Hematology and Immunology

Hematology and Immunology • Hematology is the medical specialty that studies the anatomy and physiology of the blood and uses diagnostic tests, medical and surgical procedures, and drugs to treat blood diseases.

Hematology and Immunology • Immunology is the medical specialty that studies the anatomy and physiology of the lymphatic system and uses diagnostic tests, medical and surgical procedures, and drugs to treat lymphatic and immune response diseases.

Figure 6-1 Lymphatic system

Anatomy and Physiology (cont’d) • The Blood – Contains blood cells, blood cell fragments, water, and other substances (proteins, clotting factors, etc.) – Transports oxygen, carbon dioxide, nutrients, and waste products – Contains cells that also function as part of the immune system

Anatomy and Physiology (cont’d) • The Lymphatic System – Consists of the lymphatic vessels, lymph fluid, lymph nodes, lymphoid tissues, and lymphoid organs – Forms a pathway throughout the body that is separate from that of the cardiovascular system that contains the blood – Defends the body against microorganisms and cancerous cells

Anatomy of the Blood • Plasma – Clear, straw-colored liquid (about 90% water) that makes up 55% of the blood. – The formed elements of the blood (erythrocytes, leukocytes, and platelets) are suspended in the plasma.

Anatomy of the Blood (cont’d) • Plasma (cont’d) – Contains substances the body produces itself such as: albumin, bilirubin, hormones, complement proteins, and clotting factors. – Contains creatinine and urea, which are waste products of cellular metabolism.

Figure 6-2 Plasma

Anatomy of the Blood (cont’d) • Erythrocytes – Most numerous of the formed elements in the plasma – Red blood cell that is a round, somewhat flattened, red disk – Unique because, unlike other body cells, they have no cell nucleus when they are mature

Figure 6-3 Hematopoiesis.

Figure 6-4 Erythrocytes Andrew Syred/Photo Researchers, Inc.

Anatomy of the Blood (cont’d) • Erythrocytes (cont’d) – Contain hemoglobin, a red, iron-containing molecule that binds to oxygen molecules to form oxyhemoglobin. – Hemoglobin carries oxygen from the lungs to every cell in the body, and carries carbon dioxide from the cells back to the lungs. – Hematopoiesis, the process by which all blood cells are formed, occurs in the red marrow of long or flat bones.

Anatomy of the Blood (cont’d) • Erythrocytes (cont’d) – Very immature cells are known as stem cells. – Erythrocyte stem cells mature to become erythroblasts and then normoblasts.

Anatomy of the Blood (cont’d) • Erythrocytes (cont’d) – Do not have a nucleus, so they cannot divide or repair themselves. – Last 120 days before they begin to deteriorate. – Specialized cells (macrophages) break down erythrocytes’ hemoglobin into heme and globins.

Anatomy of the Blood (cont’d) • Erythrocytes (cont’d) – Iron stripped from heme molecules is stored in the liver and the spleen; the remainder of heme molecules is converted to bilirubin. – Bilirubin plays an important role as an antioxidant, protecting body cells from damage by free radicals.

Anatomy of the Blood (cont’d) • Leukocytes – White blood cells that include five types of cells (neutrophils, eosinophils, basophils, lymphocytes, and monocytes) – Can be identified by the presence or absence of granules in their cytoplasm and the shape of their nucleus

Anatomy of the Blood (cont’d) • Leukocytes (cont’d) – Leukocytes with large granules in their cytoplasm are categorized as granulocytes, which include neutrophils, eosinophils, and basophils. – Leukocytes with few or no granules in their cytoplasm are categorized as agranulocytes, which include lymphocytes and monocytes.

Anatomy of the Blood (cont’d) • Neutrophils – Most common leukocyte, making up 40 to 60% of leukocytes in blood – Categorized as granulocytes – Nucleus has many segments or lobes, so they are also known as polymorphonucleated leukocytes (PMNs), polys, segs, or segmenters

Anatomy of the Blood (cont’d) • Neutrophils (cont’d) – Develop in the red marrow – Engulf and destroy bacteria (phagocytosis) – Live only a few days or even just a few hours if they are actively destroying bacteria

Figure 6-5 Neutrophil

Anatomy of the Blood (cont’d) • Eosinophils – Make up just 1 to 4% of leukocytes – Categorized as granulocytes; also known as eos – Nucleus has two lobes – Develop in the red marrow – Engulf and destroy foreign cells (pollen, animal dander, etc.) – Release chemicals that kill parasites

Figure 6-6 Eosinophil

Anatomy of the Blood (cont’d) • Basophils – Least common leukocyte, making up 0.5 to 1% of leukocytes – Categorized as granulocytes; also known as basos – Nucleus has more than one lobe – Develop in the red marrow – Release histamine at the site of tissue injury – Release heparin, an anticoagulant

Figure 6-7 Basophil

Anatomy of the Blood (cont’d) • Lymphocytes – Make up 20 to 40% of leukocytes. – Categorized as agranulocytes and are the smallest leukocytes; they are also known as lymphs. – Nucleus is round and nearly fills the cell. – Some lymphocytes live for just a few days, while others live for many years.

Anatomy of the Blood (cont’d) • Lymphocytes (cont’d) – Begin development in red marrow; some become B cells or natural killer cells; others migrate to the thymus to become T cells – Present in the blood and lymph nodes; destroy viruses and produce antibodies

Figure 6-8 Lymphocyte

Anatomy of the Blood (cont’d) • Monocytes – Make up 2 to 4% of leukocytes – Categorized as agranulocytes and are the largest leukocytes; also known as monos – Have a large amount of cytoplasm, and nucleus is large and kidney bean shaped – Develop in the red marrow

Anatomy of the Blood (cont’d) • Monocytes (cont’d) – Are phagocytes that engulf and destroy microorganisms, cancerous cells, dead leukocytes, and cellular debris. – Monocytes in the lymph nodes, intestine, liver, pancreas, thymus, spleen, bone, and skin are known as macrophages.

Figure 6-9 Monocyte

Table 6-1 Leukocyte Types and Characteristics

Table 6-1 (continued) Leukocyte Types and Characteristics

Anatomy of the Blood (cont’d) • Thrombocytes – Different from other blood cells because they are only cell fragments – Active in the blood-clotting process – Begin in the red marrow as stem cells that then become megakaryoblasts, and then mature into megakaryocytes, a very large cell – Cytoplasm of the megakaryocyte breaks away at the edges to form cell fragments (thrombocytes) that are released into the blood

Anatomy of the Blood (cont’d) • Blood Type – Most important blood types are the ABO and Rh blood groups – ABO blood group contains A, B, AB, and O antigens

Table 6-2 ABO Blood Group

Anatomy of the Blood (cont’d) • Blood Type (cont’d) – Rh blood group has 47 different antigens – Rh is positive when antigens are present on erythrocytes – Rh is negative when antigens are not present on erythrocytes

Figure 6-10 A unit of blood Shout Pictures/Custom Medical Stock Photo, Inc.

Physiology of Blood Clotting • Platelet aggregation―Thrombocytes form clumps to decrease blood loss • Coagulation―Blood clot forms • Hemostasis―Cessation of bleeding • When clotting factors in the plasma are activated to form a blood clot, the fluid portion of plasma that remains is known as serum.

Figure 6-11 Blood clot Susumu Nishinaga/Photo Researchers, Inc.

Table 6-3 Blood Clotting Factors

Table 6-3 (continued) Blood Clotting Factors

Anatomy of the Lymphatic System • Lymphatic Vessels, Lymph, and Lymph Nodes – Lymphatic vessels are similar in structure to blood vessels, but with several important differences. – Begin as tiny lymphatic capillaries in the tissues.

Anatomy of the Lymphatic System (cont’d) • Lymphatic Vessels, Lymph, and Lymph Nodes (cont’d) – End in ducts that empty into large veins in the neck. – Tissue fluid enters a lymphatic capillary and becomes lymph, the fluid that circulates through the lymphatic system.

Anatomy of the Lymphatic System (cont’d) • Lymphatic capillaries have large openings in their walls that allow microorganisms and cancerous cells to enter. • Lymphatic capillaries become larger lymphatic vessels that bring lymph to the lymph nodes. • Valves keep the lymph flowing in one direction.

Anatomy of the Lymphatic System (cont’d) • Lymphoid Organs (cont’d) – Grouped together in chains in areas where there is a high risk of invasion by microorganisms or cancerous cells. – Lymphatic vessels end at ducts in the thoracic cavity: right lymphatic duct and thoracic duct. – Both lymphatic ducts then empty into large veins in the neck.

Figure 6-12 Lymphatic system

Anatomy of the Lymphatic System (cont’d) • Lymphoid Tissues – Contain lymphocytes and macrophages that are active in the immune response • Tonsils and adenoids in the oral cavity • Appendix and Peyer’s patches in the small intestine

Anatomy of the Lymphatic System (cont’d) • Lymphoid Organs – Thymus is located within the mediastinum and helps lymphoblasts mature into T lymphocytes – Spleen is located on left side of abdominal cavity and is the largest organ in the lymphatic system – Spleen removes old erythrocytes from the blood

Anatomy of the Lymphatic System (cont’d) • Lymphoid Organs – Spleen also acts as storage area for whole blood, which is released into the circulatory system during times of danger or injury

Diseases and Conditions • Blood – Blood dyscrasia – Hemorrhage – Pancytopenia – Septicemia

Diseases and Conditions (cont’d) • Erythrocytes – Abnormal red blood cell morphology – Anemia • • • • •

Aplastic anemia Folic acid deficiency anemia Iron deficiency anemia Pernicious anemia Sickle cell anemia

Figure 6-13 Microcytic, hypochromic erythrocytes Joaquin Carillo Farga/Photo Researchers, Inc.

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Figure 6-14 Sickle cell Eye of Science/Photo Researchers, Inc.

Figure 6-15 Sickle cells in a capillary

Diseases and Conditions (cont’d) • Erythrocytes (cont’d) – Anisocytosis – Poikilocytosis – Polycythemia vera – Thalassemia – Transfusion reaction

Diseases and Conditions (cont’d) • Leukocytes – Acquired immunodeficiency syndrome (AIDS) – Leukemia – Mononucleosis – Multiple myeloma

Figure 6-16 Human immunodeficiency virus Chris Bjornberg/Photo Researchers, Inc.

Figure 6-17 Acute lymphocytic leukemia Peres/Custom Medical Stock Photo, Inc.

Diseases and Conditions (cont’d) • Thrombocytes – Coagulopathy – Deep venous thrombosis (DVT) – Disseminated intravascular coagulation (DIC) – Hemophilia – Thrombocytopenia

Figure 6-20 Deep venous thrombosis

Diseases and Conditions (cont’d) • Lymphatic System – Graft-versus-host disease (GVHD) – Lymphadenopathy – Lymphedema – Lymphoma • Hodgkin’s lymphoma • Non-Hodgkin’s lymphoma

– Splenomegaly – Thymoma

Figure 6-19 Lymphadenopathy Custom Medical Stock Photo, Inc.

Diseases and Conditions (cont’d) • Autoimmune Disorders – Diabetes mellitus, type 1 – Graves’ disease – Hashimoto’s thyroiditis – Inflammatory bowel disease – Multiple sclerosis

Diseases and Conditions (cont’d) • Autoimmune Disorders (cont’d) – Myasthenia gravis – Psoriasis – Rheumatoid arthritis – Scleroderma – Systemic lupus erythematosus

Laboratory and Diagnostic Procedures • Blood Cell Tests – Blood type – Complete blood count (CBC) with differential – Peripheral blood smear

Table 6-4 Complete Blood Count (CBC) with Differential

Table 6-4 Complete Blood Count (CBC) with Differential

Laboratory and Diagnostic Procedures (cont’d) • Coagulation Tests – Activated clotting time (ACT) – Partial thromboplastin time (PTT) – Prothrombin time (PT)

Laboratory and Diagnostic Procedures (cont’d) • Other Blood Tests – Blood chemistries – Ferritin

Figure 6-20 Blood chemistry analyzer Alvis Upitis/Jupiter Images – PictureArts Corporation/Brand X Pictures – Royalty Free

Laboratory and Diagnostic Procedures (cont’d) • Other Blood Tests (cont’d) – Human immunodeficiency virus (HIV) tests • ELISA―First screening test done for HIV • Western blot―Used to confirm a positive ELISA and make a diagnosis of HIV infection • Viral RNA load test―Measures tiny amounts of HIV RNA and monitors progression of the disease and response to antiretroviral drugs

Laboratory and Diagnostic Procedures (cont’d) • Other Blood Tests (cont’d) – Human immunodeficiency virus (HIV) tests (cont’d) • p24 antigen test―Detects the protein p24 in HIV • CD4 count―Used to monitor the progression of the disease and response to antiretroviral drugs

– Total iron-binding capacity (TIBC)

Laboratory and Diagnostic Procedures (cont’d) • Saliva Test – OraSure • Quick screening test that is done in the doctor’s office or clinic. It uses the same technology as the ELISA blood test.

Laboratory and Diagnostic Procedures (cont’d) • Serum Tests – Electrophoresis – Monospot

Laboratory and Diagnostic Procedures (cont’d) • Urine Tests – Bence Jones protein – Schilling test

Laboratory and Diagnostic Procedures (cont’d) • Radiologic Procedures – Color flow duplex ultrasonography – Lymphangiography

Medical and Surgical Procedures • Medical Procedures – Bone marrow aspiration – Phlebotomy – Vaccination

Figure 6-21 Phlebotomy Getty Images – Photodisc-Royalty Free

Medical and Surgical Procedures (cont’d) • Blood Donation and Transfusion Procedures – Blood donation – Blood transfusion

Medical and Surgical Procedures (cont’d) • Blood Donation and Transfusion Procedures (cont’d) – Bone marrow transplantation (BMT) – Plasmapheresis – Stem cell transplantation

Figure 6-22 Stem cell Dr. Yorgos Nikas/Photo Researchers, Inc.

Medical and Surgical Procedures (cont’d) • Surgical Procedures – Lymph node biopsy – Lymph node dissection – Splenectomy – Thymectomy