Ch.16 Innate Immunity: Nonspecific Defenses of the Host

Describe the role of iron-binding proteins in innate immunity

-Most iron in the body is bound to iron-binding proteins, depriving most pathogens of available iron

Describe the role of antimicrobial peptides in innate immunity

-Short peptides (12-50 aa) produced in response to protein and sugar molecules on microbes *Produced by nearly all plants and animals -Broad spectrum of activity against bacteria, viruses, fungi, and eukaryotic parasites *Inhibit cell wall synthesis *Form pores in the plasma membrane *Destroy DNA and RNA

Describe the process of phagocytosis

1.) CHEMOTAXIS -chemical signals attract phagocytes to microorganisms 2.) ADHERENCE -attachment of a phagocyte to the surface -Toll-like receptors (TLR)s on phagocytes attach to various components commonly found on micorbes called pathogenassociated molecular patterns (PAMPs) -Microbe may be coated with serum proteins (opsonization), making adherence easier 3.) INGESTION -Pseudopods engulf the microbe and enclose it in a phagosome (phagocytic vesicle) 4.) DIGESTION -Phagosome fusses with lysosomes to form a phagolysosome -Microbe is digested by lososmal enzymes and oxidizing agents -Indigestible material is left in the residual body -Residual body discharges its wastes outside the cell

Describe three consequences of complement activation

1.) CYTOLYSIS -Activated complement proteins form a membrane attack complex (MAC), creating holes in the microbe's cell membrane -Fluid flows into the cell, resulting in the cell bursting 2.) OPSONIZATION -Microbe is coated with activated complement proteins -Promotes attachment of a phagocyte to a microbe 3.) INFLAMMATION -Activated complement proteins bind to mast cells, releasing histamine and other chemicals that increase blood vessel permeability -chemotactic factor that attracts phagocytes

Describe the actions of alpha, beta, and gamma interferons (Interferons (IFNs are a family of cytokines produced by certain cells)

ALPHA IFN (IFN-a) & BETA IFN (IFN-B) -are produced by cells in response to viral infections; cause neighboring uninfected cells to produce antiviral proteins (AVPs) that inhibit viral replication GAMMA IFN (IFN-y) -activates neutrophils and macrophages to kill bacteria

Describe the cause and effects of fever

CAUSE: -Cytokines cause the hypothalamus to release prostaglandins that reset the hypothalamus to a higher temperature EFFECT: -High body temperature intensifies the effects of antiviral interferons, inhibits growth of some microbes, speeds up body reactions that aid tissue repair

What is the complement system?

COMPLEMENT SYSTEM -Serum proteins produced by the liver that assist the immune system in destroying microbes *Complement proteins are inactive until split into fragments, which activates them *Act in a cascade (one reaction triggers another) in a process called complement activation

What are the functions of inflammation?

FUNCTIONS OF INFLAMMATION -Destroy and remove injurious agent -Limit its effects on the body by walling off agent -Repair or replace damaged tissue

Which cell types are involved in either innate immunity, adaptive immunity, or both?

INNATE IMMUNITY -Basophil -Eosinophil -Mast cell ADAPTIVE IMMUNITY -Plasma Cell, B cell -T Cells BOTH -Neutrophil -Monocyte -Dendritic Cell -Natural Killer (NK) cell

Differentiate innate and adaptive immunity

INNATE IMMUNITY -first and second-line defenses -Defenses against any pathogen (no specific) -Defenses are present at birth -Rapid response -Does not have a memory component ADAPTIVE IMMUNITY -third-line defenses -Immunity or resistance to a specific pathogen -Slower to respond -Has a memory component *Effectiveness increases on repeated exposure to agent (more rapid and stronger response)

Name examples of physical and chemical factors involved in innate immunity

PHYSICAL -skin -mucous membranes -lacrimal apparatus -ciliary escalator -saliva -earwax -urine CHEMICAL -sebum -lysozyme -gastric juice

What are the signs and symptoms of inflammation? (Inflammation is damage to the body's tissues triggers a local defensive response)

SIGNS AND SYMPTOMS -redness -pain -heat -swelling (edema)

Describe the 3 stages of inflammation

THREE INFLAMMATION STAGES: 1.) Vasodilation and increased permeability -Damaged cells release chemicals that cause vasodilation (increased diameter of blood vessels) and increased permeability of blood vessels -Blood clots form to prevent the microbe rom spreading 2.) Phagocyte migration and phagocytosis -Margination is the sticking of phagocytes to the endothelium of blood vessels in response to cytokines at the site of inflammation -Phagocytes squeeze between endothelial cells of blood vessels via diapedesis -Phagocytes then destroy microbes by phagocytosis -Pus forms as damaged tissue and dead microbes and phagocytes accumulate 3.) Tissue Repair -Cannot be completed until all harmful substances are removed or neutralized -Tissue is repaired when the stroma (supporting connective tissue) or parenchyma (functioning part of the tissue) produces new cells -Ability to regenerate depends on the type of tissue

Describe three pathways of activating complement

THREE PATHWAYS OF ACTIVATING COMPLEMENT: 1.) The Classical Pathway -Initiated when antibodies bind to antigens 2.) Alternative Pathway -Does not involve antibodies -Initiated by contact between complement proteins (factor B, factor D, factor P) and pathogen 3.) Lectin Pathway -Macrophages ingest pathogens, releasing cytokines that stimulate lectin production in the liver -Mannose-binding lectin (MBL) recognizes distinctive patterns of carbohydrates containing mannose, which is found in bacterial cell walls and on some viruses

Which types of cells are phagocytes?

TYPES OF CELL PHAGOCYTES -monocytes --> macrophages -dendritic cells -neutrophils -eosinophils