2-1 Introduction to Hematology

What anticoagulant is used for most hematological tests?

Ethylenediamintetraacetic acid (EDTA) is the anticoagulant that is most used in the hematology laboratory.

Name an inherited hematological disease.

Hemophilia is an inherited disease, people who have it have bleeding problems either because they lack one of the coagulation factors required for blood to clot or because one of the coagulation factors is defective. In other inherited hematological diseases, patients can have abnormal hemoglobin function, such as that caused by the abnormal structure of hemoglobin in sickle cell anemia.

How does hematology QA differ from QA methods in clinical chemistry?

In clinical chemistry, certified standards for substances such as glucose or sodium are easily obtained, in a hematology lab, stable standards are not as widely available.

What tests are usually included in a complete blood cell count (CBC)?

Red blood cell count White blood cell count Hemoglobin Hematocrit Red blood cell indices White blood cell differential count Platelet count or platelet estimate Evaluation of blood cell morphology

Erythrocyte

red blood cell; RBC

Oxyhemoglobin

the form of hemoglobin that binds and transports oxygen

Deoxyhemoglobin

the hemoglobin formed when oxyhemoglobin releases oxygen to tissues

Plasma

the liquid portion of blood in which the blood cells are suspended; the straw -colored liquid remaining after blood cells are removed from anticoagulated blood

Hemoglobin ( Hgb)

the major functional component of red blood cells that is the oxygen-carrying molecule

Leukocyte

white blood cells; WBC

Hematopoietic stem cell

an undifferentiated bone marrow cell that gives rise to blood cells; also called hemopoietic stem cells

Discuss the uses of stem cells.

The possible uses for stem cells are to treat disease, injuries, and genetic disorders—these are called cell-based therapies.

Thrombocyte

a blood platelet

Vein

a blood vessel that carries deoxygenated blood from the tissues to the heart

Artery

a blood vessel that carries oxygenated blood from the heart to the tissues

Anticoagulant

a chemical or substance that prevents blood coagulation

Leukemia

a chronic or acute disease involving unrestrained increase in leukocytes

Granulocyte

a white blood cell containing granules in the cytoplasm; any of the neutrophilic, eosinphilic, or basophilic leukocytes

EDTA

ethylendiaminetetraacetic acid; an anticoagulant commonly used in hematology

Stem cell

an undifferentiated cell

White blood cell (WBC)

blood cell that functions in immunity; leukocyte

Red blood cell (RBC)

blood cell that transports oxygen (O2) to tissues and carbon dioxide (CO2) to the lungs; erythrocyte

Hemopoiesis

the process of blood cell formation and development; hematopoiesis

Hemostasis

the process of stopping bleeding, which includes clot formation and clot dissolution

Hematology

the study of blood and the blood-forming tissues

Systemic circulation

the system of blood vessels that carries blood from the heart to the tissues and back to the heart

Cardiopulmonary circulation

the system of blood vessels that circulates blood from the heart to the lungs and back to the heart

What is meant by a secondary or acquired hematological condition?

Abnormalities in blood cells can also occur because if a condition or disease originating in another organ system. For example, abnormal appearing red blood cells can be present in patients with severe hypertension or renal failure because the cells become damaged as they circulate through small blood vessels. In infectious mononucleosis, a viral disease, lymphocytes develop an "atypical" appearance that can be observed when a stained blood smear is examined microscopically. Blood cells can be affected by treatments on medications, aspirin inhibits platelet function, and chemo and radiation can affect blood cell precursors in the bone marrow and therefore inhibit blood cell production.

Name the three major types of blood vessels and explain the differences among them.

Arteries are thick-walled, elastic, and muscular and ate the strongest types of blood vessels. Capillaries are the smallest of the blood vessels and connect the smallest arterioles with the smallest veins, called venules. Veins carry deoxygenated blood from the capillaries to the heart. They expand into venules and then into veins that eventually converge to larger and larger vessels and from the largest vein, the vena cava. Arteries carry oxygenated blood and veins carry deoxygenated blood.

What two types of blood specimens are used for most hematological tests?

Both capillary and venous blood can be used for most routine hematological procedures.

What is the most primitive blood cell called?

Hematopoietic Stem Cell-an undifferentiated bone marrow cell that gives rise to blood cells; also called hemopoietic stem cell.

Where are the red blood cells (RBC--erythrocytes) produced?

In fetuses blood cells are made in the liver, as the fetus begins to get older, the bone marrow begins to take over. In adults, the cellular elements of blood are produced in the bone marrow.

Name five components of plasma.

Plasma is more the 90% water; the remainder is dissolved solids, including proteins such as albumin and antibodies, lipids, carbohydrates, amino acids, hormones, an electrolytes.

What are the three groups of formed elements in the blood? What are the functions of each group?

The cellular elements of blood are called blood cells. These include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (also called thrombocytes). The primary function of red blood cells is to transport O2 to the tissues and CO2 to the lungs. The hemoglobin molecules perform this function. White blood cells are associated with immunity or defense against infection, foreign substances, or tumor cells. White blood cells perform most of their functions in the tissues and use blood as a means of transport from one part of the body to another. There are five types of WBC's present in normal blood, neutrophils, basophils, eosinophils, lymphocytes, and monocytes, they each have their own function, but all have to do with immunity. Platelets help stop bleeding by forming a plug in injured or damaged vessel walls, they also release chemicals and enzymes that are important in another stage of hemostasis, the coagulation cascade.

Name the five types of white blood cells found in the blood and state which are granulocytes.

There are five types of WBC's present in normal blood, neutrophils, basophils, eosinophils, lymphocytes, and monocytes. The neutrophils, basophils, and eosinophils are called granulocytes because of granules present in the cell cytoplasm.

What are the common routine Hematology tests that are done?

They are: complete blood count (CBC), white blood differential, Erythrocyte sedimentation rate (ESR), microhematocrit test, and prothrombin test.

Which specific blood component is responsible for oxygen exchange?

This function is performed by the hemoglobin molecules, the major component of the RBC's.

Where are the white blood cells (WBC) produced?

WBC are produced in the bone marrow and also in secondary lymphoid tissue such as the spleen and lymph nodes.

Complete blood count (CBC)

a commonly performed grouping of hematological tests

Anemia

a condition in which the red blood cell count or hemoglobin level is below normal; a condition resulting in decreased oxygen-carrying capacity of the blood

Platelet

a formed element in circulating blood that plays an important role in blood coagulation; a small disk-shaped fragment of cytoplasm derived from a megakaryocyte; a thrombocyte

Megakaryocyte

a large bone marrow cell from which platelets are derived

Capillary

a minute blood vessel that connects the smallest veins and serves as an oxygen exchange vessel

Arteriole

a small branch of an artery leading to a capillary

Venule

a small vein connecting a capillary to a vein