9.1 pp. Leukocytes and Granulocytes: Module 9

• Leukocytes and granulocytes are types of blood cells.
• Module 9 covers Guyton-34, 35 and McCance 9.
• Module 9 learning objectives include describing the hematologic system, understanding blood cell roles in hemostasis, and evaluating hematologic system disturbances.

White Blood Cells (WBCs)

• There are approximately 7000 WBCs per microliter of blood.
• Neutrophils constitute 62% of WBCs.
• Eosinophils make up about 2.3% of WBCs.
• Basophils account for 0.4% of WBCs.
• Monocytes comprise 5.3% of WBCs.
• Lymphocytes represent 30% of WBCs.
• Polymorphonuclear leukocytes (granulocytes) include neutrophils, eosinophils, and basophils.
• Granulocytes and monocytes protect against invading organisms.
• Myelocytes and lymphocytes go through genesis.

WBC Lifespan

• WBCs consist of granulocytes, monocytes and lymphocytes.

Infection Defense

• Neutrophils and macrophages are essential for attacking and destroying harmful agents.
• Movement of these cells occurs through diapedesis and amoeboid motion.
• Chemotaxis guides WBCs to areas with bacterial/viral toxins, inflamed tissue, cabinet complex reaction products and plasma clotting reaction products.
• Increased Margination and permeability help defend against infection.

Infection Defense: Phagocytosis

• Neutrophils typically phagocytize 3 to 20 bacteria before dying.
• Macrophages can phagocytize up to 100 bacteria before death.
• Phagocytic vesicles become digestive vesicles containing bactericidal agents.
• Antibodies and chemotactic substances are factors in infection defense.
• Phagocytosis process involves receptors, pseudopod formation, lysosomes, and phagolysosomes.
• Digestion happens through exocytosis.

Reticuloendothelial System

• This system comprises monocytes, mobile macrophages, fixed tissue macrophages, and specialized endothelial cells in bone marrow, spleen, and lymph nodes.
• Tissue macrophages are present.
• Lymph node macrophages are located in germinal centers, subcapsular sinus, and medullary sinuses.
• Alveolar macrophages are in the lungs.
• Kupffer cells are in the liver.
• Macrophages are also present in the spleen, bone marrow, and the G.I. tract.

Inflammation

• Tissue injury can cause secondary changes in surrounding uninjured tissue.
• Tissue products such as histamine, bradykinin, serotonin, prostaglandins, and complement system reaction products are responsible for these reactions.
• Inflammation leads to the formation of a walled-off area.
• Macrophages and neutrophils respond rapidly to injury.
• Neutrophilia develops within hours.
• Monocytes from the blood also invade the inflamed tissue.
• Control of macrophage response involves more than two dozen factors.
• Pus is a product of inflammation.

Other Types of WBCs

• Eosinophils account for 2% of blood leukocytes.
• Basophils have functions similar to mast cells and closely work with them.

Leukopenia

• Leukopenia involves the bone marrow producing very few WBCs.
• Possible causes include exposure to X-rays, gamma rays, drugs or chemicals containing benzene or anthracene nuclei.
• Drugs like chloramphenicol, thiouracil, and barbiturates can cause leukopenia.
• Without treatment, death from leukopenia may occur in less than a week.

Leukemia

• Leukemia is characterized by uncontrolled WBC production.
• Types of leukemia include lymphocytic and myelogenous.
• Leukemia occasionally produces partially differentiated cells.
• Leukemia cells are frequently bizarre and undifferentiated.
• Undifferentiated cells often indicate more acute leukemia.