CLINICAL DOCUMENTATION, Cheat Sheet of Clinical Medicine

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BIO 255 WK 5

PRACTICE Q’S FOR WK

5 IMMUNITY LECTURE

Immune System

Adaptive Immunity

Adaptive immunity is the body’s ability

to defend against specific antigens

(substances that are recognized as

foreign and provoke an immune

response)

Two types of Adaptive Immunity

Cell-mediated

Antibody-mediated

Adaptive Immunity

Cell mediated:

Defense against infected cell

Antigen has invaded cells

Infected cells are destroyed by

Cytotoxic T cells

Antibody mediated (humoral immunity):

Defense against antigens in body

fluids

Antigen is outside of cells

Antigens are destroyed by antibodies

that are made by Plasma cells (B cells)

Innate Immunity: First & Second Lines of Defense

First Line of Defense: External Barriers

• (^) Skin : tough outer barrier due to keratin in skin
• (^) Sloughing of outer layer of skin prevents attachment
• (^) Dry, salty, acidic environment inhibits microbial growth - (^) Antimicrobial peptides secreted in sebum and sweat
• (^) Mucous membranes : protect digestive, respiratory, urinary, and reproductive tracts as they are open to the exterior - (^) Mucus physically traps microbes
• (^) cilia propels mucus out of lower respiratory tract to be expectorated or swallowed and destroyed by stomach acid
• (^) Microorganisms in upper digestive tract are destroyed by stomach acid and flashed from lower urinary tract

Second Line of Defense: Antimicrobial Proteins

• (^) Antimicrobial proteins : blood- borne proteins that inhibit microbial reproduction and provide short-term, innate immunity - (^) Interferons (IFNs) : released by virally-infected cells to warn neighbors of potential for infection and prevent spread - (^) No benefit to the cell that secretes them - (^) Warned neighboring cells can defend against virus and inhibit virus replication - (^) Activates NK cells and macrophages to kill

Second Line of Defense: Complement Proteins

Complement Proteins : group of inactive proteins in blood plasma

• (^) Undergo chemical chain reaction when activated by pathogen
• (^) Each activated protein activates the next in the series Activated by:
• (^) Antibodies from immune system that are bound to pathogen, this marks the pathogen for destruction- OPSONIZATION (classical pathway).
• (^) Bacterial carbohydrates of antigens that set off cascade of complete proteins (lectin pathway)
• (^) Spontaneous binding of protein to pathogen (alternative pathway) Results in: inflammation, phagocytosis, cytolysis

Second Line of Defense: Protective Cells

• (^) Neutrophils : phagocytic cells that engulf and destroy pathogens - (^) First to arrive as a response to injury or infection - (^) Can also kill surrounding bacterial cells through a respiratory burst (cell releases toxic chemicals, killing everything around it) Eosinophils : guard against parasitic worm infections
  • (^) Release toxic chemicals to kill parasite
  • (^) Also cause allergies (along with basophils and mast cells) Basophils : work with eosinophils and mast cells
  • (^) Secrete chemicals (leukotrienes, heparin, and histamine) to promote inflammation and activate other leukocytes

Second Line of Defense: Protective Cells

• (^) Monocytes (macrophages in tissues): phagocytes and APCs
  • (^) Phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter
  • (^) Also includes dendritic cells and reticular cells
  • (^) Most patrol body for infections, some fixed in place (i.e., microglia in nervous system, alveolar macrophages in lungs, stellate macrophages in liver)

Second Line of Defense: Protective Processes

• (^) Inflammation : local, innate response to infection or tissue injury
• (^) Limits spread of pathogens, then destroys them
  • (^) Removes debris from damaged tissue
  • (^) Initiates tissue repair
• (^) Four cardinal signs of inflammation:
  • (^) Heat (calor)
  • (^) Redness (rubor)
  • (^) Swelling (tumor)
  • (^) Pain (dolor) Due to increased blood flow to area (brings more WBCs to area) Due to fluid accumulation from increased leakiness of blood capillaries in area (allows more WBCs to leave bloodstream)

• (^) Inflammation causes hyperemia , or an increased blood flow to a given area
• (^) This occurs because of:
  • (^) Vasodilation caused by chemicals (histamine, leukotrienes) released by basophils and mast cells or damaged cells - (^) Allows WBCs to get to area quickly
  • (^) Increased capillary permeability that creates large gaps between endothelial cells for WBCs to fit through Second Line of Defense: Protective Processes

Adaptive Immunity

• (^) Third line of defense:
  • (^) Systemic effect: throughout the body
  • (^) Specificity: immunity directed against one specific pathogen
  • (^) Memory: immune system will remember pathogen and react more quickly when re-exposed Two types of adaptive immunity:
  • (^) Cellular (cell-mediated) immunity : T cells directly attack and destroy foreign cells or diseased host cells
• (^) Targets intracellular pathogens inaccessible to antibodies (virus- infected cells, abnormal cells, cancer cells, foreign transplanted tissues)
  • (^) Humoral (antibody-mediated) immunity : B cells employ antibodies that tag pathogens for destruction
• (^) Targets extracellular pathogens (viruses when not inside host cells, bacteria, yeasts, protozoans, etc.)

Forms of Adaptive Immunity: Active Immunity

• (^) Active immunity: body’s own immune system reacts to antigen; produces long- lasting memory cells
• (^) Natural active immunity : body is naturally exposed to antigen and produces antibodies (normal infection)
• (^) Artificial active immunity : body is exposed artificially to antigen to generate immune response - (^) Vaccine : consists of dead or attenuated (weakened) pathogens that stimulate the immune response without causing the disease - (^) Booster shots: periodic immunizations to stimulate immune memory to maintain a high level of protection