OVERVIEW OF INNATE AND ADAPTIVE IMMUNITY IN HUMAN

When pathogens manage to cross these barriers, the internal defense mechanisms, or the second line of defense, come into action. These include phagocytic cells like macrophages and neutrophils that engulf and destroy invading microbes. The inflammatory response increases blood flow to infected tissues, bringing immune cells to the site of infection. Fever raises body temperature to inhibit microbial growth and enhance immune function. Other important components include natural killer (NK) cells, which destroy virus-infected and abnormal cells, and antimicrobial proteins such as interferons and complement proteins that help eliminate pathogens. Together, these defense systems form an effective network that protects the body from infections.

1. Innate Immunity in Vertebrates External and Internal Defense Names of Presenters: Prepared by: Syeda Zohra Fatima Reviewed by: Laiba Ejaz

2. What is Innate Immunity? First line of defense against pathogens. Present in all vertebrates. Acts immediately upon infection. Recognizes common pathogen features using PRRs (Pattern Recognition Receptors). 2

3. External Innate Immunity: Natural Barrier to pathogen in tissue. 3 Skin , body secretions and mucous membrane prevent the penetration Of pathogens into host tissues. Enzymes in saliva and acidic pH in stomach destroy microbes Prevents pathogens from reaching internal tissues

4. Internal Innate Immunity : Offers Many forms of Protection After Pathogens Enter the Body. 4 Activated when pathogens bypass external barriers Includes inflammation, phagocytosis, and immune cell activation Rapid and non-specific response

5. Inflammation and Phagocytosis: 5 Inflammation : localized response to infection Phagocytosis : immune cells engulf and destroy pathogens Key cells : neutrophils, macrophages, dendritic cells These cells recognize pathogens using PRRs

6. Pattern Recognition and PAMPs: 6 PRRs detect PAMPs (Pathogen-Associated Molecular Patterns) PAMPs are common features found on pathogens Recognition triggers immune responses like cytokine release

7. Summary: 7 External immunity : Blocks pathogens entry. Internal immunity : Eliminates pathogens inside the body. Innate immunity is fast and broad-spectrum. Essential for activating adaptive immunity.

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