PowerPoint Lecture Presentations prepared by Bradley W. Christian, McLennan Community College C H A P T E R 16 Innate Immunity: Nonspecific Defenses of the Host
Host Response to Disease Resistance- ability to combat disease Susceptibility- vulnerability to disease Innate immunity: defenses against any pathogen; rapid, present at birth Adaptive immunity: immunity or resistance to a specific pathogen; slower to respond, has memory component
Three Levels of Defense 1. Physical barriers 2. Natural, non-specific mechanisms 3. Immune response
Big Picture: Immunity
Natural Barriers Skin- epidermis and dermis Sebum, fatty acids, lysozyme Mucous membranes- moist layer of epithelial cells and connective tissue Mucus, ciliary escalator
Natural Mechanisms Innate- present from birth Non-specific Priming not required
Blood Plasma- the fluid component Formed elements- cells and platelets
Blood Cells Erythrocytes- red blood cells (RBC) Transport blood gases and some nutrients
8 µm average diameter
Blood Cells Leukocytes- white blood cells (wbc) 1 o function is defense against infection Five separate lineages
Formed Elements in Blood Cells and cell fragments suspended in plasma Erythrocytes (red blood cells) Leukocytes (white blood cells) Platelets Created in red bone marrow stem cells via hematopoiesis
Figure 16.4 Hematopoiesis.
Formed Elements in Blood Granulocytes are leukocytes with granules in their cytoplasm that are visible with a light microscope Neutrophils: phagocytic; work in early stages of infection Basophils: release histamine; work in allergic responses Eosinophils: phagocytic; toxic against parasites and helminths
Table 16.1 Leukocytes (White Blood Cells)
Formed Elements in Blood Agranulocytes are leukocytes with granules in their cytoplasm that are not visible with a light microscope Monocytes: mature into macrophages in tissues where they are phagocytic Dendritic cells: found in the skin, mucous membranes, and thymus; phagocytic Lymphocytes: T cells, B cells, and NK cells; play a role in adaptive immunity
Table 16.1 Leukocytes (White Blood Cells)
white blood cell red blood cell plasma platelet white blood cell
Big Picture: Immunity White blood cell (WBC) counts measure leukocytes in the blood High WBC counts may indicate bacterial infections, autoimmune diseases, or side effects of medications Low WBC counts may indicate viral infections, pneumonia, autoimmune diseases, or cancers
Big Picture: Immunity Plasma White blood cells Red blood cells NORMAL RANGES AND PERCENTAGES for men and nonpregnant women White blood cell count: 5,000 10,000 WBCs per cubic millimeter (mm 3 ) or 5.0 10.0 x 10 9 WBCs per liter. Neutrophils: 60% to 70% Lymphocytes: 20% to 25% Monocytes: 3% to 8% Eosinophils: 2% to 4% Basophils: 0.5% to 1%
Phagocytosis Endocytotic ingestion Cells, cellular debris, and other particulates A sequence of events
The Mechanism of Phagocytosis Chemotaxis Chemical signals attract phagocytes to microorganisms Adherence Attachment of a phagocyte to the surface of the microorganism Ingestion Opsonization: microorganism is coated with serum proteins, making ingestion easier Digestion Microorganism is digested inside a phagolysosome
Adhesion Toll-like receptors (TLRs) on host cells attach to pathogen-associated molecular patterns (PAMPs) TLRs bound to PAMPs induce the release of cytokines from the host cell that regulate the intensity and duration of immune responses
Inflammation Function: 1. Destroy and/or remove 2. Confine and limit spread 3. Repair damaged tissue
Characteristic Manifestations redness heat pain swelling loss of function
Inflammation 1) Vasodilation and increased vascular permeability Inflammation activates acute-phase proteins by the liver that cause vasodilation and increased permeability of blood vessels Histamine Kinins Prostaglandins - intensfier Leukotrienes Cytokines
Stages of Inflammation 1. Vasodilation and increased vascular permeability Vasoactive amines stimulate these phenomena
Figure 16.8a
Figure 16.8b, steps 1 3
Stages of Inflammation 2. Phagocyte migration and activity Margination sticking of phagocytes to blood vessels in response to cytokines at the site of inflammation Diapedesis phagocytes squeeze through endothelial cells.
Figure 16.9b The process of inflammation. Blood vessel endothelium Monocyte Bacterium RBC Margination phagocytes stick to endothelium. Diapedesis phagocytes squeeze between endothelial cells. Macrophage Neutrophil Phagocytosis of invading bacteria occurs.
Stages of Inflammation 3. Tissue repair Only after all harmful substances are removed
Figure 16.8d
Types of Inflammation Acute- short duration, no scar Chronic- longer duration, scarring
Fever
Antimicrobial Proteins Transferrin- Iron-binding proteins Interferons (IFN)- a family of proteins IFN-α and IFN-β protect neighboring cells from viral infections
Figure 16.15 - Overview
Antimicrobial Proteins Complement- a set of proteins with cascading activity Multifunctional Enhance phagocytosis and inflammation Attack complex makes holes in cells
Figure 16.9 - Overview (1 of 5)
Figure 16.9, steps 1 5 (2 of 5)
Figure 16.9 (3 of 5)
Figure 16.9 (4 of 5)
Figure 16.9 (4 of 5)
Figure 16.9 (5 of 5)
Figure 16.11 - Overview
Figure 16.12 - Overview
Figure 16.11, step 1
Figure 16.11, step 2
Figure 16.11, step 3
Figure 16.13
Figure 16.11 - Overview