Lecture 41: Innate Immunity 1 Flashcards
Physical Barrier:
- The Skin
- Epidermis: Dead cells, keratin, and phagocytic immune cells
- Dendritic cell (innate immune cell)
Chemical defences of the skin:
- Antimicrobial peptides eg. skin ‘defensins’
- Often work by forming pore in microbial membranes
- Broad acting
- Lysozyme: enzyme that breaks down bacteria cell walls, found in tears, saliva, and urine as well
- Sebaceous gland under skin near hair follicle, acidic pH, prevents microbes from colonising and growing on skin
- Salt: (sweat) creates hypertonic environment - dehydrates pathogens
Mucous Membranes - Physical and Chemical Barriers:
- Traps microbes trying to invade body
- 1 - 2 layer of epithelial cells that are tightly packed together (hard for microbes to get in), constantly renewed, mucus-producing goblet cells
- Wineglass looking cells (goblet cells), constantly bathed in mucosal fluid
Where are mucosal membranes?
- Ocular
- Oral
- Respiratory
- Urogenital/Rectal
The Mucociliary escalator:
- Hair-like projections (cilia)
- Beat in tandem and push mucus up (inhaled particles) by sneezing, coughing, sometimes swallowing
- Smoking = paralyzed cilia
- People who smoke = more susceptible to respiratory infection
Gastrointestinal Tract:
- Stomach - low pH
- Gall bladder - bile
- Intestine - digestive enzymes (help break down microbes)
- Mucus - helps flush out and trap organisms
Tears for defence of the eyes:
- Flushing action
- Lysozymes
- Drainage, swallowed
Urogenital tract:
- Urine flow
- Lysozyme
- Low pH (not as much as stomach but still low, to discourage microbe growth)
- High osmolarity
Interference with a pathogen provokes:
- Anti microbial peptide production
- Interferon production
- Activation of the complement system
Antimicrobial peptides are produced by _____ cells lining the muscosal surfaces and keratinocytes in the skin. They also _____ microbes by interfering with growth and reproduction.
- Epithelial
- Attack
Type I Interferon:
- Produced by many host cell types to combat viruses
- Signals neighbouring cells to destroy RNA and reduce protein synthesis
- Signals neighbouring infected cells to undergo apoptosis
- Activates immune cells
Cells of the Innate Sytem:
- Blood
Plasma + Cells (Leukocytes = WBC little microscopic warriors, Platelets, Erythrocytes) - Bone Marrow
Stem Cell Production
Three Blood Cell Lineages:
Erythroid –> RBCs
Myeloid –> dendritic cells, platelets
Lymphoid –> B and T lymphocytes (adaptive immune cells) - Granulocytes : neutrophils, eosinophils, basophils, mast cells
Neutrophils are highly ______. Most ______ granulocyte. _____ half life (__ - __ days). “Eat and ____”. Numbers in blood ______ during bacterial infection.
- Phagocytic
- Abundant
- Short
- 1 - 2
- Kill
- Increase
Eaosinophils, _____ numbers in blood. Some _______. Release toxic granules to ___ and ____ ____ pathogens. Mediate _____ reactions. Abnormally high eosinophil numbers in blood can indicate ______ infection.
- Low
- Phagocytosis
- Kill and break down
- Allergic
- Parasitic
Basophils DON’T ______. Release granules that can mediate _____ reactions or fight worm infection.
- Phagocytose
- Allergic
