         Globulins are involved in transport and immune processes
·         Fibrinogen is primarily involved in blood clotting
Activation of clotting factors results in the conversion of fibrinogen into:
o   Fibrin is a threadlike protein that forms blood clots
    Serum is plasma without the clotting factors



About 95% of the volume of the formed elements consist of red blood cells (RBCs), or erythrocytes; white blood cells (WBCs), or leukocytes; and platelets, or thrombocytes.



The process of blood cell production is called hematopoiesis.

When a blood vessel is severely damaged, blood clotting, or coagulation, results in the formation of a blood clot. A blood clot is a network of threadlike protein fibers, called fibrin, that traps blood cells, platelets, and fluid.
The formation of a blood clot depends on a number of proteins, called clotting factors. Most clotting factors are manufactured in the liver, and many of them require vitamin K for their synthesis. In addition, many of the chemical reactions of clot formation require Ca2+ and the chemicals released from platelets. Low levels of vitamin K, low levels of Ca2+, low numbers of platelets, or reduced synthesis of clotting factors because liver dysfunction can seriously impair the blood-clotting process.
1.    The extrinsic pathway of clotting starts with thromboplastin, which is released outside of the plasma in damaged tissue.
2.    The intrinsic pathway of clotting starts when inactive factor XII, which is in the plasma, is activated by coming into contact with a damaged blood vessel.
3.    Activation of the extrinsic or intrinsic clotting pathway results in the production of activated factor X.
4.    Activated factor X, factor V, phospholipids, and Ca2+ from prothrombinase.
5.    Prothrombin is converted to thrombin by prothrombinase.
6.    Fibrinogen is converted to fibrin by thrombin.
7.    Thrombin activates clotting factors, promoting clot formation and stabilizing the fabrin clot.



My blood type is O, what’s yours? If you don’t know, well, here’s how.
Purchase a blood type testing kit. If you or someone you know happens to work in a medical setting, see if you can get your hands on one of these tests for free.
·         Dispense one drop of your blood to each field on the test card. Use a sterilized needle. The fields contain antibodies, which will provoke a reaction with antigens on your red blood cells.
·         Use a new toothpick for each field to mix the blood with the impregnation, creating an about dime-sized smear.
o   If you have blood type A, clumping will appear in following fields: anti-A
o   If you have blood type B, clumping will appear in the field: anti-B
o   If you have blood type AB, clumping will appear in fields anti-A, anti-B
o   If you have blood type O, no clumping will appear.

Landsteiner observed two distinct chemical molecules present on the surface of the red blood cells. He labeled one molecule "A" and the other molecule "B." If the red blood cell had only "A" molecules on it, that blood was called type A. If the red blood cell had only "B" molecules on it, that blood was called type B. If the red blood cell had a mixture of both molecules, that blood was called type AB. If the red blood cell had neither molecule, that blood was called type O.

If two different blood types are mixed together, the blood cells may begin to clump together in the blood vessels, causing a potentially fatal situation. Therefore, it is important that blood types be matched before blood transfusions take place. In an emergency, type O blood can be given because it is most likely to be accepted by all blood types. However, there is still a risk involved.

A person with type A blood can donate blood to a person with type A or type AB. A person with type B blood can donate blood to a person with type B or type AB. A person with type AB blood can donate blood to a person with type AB only. A person with type O blood can donate to anyone.

A person with type A blood can receive blood from a person with type A or type O. A person with type B blood can receive blood from a person with type B or type O. A person with type AB blood can receive blood from anyone. A person with type O blood can receive blood from a person with type O.

Because of these patterns, a person with type O blood is said to be a universal donor. A person with type AB blood is said to be a universal receiver. In general, however, it is still best to mix blood of matching types and Rh factors.

To understand better ABO Blood Group, here’s a video that would help you:



Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein. The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.

If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-).

This Rh factor is connected to your blood type. For example, your blood may be AB+ which means that you have type AB blood with a positive Rh factor. Or, you might have O- blood which means that you have type O blood with a negative Rh factor.

It is particularly important for expectant mothers to know their blood's Rh factor. Occasionally, a baby will inherit an Rh positive blood type from its father while the mother has an Rh negative blood type. The baby's life could be in great danger if the mother's Rh negative blood attacks the baby's Rh positive blood. If this happens, an exchange transfusion may save the baby's life. The baby's blood can be exchanged for new blood that matches the mother's.

End of Chapter 16








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