Inflammation and Immune System

Properly know the pathways and cells responsible for inflammation, and how our body’s immunity works

Innate Immunity

-first line of defense -fast acting -includes physical, mechanical, and biochemical mechanisms

Innate Immunity:Physical Barriers

-epithelial cells -low temps -low pH of skin and stomach

Innate Immunity: Mechanical Barriers

-any clearing of pathogen -vomiting -urination -goblets cells of Upper respiratory tract

Innate Immunity: Biochemical Barriers

chemicals secreted by epithelial or glands that trap, or destroy pathogens

Antimicrobial fatty acids and lactic acid

-Secreted by sebaceous glands of the skin -Antimicrobials stop pathogen growth on the skin

Antimicrobial peptides

-secreted by epithelial -direct destroy of pathogens

Lysozyme

-sweat, tears, saliva -chemical protection

Antimicrobial acids are secreted by ___ and Antimicrobial peptides are secreted by ___

sebaceous glands, epithelial cells

Innate immunity: Normal microbiome

usually non-pathogenic bacteria and fungi -competes with pathogens for space and secretes chemicals → inhibits growth -adult flora →suppresses growth

Innate Immunity: Failure due to Medications

Certain antibiotics(e.g immunosuppressants med) can disrupt adult flora→ opportunistic infections

Examples of opportunistic infections

-candida albicans (thrush) -C diff(pseudomembranous colitis)

Innate Immunity: GU Tract

-flushes bacteria and disrupts adhesion -increased risk of if reflux, obstruction or short urethra

Innate Immunity: Respiratory Tract

-mucociliary blanket -goblet cells -cilia -alveolar macrophages

Mucociliary Blanket

-nose and respiratory tract lining -smoking damages this

Goblet cells

-secretes mucous and traps microbes

Cilia

-moves bacteria to either be swallowed or expelled

Alveolar macrophages

-destroys small bacteria in the airways

Innate immunity: GI Tract Examples

-gastric acid -viscous mucous -pancreatic enzymes/bile detergents -IgA(in gut, removes microorganisms) -bacterial flora

Innate immunity: GI Tract Protection Against

pathogens transported via food contaminated with fecal material

Inflammation

-second line of defense -responds to tissue injury

Cells of Inflammation

-endothelial cells -mast cells -dendritic cells -eosinophils -monocytes/macrophages

Endothelial Cells

-lining of blood vessels -release nitric oxide → vasodilation -release inflammatory mediators -regulate movement of cells

Plasma-derived mediators

-synthesized in liver -coagulation and complement protein factors

Cell-derived mediators

-located in intracellular granules, secreted in response to stimulus -EXAMPLE: histamine from mast cells

Production pathway of mediators

Entry of microbes or damaged tissues → actives coagulation systems → produces active mediators

Cells of Inflammation: Mast cells

-release inflammatory mediators such as histamine -synthesize new inflammatory mediators

Neutrophils

-first to arrive in inflammation -don’t survive for long -become part of purulent exudate (pus)

Eosinophils

“Worms, wheezes, and weird diseases”

Dendritic Cells

-APC’s (antigen presenting cells) -initiates adaptive immunity

Monocytes/Macrophages

Monocytes → precursor for macrophages -last longer and in acidic environments -cleans pathogens and debris from damaged tissue -initiates adaptive immunity

Arachidonic Acid Metabolites (from textbook)

-fatty acid found in the phospholipids of cell membranes -produces inflammatory mediators from eicosanoid such as prostaglandins, LT, etc

What are the arachnoid acid metabolite pathways?

-cyclooxygenase and lipoxygenase

Cyclooxygenase

-produces prostaglandins and thromboxane -both promote platelet aggregation and vasoconstriction

Lipoxygenase

Produces leukotrienes → smooth muscle contraction, airway constriction, microvascular permeability -TAKES OVER FOR HISTAMINE

Chemical mediator: Histamine

-first mediator released -produced by mast cells -vasodilation, increase permeability, bronchoconstriction

Chemical mediator: Bradykinin