micro chapter 14 Host defenses
Lymphatic Vessels
1. Along the lines of blood vessels 2. Similar to thin-walled veins 3. High numbers in hands, feet, and around the areola of the breast 4. Flow of lymph is in one direction only- from extremities toward the heart 5. Lymph is moved through the contraction of skeletal muscles through which the lymphatic ducts wend their way
Fever
1. An abnormally elevated body temperature 2. FUO: cause of fever is unknown 3. Initiation of fever - pyrogen sets the hypothalamic "thermostat" to a higher setting a. Muscles increase heat production b. Peripheral arterioles decrease heat loss through vasoconstriction - Pyrogens can be exogenous or endogenous - Macrophages release two potent pyrogens : 1. interleukin 1 - communication btw wbc (endogenous) 2. tumor necrosis factor (TNF)
Miscellaneous Lymphoid Tissue
1. Bundles of lymphocytes lie at many sites on or just beneath the mucosa of the gastrointestinal and respiratory tracts 2. Tonsils 3. Breasts of pregnant and lactating women 4. GALT in the intestinal tract - Appendix - Peyer's patches 5. Mucosal-associated lymphoid tissue (MALT) 6. Skin-associated lymphoid tissue (SALT) 7. Bronchial-associated lymphoid tissue (BALT)
The Inflammatory Response
1. Cascade of events 2. injured tissues release chemicals (chemotactic) 3. selectins appera on endothelial capillaries (stickey surface) 4. integrins on neutrophils help them attach to endothelial integrins receptors. this is called margination. 5. mast cells release histamine 6. histamine causes vasodilation, and openings occur in capillaries 7. neutrophils change shape and squeeze thru capillaries. this is call extravastion/diapedesis 8. neutrophils & others are attracted to site by chemotactic 9. ingest & destroy invading bacteria
Lymphatic System
1. Compartmentalized network of vessels, cells, and specialized accessory organs 2. Transports lymph through a system of vessels and lymph nodes 3. Major functions - Provide an auxiliary route for the return of extracellular fluid to the circulatory system proper - Act as a drain-off system for the inflammatory response - Render surveillance, recognition, and protection against foreign materials
Vascular Changes: Early Inflammatory Events
1. Controlled by nervous stimulation, chemical mediators, and cytokines (released when damage to tissue) released by blood cells, tissue cells, and platelets in the injured area 2. Vasoactive mediators affect the endothelial cells and smooth muscle cells of blood vessels. 3. Chemotactic factors (chemokines) affect white blood cells 4. Cause fever, stimulate lymphocytes, prevent virus spread, and cause allergic symptoms 5. Arterioles constricted at first but quickly vasodilation takes place
Erythrocytes
1. Develop from stem cells in the bone marrow 2. Lose their nucleus just prior to entering circulation 3. Transport oxygen and carbon dioxide to and from the tissues
Edema
1. Exudates: the fluid that escapes through gaps in the walls of postcapillary venules 2. Contains plasma proteins, blood cells, and cellular debris 3. May be clear (serous) or may contain red blood cells or pus (accumulated phagocytes, cellular debris, and pyogenic bacteria) 4. Diapedesis: how WBCs leave the blood vessels and into tissue spaces 5. chemotaxis: the tendency of WBCs to migrate in response to a specific chemical stimulus
Platelets
1. Formed elements in circulating blood 2. Not whole cells 3. Function primarily in hemostasis and in releasing chemicals for blood clotting and inflammation
Phagocytosis: Cornerstone of Inflammation and Specific Immunity
1. General activities of phagocytes - Survey the tissue compartments and discover microbes, particulate matter, and injured or dead cells - Ingest and eliminate these materials - Extract immunogenic information (antigens) from foreign matter
Complement Cascade
1. Initiation - this is the variation 2. Amplification and cascade 3. Polymerization 4. Opsonization, Inflammation and formation of Membrane attack complex (MAC) (many different proteins. ring, hollow center, makes a hole, things leak out and cell lyses). Purpose for each of these? (36)
Lymphocytes
1. Key cells in the third line of defense and the specific immune response (notice nonself) 2. When stimulated by antigens, transform into activated cells that neutralize and destroy that foreign substance 3. B cells - Humoral immunity: protective molecules carried in the fluids of the body - Produce specialized plasma cells which produce antibodies/immunoglobulins 4. T cells - cell-mediated immunity: T cells modulate immune functions and kill foreign cells (confirm infection & allow start of response
Late Reactions of Inflammation
1. Long-lived inflammation attracts a collection of monocytes, lymphocytes, and macrophages to the reaction site 2. Macrophages clear pus, cellular debris, dead neutrophils, and damaged tissue 3. B lymphocytes produce antibodies/immunoglobulins 4. T lymphocytes kill intruders directly 5. Late in the process the tissue is repaired or replaced by connective tissue (scar)
Lymphatic Fluid
1. Lymph 2. Plasma-like liquid formed when certain blood components move out of blood vessels into the extracellular spaces and diffuse or migrate into the lymphatic capillaries 3. Composition parallels that of plasma, but without red blood cells
Lymphoid Organs and Tissues
1. Lymph nodes 2. Thymus 3. Spleen 4. Gut-associated lymphoid tissue (GALT) 5. Tonsils 6. Loose connective tissue framework that houses aggregations of lymphocytes
Complement
1. Over 30 blood proteins that work in concert to destroy bacteria and certain viruses **Cascade reaction AKA as domino effect 2. Three different pathways that all yield similar end results Classical pathway Lectin pathway Alternative pathway
The Inflammatory Response: A Complex Concert of Reactions to Injury
1. Reaction to any traumatic event in the tissues 2. Classic signs and symptoms Rubor (redness) Calor (warmth) Tumor (swelling) Dolor (pain) 3. Fifth symptom has been added: loss of function
Body Compartments that Participate in Immune Function
1. Reticuloendothelial system (RES) ****Provides a passageway within and between tissues and organs 2. Spaces containing extracellular fluid (ECF) 3. Bloodstream 4. Lymphatic system
nonspecific chemical defenses
1. Sebaceous secretions and specialized glands- antimicrobial 2. Lysozyme in tears and saliva (break apart peptido) 3. Lactic acid and electrolyte concentrations of sweat 4. Skin's acidic pH and fatty acid content 5. HCl in the stomach 6. Digestive juices and bile in the intestine 7. Semen- antimicrobial chemical 8. Acidic pH in the vagina
Spleen
1. Similar to a lymph node except it filters blood instead of lymph 2. Filters pathogens from the blood
Thymus
1. Site of T-cell Maturation 2. Thymus originates in the embryo 3. High rates of activity and growth until puberty 4. Shrinks gradually through adulthood 5. Thymic hormones help thymocytes develop specificity to be released as mature T cells
Lymph Nodes
1. Small, encapsulated, bean-shaped organs 2. Usually found in clusters along lymphatic channels and large blood vessels of the thoracic and abdominal cavities 3. Major aggregations: axillary nodes, inguinal nodes, cervical nodes
immune system is responsible for:
1. Surveillance of the body 2. Recognition of foreign material 3. Destruction of entities deemed to be foreign 4. White blood cells must distinguish self from nonself cells 5. Evaluates cells by examining markers (proteins/sugars) on their surfaces
Second Line of Defense
1. generally nonspecific but supports & interacts w/specific immune response Inflammation Phagocytosis Interferon Complement
plasma
1. hundreds of different chemicals 2. Components = water (92%), albumin, globulins, immunochemicals (antibodies), fibrinogen, hormones, nutrients, dissolved gases and waste products
benefits of fever
1. inhibits multiplication of temp.sensitive MO 2. impedes the nutrition of bacteria by reducing the availibility of iron 3. increases your metabolism & stimulates immune reactions & naturally protective physiological processes
Chief Functions of Inflammation
1. mobilize & attract immune components to site of injury 2. set in motion mechanisms to repair tissue damage & localize & clear away harmful substances 3. detroy microbes & block further invasion
Three main types of phagocytes
1. neutrophils 2. monocytes 3. macrophages
phagocytosis
1. something on surface that triggers attachment 2. phagosome 3. lysosome - organelle containing lysozyme 4. lysozyme - breaks apart peptidoglycan 5. protease - break apart proteins
Monocytes
Agranulocyte 1. Discharged by bone marrow into bloodstream, live as phagocytes for a few days, then differentiate into macrophage 2. "Fixed" (lungs, liver, bronchii) and wandering 3. Responsible for - Many specific and nonspecific phagocytic and killing functions - Processing foreign molecules and presenting them to lymphocytes - Secreting biologically active compounds that assist, mediate, attract, and inhibit immune cells and reactions Dendritic cells (we'll learn more in specific immunity)
Interferon
Antiviral Cytokines and Immune Stimulants 1. Interferon (IFN): involved against viruses, other microbes, in immune regulation and intercommunication 2. Three major types: alpha, beta & gamma 3. All three classes produced in response to viruses, RNA, immune products, and various antigens 4. Bind to cell surfaces and induce changes in genetic expression (can tell cell what to transcribe & translate) 5. Can inhibit the expression of cancer genes and have tumor suppressor effects
BALT
Bronchial-associated lymphoid tissue
Origin, Composition, and Functions of the Blood
Circulatory system - Circulatory system proper - Lymphatic system
Benefits of Edema and Chemotaxis
Dilutes toxic substances Fibrin clot can trap microbes and prevent further spreading Phagocytosis occurs immediately (not dependent on antigen signal)
Eosinophils
Granulocyte Attack and destroy large eukaryotic pathogens Also involved in inflammation and allergic reactions
Basophils
Granulocyte Parallel eosinophils in many actions
Neutrophils
Granulocyte phagocytosis starts inflammation
Chemicals Released by Damaged Cells: leukotrienes
Increased permeability of blood vessels, phagocytic attachment Stimulate contraction of smooth muscle
Chemicals Released by Damaged Cells: prostaglandins
Intensify histamine and kinin effect Powerful stimulants of inflammation of pain
Immune defenses: Body compartments
Intracellular - digesting Extracellular Lymphatic Cerebrospinal Circulatory
MALT
Mucosal-associated lymphoid tissue
Chemicals Released by Damaged Cells: Histamine
Produced by mast cells Vasodilation, increased permeability of blood vessels (allows cells to escape ex. monocytes)
SALT
Skin-associated lymphoid tissue
cell-mediated immunity
T cells modulate immune functions and kill foreign cells (confirm infection & allow start of response
extravastion/diapedesis
WBC/neutrophils change shape and squeeze thru capillaries
endotoxin
a bacterial toxin that is not ordinarily released. endotoxin is composed of a lipopolysaccharide complex of GN bacteria - are exogenous pyrogens ex. E. coli
pyrogen
a substance that causes a rise in body temperature
exotoxin
a toxin that is secreted and acts upon a specific cellular target are released by bacteria
pyogenic bacteria
ability to make pus
classical pathway
activated by antibody. C3 cleaved, results in 1. opsonization =ability to phagosize (like putting handles on a capsule) 2. inflammation = (mast cell releases histamine) 3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Alternative pathway
activated by factors BDP (recognize a complex on microbes results in 1. opsonization =ability to phagosize (like putting handles on a capsule) 2. inflammation = (mast cell releases histamine) 3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Lectin pathway
activated by mannose on surface results in 1. opsonization =ability to phagosize (like putting handles on a capsule) 2. inflammation = (mast cell releases histamine) 3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Vasoactive mediators
affect the endothelial cells and smooth muscle cells of blood vessels.
antigen
anti = antibody gen = generator
Chemicals Released by Damaged Cells: kinins
are the chemicals Vasodilation, increased permeability of blood vessels Play a role in chemotaxis by attracting phagocytic neutrophils
chemokine
chemical mediators (cytokines) that stimulate the movement of SBC
Chemotactic factors
chemical mediators that stimulate the movement of WBC(chemokines) affect white blood cells
cytokine
chemical substance produced by WBCs and tissue cells that regulate development, inflammation & immunity
Membrane attack complex (MAC)
cytolysis many different proteins. ring, hollow center, makes a hole, things leak out and cell lyses
Diapedesis
how WBCs leave the blood vessels and into tissue spaces aka extravasation
lysozyme
in tears and saliva break apart peptidoglycan cell wall
GALT
in the intestinal tract - Appendix - Peyer's patches
chemotactic
injured tissues release chemicals
margination
integrins on neutrophils help them attach to endothelial integrins receptors
endogenous
originating or produced within an organism or one of its parts (GN bacteria lipopolysaccharide layer is the causative agent)
exogenous
originating outside the body
Dolor
pain
pluripotential stem cells
primary precursor of new blood cells
hematopoesis
production of blood cells
Humoral immunity
protective molecules carried in the fluids of the body B cells
Rubor
redness
Mast cells
secrete histamine causing vasodilation, and openings occur in capillaries
Histiocytes:
specialized macrophages that migrate to a certain tissue and remain there during their life span
Tumor
swelling
Exudates
the fluid that escapes through gaps in the walls of postcapillary venules
immunology
the study of all features of the body's second and third lines of defense
chemotaxis
the tendency of WBCs to migrate in response to a specific chemical stimulus (gradient)
Calor
warmth