G.HEMATOLOGY

= HEMATOLOGY  = =

__OVERVIEW __ In this portion of physiology we are beginning to learn the blood, the heart and circulation. This section covers the functions and components of the circulatory system, and the composition of blood. Functions of the circulatory system include transportation, regulation and protection. The components of the circulatory system are the cardiovascular system and lymphatic system. Composition of the blood includes what the make up of the blood is, the formed elements of blood, regulation of blood cells, blood typing, and blood clotting. **The functions of the circulatory system have been divided into three different areas:** **Transportation**-All of the substances needed for cellular metabolism are transported by the circulatory system. This category is divided furthermore into three types of transportation: respiratory, nutritive, and excretory. Respiratory is where the RBCs transport oxygen to the cells. Nutritive is the digestion system mechanically and chemically breaking down food for absorption. Excretory is when an excess of water, ions and wastes are carried to the kidneys for excretion in the urine. **Regulation**-The circulatory system contributes to hormonal and temperature regulation. In hormonal regulation the blood carries hormones from their site of origin to target cells and tissues. In the regulation of temperature, blood vessels are able to divert blood from superficial to deeper, or vise versa, when needed to conserve heat or cool the body. **Protection**-The circulatory system protects against blood loss from injury and against pathogens. Clotting protects the body from losing blood when the blood vessels are damaged. The WBCs (leukocytes) in the blood protect against disease- causing agents. Two systems of the body, the cardiovascular and lymphatic, are the **major components of the circulatory system**. The CV system is comprised of the heart and blood vessels where the lymph system is comprised of lymphatic vessels, and lymphoid tissues within the spleen, thymus, tonsils and lymph nodes. The heart is a four-chambered pump that pumps blood to the lungs and body cells, and it can pump about 5L of blood per minute. When pumped by the heart, the blood travels through blood vessels which for a tubular network for the transport of blood from the heart and back again. Arteries carry oxygenated blood away from the heart, where veins carry de-oxygenated back to the heart. As the blood is returned to the heart, some of the blood plasma leaves the CV system and enters the lymph system. The hydrostatic pressure of blood pushes some of the blood plasma out of the capillaries and into the connective tissue where it then enters the lymphatic vessels of the lymph system. The fluid then known as lymph is cleansed by lymph nodes before reentering the venous system returning to the heart. **The Composition of Blood** The blood contains plasma, erythrocytes (RBCs), different types of leukocytes (WBCs) and platelets. The blood cells and platelets are carried by the plasma which is a straw colored liquid. The plasma is made up plasma proteins, albumins, globulins (alpha, beta, and gamma globulins), and fibrinogen. Regulation of the osmolality of the blood plasma is regulated by osmoreceptors in the hypothalamus. The receptors detect when the blood plasma is more concentrated and releases ADH which makes the kidneys retain water until the osmolality of the plasma is returned to it's normal concentration. Erythrocytes are flattened, biconcave discs that do not have a nucleus and their function is the transportation of oxygen. The RBCs get their color from hemoglobin molecules. Hemoglobin is a molecule made of globin and heme, which contains iron. The heme combines with the oxygen in the lungs and in turn release oxygen to the tissues. Because leukocytes are almost invisible under a microscope they are stained. They are classified by their staining properties. There are WBCs that have granules in their cytoplams and are called granular leukocytes. This group contains the eosinophils, basophils, and neutrophils. WBCs without granules are called agranular leukocytes and the two types are lymphocytes and monocytes. There is also another type of cell in the blood called plasma cells which are derived from leukocytes. Platelets are the smallest of the elements of the blood and are fragments of megakaryocytes, which are formed in the bone marrow. They like the RBCs have no nucleus. Platelets have important functions in blood clotting. Blood cells are made by a process called hematopoiesis. Before birth this occurs in the liver, but after birth, the stem cells that eventually form blood cells are found in the bone marrow. Erythropoiesis, the formation of RBCs is regulated by erythropoietin which is secreted by the kidneys when blood oxygen levels are lowered Leukopoiesis, the formation of WBCs, is regulated by a variety of cytokines that stimulate the different stages of leukocyte development. The blood is "typed" by the different antigens and antibodies the blood contains. Type A blood has A-antigens on the RBCs and B-antibodies in the plasma amd visa versa for type B blood, it has B-antigens on the RBCs and A-antibodies in the plasma. This means that type A and type B blood are incompatible because the A-antibodies from the type B blood would be attracted to the A-antigens of the type A blood and cause agglutination. Agglutination is where the blood cells clump together and basically stop circulating and can be fatal. Blood clotting is a process which promotes hemostatis. When a blood vessel is injured, several hemostatic mechanisms are initiated. First the vessel constricts (vasoconstriction), next the platelets begin to attract to each other to form a platelet plug (which covers the injury of the blood vessel), and then clotting factors transforms fibrinogen into fibrin which penetrates, surrounds and strengthens the platelet plug decreasing blood loss from the injured blood vessel. __ESSENTIAL QUESTIONS __

Create a chart that shows the antigens and antibodies of the ABO +/- blood typing system. Also include on your chart, which blood types are compatible. The blue snowflake represents the anti-b antibody while the pink snowflake represents the anti-a antibody. You will notice that the antibodies that are present are the opposite of the type of red blood cell. However you will notice that the antigens present in the blood type is identical to the red blood cell type.



A- is compatible with O- and A- A+ is compatible with O-, O+, A-, and A+ B- is compatible with O- and B- B+ is compatible with O-, O+, B-, and B+ AB- is compatible with O-, A-, B-, and AB-, AB+ is compatible with O-, O+, A-, A+, B-, B+, AB-, and AB+. O- is compatible with O-. O+ is compatible with O- and O+.
 * __Here is a quick reiteration of the above chart:__**

What blood type is considered the universal donor and why? The universal donor is type O-. Everyone can receive type O - blood because it does not contain any A or B antigens. It is important to know if the individual's blood type is positive or negative (also known as the Rh factor) because a person who has a negative blood type can NOT (especially in child-bearing aged women) receive blood from a person with a positive Rh factor. A person with positive Rh blood contains a protein on the RBC's surface, known as an antigen and a person with Rh negative blood if given Rh positive blood will **develop** antibodies to this antigen and the blood will clump together (agglutinate) after the first exposure to Rh positive blood. Hence, a person with O negative blood is truly the universal donor because it contains no antigens on their cells and it can be given to anyone, including those with a negative Rh. What blood type is considered the universal recipient and why? The universal recipient is AB positive (AB negative needs blood from a person with Rh negative factor, but can receive any type of blood). Those with AB+ blood type can be given type A, B, and O blood because they contain all possible antigens on the surface of their RBC's and therefore will not develop antibodies that can cause complications. Describe what happens on the molecular level when blood types are not compatible (major crossmatch). If a patient is given blood that is incompatible to their blood type( see quick compatibility chart above), their body will have a reaction to the blood and the blood with "clump" together. What happens is each blood type has certain antigens or lack of antigens on their cell membranes. These antigens help the body detect themselves from foreign objects. Type A blood would have antigen A on its cell membrane and would have antibody B (meaning it is going to attack cells carrying the B antigen on its surface). Type B would have B antigens on its cell membrane and antibody A; type AB would have antigen A and antigen B on its cell membrane and would contain no antibodies; type O would contain no antigens on there cell membrane and would contain both antibody A and antibody B. Now these blood types may also be Rh+ or Rh-, which would mean Rh+ has the antigen and Rh- has than Rh antibody. What this means is if a person has A- blood and they were given A+ blood via a transfusion, the Rh antibody on the RBC's cell membrane will react to it as a foreign body and this will cause the cell to agglutinate (clump) together. This agglutination causes many issues because they can block the flow of blood in the smaller vessels and capillaries and also may cause RBC's to hemolysis (burst).

The two diagrams above demonstrate how the different blood types in blood and plasma are compatible. In the blood chart on the left you can see that while type O gives to everyone type AB can give to no one. The chart on the right is plasma compatibility diagram plasma from type AB can be given to A, B and O; plasma from types A and B can be given to O, while plasma from O cannot be given to anyone. [] link for blood type game.

**__SUMMARY __** The circulatory system is responsible for three areas: **1.) Transportation, 2.) regulation, and 3.) Protection.** The cardiovascular system and the lymphatic systems are both part of the circulatory system. Arteries, arterioles, capillaries, venules, and veins carry blood from the heart through the body to the different organs and cells and back to the heart again. The human bodies total blood volume is about 5L. Blood has formed elements and plasma which is the fluid part of the blood. media type="youtube" key="7J2uJv6EghM?fs=1" height="321" width="398" align="center"

The formed elements of blood include **erythrocytes** or red blood cells, **leukocytes** or white blood cells, and **platelets**. Erythrocytes carry oxygen throughout the body. Erythrocytes have a life span of about 120 days. Leukocytes include granular leukocytes and agranular leukocytes. Eosinophils, basophils, and neutrophils are all granular leukocytes. Granular leukocytes help get rid of foreign objects in the body and release heparin. Lymphocytes and monocytes are agranular leukocytes. Agranular leukocytes help to carry out phagocytosis and also produce antibodies. Platelets are very small pieces of megakaryocytes from the bone marrow. Platelets are very important in clotting. The platelets will release serotonin so that blood flow is reduced in the area of the clot. The erythrocytes in blood is how we can tell what blood type people are and if there are any antibodies in the blood which would prevent someone from getting certain units of blood if they need a blood transfusion. There are **A, B, and O types of blood and Rh negative blood and Rh positive blood**. It is simply amazing that we can take blood from one person and see what type of antigens are in it and transfuse it into a person that that blood is compatible with. See the chart above for the diffent blood types and each one of the blood types antigens and which types are compatible with which. The Rh factor in a mothers blood is also very important. If the mother has Rh negative blood and the baby has Rh positive blood the mother could start to attack the baby because the mother has produced Anti-D antibodies. Expecting mothers with Rh negative blood can get a shot to prevent this from happening. Plasma is the fluid part of the blood. It is made up of water and solutes such as ions, hormones, antibodies, and metabolites. Plasma proteins make up about 7%-9% of the plasma. There are three kinds of plasma proteins. Albumin is the most abundant. Albumin helps with the osmotic pressure. Gobulins carry lipids, and fibrinogen, which is converted to fibrin helps with the clotting process. After blood clots you are left with serum. __APPLICATION __

As a nurse I will be responsible to make sure that the patient is getting the proper blood type during a transfusion in order to save the patient’s life and minimize the risks to the patient’s life. I will have to verify the patients blood type through lab test results. I may have to draw the blood and send it to the lab or send the patient to the lab so that the blood can be drawn. Once the blood type has been confirmed i would verify that the blood being used for the transfusion is compatible with that of the patient.I would prep the patient for the transfusion and start the transfusion. The blood type game link above is a great fun way to learn what blood types are compatible.

When it comes to blood transfusions, my job as a nurse is to ensure the compatibility of the blood to my patient. If an emergency situation arose (like in the e.r) and typing of the patient's blood was not possible, I would know to ensure that the only type of blood the patient should get in this case is O- due to it having no antigens on its surface and it being compatible with all of the blood types. Most blood transfusions give whole blood which means it would just contain the RBC's, not the plasma. In the situation described above, if you were to give a person with a blood type other than O, RBC's along with the blood plasma, in high doses their body will have a reaction to the blood plasma and will agglutinate, just like in a transfusion reaction. Therefore, it is always best to know the patient's blood type to ensure the best possible outcome for the patient.

As a nurse I will be working with all kinds of patients and diagnoses. One of the diagnoses from this particular chapter that are examples of patients that I, as a nurse will be working with would be, Pernicious anemia which is an inadequate amount of vitamin B12, that is needed for RBC production, which is usually caused by atrophy of the granular mucose of the stomach, which normally secretes a protein called intrinsic factor. When the intrinsic factor is not present, the vitamin B12 obtained in a patients diet cannot be absorbed by instestinal cells. As a nurse, I need to know this information related to the patients diagnoses and understand why the patient is recieving IM injections of Vitamin B12, usually monthly and be able to explain the same knowledge with the patient.

Sources: Fox, Stuart Ira. (2009). //Human Physiology//. New York, NY: McGraw-Hill.

__CASE STUDY __ A Case of Thrombocytopenia **1. How and where are platelets produced in the body?** Platelets are fragments of megakarycytes which are cells found in the bone marrow. The fragments break off of the cytoplasm of the megakarycytes in the bone marrow to form the platelets which do not contain a nucleus. When the endothelium of a blood vessel wall is broken it exposes the collagen in the blood vessel wall and platelets are able to bind to the collagen. When the platelets stick to the collagen it activates the platelets to release adenosine diphosphate (ADP), serotonin and thromboxane A2. The ADP and thromboxane A released by the platelets attracts new platelets to the area of the broken blood vessel and makes the platelets sticky so they adhere to the platelets already stuck to the collagen. As more platelets stick the process repeats itself until there are enough platelets stuck to one another to form a platelet plug on the damaged area of the blood vessel. The platelets also have binding sites present where fibrin and fibrinogen join the platelets to strengthen the platelet plug. ** 3. Define thrombocytopenia and list the more common causes of this condition. ** Thrombocytopenia is a condition of the blood in which there is a low platelet count. Thrombocytopenia can occur as a result of a depletion of bone marrow which is common in patients that are undergoing chemotherapy for cancer. Other causes may be accelerated destruction of platelets possibly due to anti-platelet antibodies, infections, drugs or prosthetic heart valves, hemorrhage, blood transfusions that do not contain platelets, and anemia. **4. What are the potential consequences of a low platelet count?** When there is a low platelet count there is an increased risk of hemorrhage due to an inability of the blood to clot itself. This could be potentially very dangerous to the individual suffering from this disease as if they were to receive a serious injury they could hemorrhage severely and possibly lead to death. **5. What drugs have been associated with the development of thrombocytopenia?** Chemotherapy drugs are a common cause of thrombocytopenia. Some other drugs that may contribute are H2 blocking agents such as Zantac, Levaquin a blood thinner, streptomycin an antibiotic, quinidine to regulate the heart rate, aspirin, antihistamines, and digoxin. **6. How is thrombocytopenia treated in individuals diagnosed with the condition?** Since thrombocytopenia is generally caused by an underlying condition, physicians generally focus on treating the underlying condition to correct thrombocytopenia. In cases where chemotherapy is the cause of thrombocytopenia, thrombopoietin, a cytokin that stimulates the proliferation and maturation of megakaryocytes so they can form platelets, is used. **7. How might removal of the spleen (splenectomy) result in an increase in the number of circulating platelets?** After platelets are formed they live 5-9 days and are then destroyed by the spleen and liver. If the spleen is removed that takes away one of the organs that destroy the platelet cells. This could cause a higher number of circulating platelets as the liver may not be able to destroy enough platelets to properly regulate the platelet count. **8. What is Idiopathic Thrombocytopenic Purpura (ITP)?** Idiopathic Thrombocytopenic Purpura is a condition of low platelet count that has no known cause.
 * 2. Describe the role played by platelets in hemostasis.**

Sources: Fox, Stuart Ira. (2009). //Human Physiology//. New York, NY: McGraw-Hill. Pagana, PhD, RN, Kathleen Deska, Pagana, MD, FACS, Timothy J. (2009). //Mosby's Diagnostic and Laboratory Test Reference//. St. Louis, MO: Mosby Elsevier

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