Hematology

Hematology is the study of blood and diagnosing blood disorders, as well as the research of. This unit covered the many components and functions of blood, as well as what can be effected and result from problems within the blood.

THE MANY FORMED ELEMENTS OF BLOOD

Blood contains formed elements that are mixed together and carried in plasma (yellowish substance containing proteins, hormones, glucose for other cells, and carbon dioxide to take away from cells). The major elements are found within are erythrocytes, leukocytes and platelets. They function in transporting oxygen, immune defense and blood clotting.

ERYTHROCYTES (Red Blood Cells): These cells are by far the most numerous in the human body. They look like flatted disks and transport oxygen to different areas of the body. Each RBC contains hemoglobin molecules which contain iron.

LEUKOCYTES: These are referred to as the white blood cells. They have a smaller shape and can move easier to infection sites, while RBC's stay within the blood vessels. There are two different types of leukocytes called granulocytes and agranulocytes. Granulocytes are about twice the size of a RBC and have a visible cytoplasmic granule. They survive about 12 hours to 3 days. Different types of granulocytes include neutrophils (phagocytic), eosinophils (detoxify foreign substances, secrete enzymes to dissolve clots and fight parasitic infections), and basophils (release anticoagulant heparin to aid against thrombosis) Agranulocytes do not have a visible cytoplasm and can survive 100 to 300 days. Types include monocytes (also phagocytic), and lymphocytes (provide specific immune response).

PLATELETS: Smallest of the formed elements and are a cytoplasmic fragment coming from bone marrow. Platelets aid in blood clotting, and release serotonin (causing vasoconstriciton).



blood_90.jpg
http://www.davincialba.it/didattica/Blood_runs/testi/What's%20in%20blood.htmBLOOD TYPING
Blood types are a classifcation of blood based on different inherited antigens on the surface of red blood cells. They consist of the following phenotypes: A, B, O or AB. Then, blood is split into genotypes: A can be AA or AO, B can be BB or BO, O can only be O and AB can only be AB. To demonstrate, (an example taken from the text) an individual who is type A does not produce anti-A antibodies. However, they do make antibodies against the B antigen and conversly type B makes antibodies against the A antigen. An individual who is type AB has doesn't produce anti A or anti B antigens, therefore they have both in their plasma.


ABO_Blood_Types.jpg

http://www.biologycorner.com/anatomy/blood/notes_bloodtype.htmlTHE RH FACTORRH factor is named after the rhesus monkey, where the antigens were first discovered. The RH antigen is named D, often indicated as Rho(D). If the RH antigen is present in an individuals red blood cells, they are Rh postive (very common) and if not, they are Rh negative. The Rh factor is incredibly dangerous when a pregnant mom is Rh negative and is preparing to give birth to a Rh positive baby. This pregnacy should be normal and okay, but the next pregnancy (cies) will have complications because the mothers immune system will produce the anti-D antigens causing erythroblastosis fetalis leading to the fetus's death. The can be avoided by giving the mom a shot of RhoGAM within 72 hours after the Rh positive baby is born. This is a passive immunization which will inhibit the mother from producing the anti-D antibodies in her next pregnancies. Here is an illustration showing what happens with the different antibodies involving the Rh factor.

rH_factor.jpg
APPLICATION
As a nurse, I look at plenty of hematology reports as well as many other labs. Blood can tell us a lot about the patient's condition and possible disease process. If a person is complaining of increased fatigue, I could easily check their hematology report and look at their iron and hemoglobin values for a possibility of an iron deficiency (anemia). In the hospital setting, I can compare daily values to make sure that an infection is getting better by checking their different leukocytes. A high number can signal infection or leukemia while a low count can show that they have poor nutrition.
I also have to deal with blood transfusions. I cannot begin to describe how precious and sensitive blood types are and the safety considerations we must follow when administering blood to patients. If you give a patient the wrong type of blood, they can go into extreme shock, have severe adverse effects and possibly die. We never know how a patient will tolerate a blood transfusion, so the administration is VERY slow in the beginning. CASE STUDY"The Case of Iron Deficient Anemia"
1. Describe the structure of a molecule of hemoglobin and explain the role played by iron in the transport of oxygen. The hemoglobin structure is an assembly of four globular protein subunits. Each subunit is composed of a protein chain which is arraged into a set of alpha-helix structural segments connected together in a globin fold arrangement. Without enough iron, your body can't produce enough hemoglobin, a substance in RBC's that enables them to carry oxygen.
2. How is iron stored and transported in the body? Iron is mostly stored in the body in the hemoglobin but 30 percent is stored in the bone marrow, spleen and liver. During absorption, iron is combined with oxgen and transported through the plasma portion of blood and from there is used in the production of hemoglobin.
3. What is iron deficiency anemia and how frequently does it occur? Iron deficiency anemia is really common and is due to insufficient iron. Without enough iron, your body can't produce enough hemoglobin to enable RBC's to carry oxygen.
4. What are the most common causes of IDA? Most common causes are blood loss, lack of iron in diet, inability to absorb iron and pregnancy.
5. Why are women more prone to IDA than men? Women lose blood monthly during menstration making them at greater risk than men for developing IDA.
6. What do the RBC's indicate and what diagnostic tests are used for IDA? RBC size and color would be smaller and paler if the patient had anemia. Diagnostic tests would include checking your hematocrit and your hemoglobin (which would both be lower than normal if patient had anemia).
7. How is IDA treated and prevented? IDA is treated and prevented by eating iron rich foods (oysters, spinach, nuts) and taking iron supplements.



IDA