Innate Immunity Overview and Key Concepts

Innate Immunity

First line of defense against pathogens, non-specific.

Physical Defenses

Barriers preventing pathogen entry into tissues.

Chemical Defenses

Mediators inhibiting microbial growth in the body.

Cellular Defenses

Cells involved in recognizing and eliminating pathogens.

Pathogen Recognition

Identifying foreign substances by the immune system.

Phagocytosis

Process of engulfing and digesting pathogens.

Inflammation

Response to injury or infection causing swelling and redness.

Fever

Increased body temperature to enhance immune response.

Physical Barriers

Structures preventing pathogens from reaching target tissues.

Tight Junctions

Cellular connections preventing pathogen passage between cells.

Desmosomes

Cell structures providing adhesion between adjacent cells.

Gap Junctions

Channels allowing communication between adjacent cells.

Hyaluronidase

Enzyme used by pathogens to break cellular junctions.

Skin

Primary physical barrier against environmental pathogens.

Epidermis Shedding

Process of skin cell loss aiding in microbe removal.

Keratin

Protein in skin providing resistance to microbial enzymes.

Salt

Chemical that inhibits microbial growth on skin.

Mucous Membranes

Protective linings in respiratory and digestive tracts.

Goblet Cells

Intestinal cells producing mucus with antimicrobial properties.

Mucociliary Escalator

Mechanism moving mucus out of lungs via cilia.

Endothelia

Tightly packed cells lining blood and lymphatic vessels.

Blood-Brain Barrier

Endothelial barrier protecting the central nervous system.

Microbiome Defense

Beneficial microbes competing against potential pathogens.

Cytokines

Signaling proteins regulating immune responses.

Antimicrobial Peptides

Small proteins disrupting microbial cell membranes.

Plasma Protein Mediators

Proteins in blood aiding in immune response.

Sebum

Oil from sebaceous glands sealing pores.

Propionibacterium acnes

Bacteria digesting sebum, lowering skin pH.

Saliva

Fluid containing lactoperoxidase for pathogen defense.

Lactoperoxidase system

Catalyzes hydrogen peroxide activity in saliva.

Stomach acid

Digestive fluid eliminating most pathogens.

Paneth cells

Cells producing antimicrobial substances in intestines.

Lactobacilli

Bacteria fermenting glycogen to lower vaginal pH.

Tears

Fluid containing lysozyme and lactoferrin for protection.

Antimicrobial peptides (AMPs)

Cell-derived mediators with broad-spectrum antimicrobial properties.

Cytokines

Proteins stimulating immune cells for chemical defenses.

Acute phase proteins

Liver-produced proteins secreted into blood during inflammation.

C-reactive proteins

Acute phase protein indicating inflammation in blood.

Ferritin

Protein storing iron, involved in immune response.

Transferrin

Protein transporting iron in the bloodstream.

Fibrinogen

Protein involved in blood clotting and inflammation.

Complement system

Blood proteins connecting innate and adaptive immunity.

Alternative pathway

Complement activation initiated by spontaneous C3 activation.

Classical pathway

Complement activation via antibody binding to pathogens.

Lectin pathway

Complement activation triggered by mannose-binding lectin.

Opsonization

Coating pathogens for easier phagocytosis.

Membrane attack complex (MAC)

Complex forming pores in Gram-negative bacteria.

Interleukins

Cytokines recruiting immune cells to infection sites.

Chemokines

Cytokines recruiting specific leukocytes to inflammation.

Interferons

Proteins released during viral infections to recruit immune cells.

Cytokines

Signaling proteins that induce inflammatory mediator production.

Histamine

Chemical causing bronchoconstriction during inflammation.

Leukotrienes

Mediators inducing coughing, vomiting, and diarrhea.

Prostaglandins

Compounds that induce fever during inflammatory responses.

Bradykinin

Peptide increasing capillary permeability, contributing to edema.

Hematopoiesis

Process of blood cell differentiation from stem cells.

Granulocytes

Type of white blood cells involved in innate immunity.

Neutrophils

White blood cells that destroy extracellular bacteria.

Eosinophils

White blood cells with 2-3 lobes, combating parasites.

Basophils

White blood cells with large granules, involved in allergies.

Natural Killer Cells

Agranulocytes targeting virus-infected and tumor cells.

Neutrophil Extracellular Traps (NETs)

Mesh of chromatin trapping pathogens during immune response.

Pus Formation

Accumulation of leukocytes, debris, and bacteria at infection site.

Eosinophils

Protect against protozoa and helminths.

Basophils

Involved in allergic reactions and inflammation.

Mast Cells

Reside near blood vessels and nerves.

Agranulocytes

Lack visible granules in cytoplasm.

Natural Killer Cells

Target tumors and virus-infected cells.

Monocytes

Largest type of white blood cells.

Phagocytosis

Process of engulfing pathogens by cells.

Diapedesis

Leukocytes passing through capillary walls.

Transendothelial Migration

Leukocytes flatten and squeeze through junctions.

Pathogen-Associated Molecular Patterns (PAMPs)

Molecules recognized by phagocytes for pathogen detection.

Pattern Recognition Receptors (PRRs)

Detect PAMPs on phagocytic cells.

Toll-Like Receptors (TLRs)

Bind PAMPs to activate phagocyte response.

Phagosome

Vesicle formed around engulfed pathogen.

Phagolysosome

Fusion of phagosome and lysosome for degradation.

Inflammation

Response to recruit immune cells and repair.

Acute Inflammation

Immediate response causing redness, swelling, heat.

Chronic Inflammation

Prolonged response with potential granuloma formation.

Fever

Systemic response raising body temperature.

Pyrogens

Substances that induce fever by altering hypothalamus.

Exogenous Pyrogens

Produced by pathogens, like LPS.

Endogenous Pyrogens

Produced by leukocytes, such as interleukins.

Cytokines

Signaling proteins involved in immune responses.

Granules

Contain histamine and enzymes in immune cells.