Part 5: Overview of Innate Immunity Flashcards Preview

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Flashcards in Part 5: Overview of Innate Immunity Deck (89):
1

Innate resistance protects against

Most infectious disease

2

Innate resistance

- Exists at birth and always present
- Natural host resistance
- Can be specific for tissues

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Parts of innate resistance

Chemical + physical barriers, special immune system cells, physiological processes and molecular defenses

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Natural host resistance

Susceptability to pathogens varies from species to species

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Example of natural host resistance

Anthrax: fatal blood infection in cattle vs. cutaneous in humans

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Infection site and tissue specificity

Pathogens prefer a specific body site to initiate infection

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Skin prevents

Invasion by microbes

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Protective protein of skin

Keratin

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pH of skin

Slightly acidic pH 5

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High [NaCl} in skin means

Periodic drying

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Mucous traps

Microbes

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Mucous contains

Antimicrobial secretions

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Example of mucous membrane secretions

Lysozyme and defensins

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Lysozyme does what?

Cuts beta-1,4 glycosidic bonds in peptidoglycan

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Defensin mechanism

Antimicrobial peptides that poke holes in bacterial cell membranes

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The mucocilliary escalator

Cilliated cells line the mucous membranes of the airways
Sweeping action moves mucous and microbes away from the lungs

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Stomach acidity

pH ~2
Proteolytic enzymes
Destroys most microbes

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Small intestine

Rapid change in pH
Pancreatic enzymes
Bile
Destroy microbes

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Large intestine: normal microbiota

Microbes that already reside and on the human body

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Large intestine: normal microbiota action

Take up attachment sites, limit available nutrients, make antimicrobial compounds

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Genitourinary tract protection

Urine, flushing action, normal microbiota

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Vaginal epithelial cells produce

Glycogen

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Lactobacillus acidophilus ferments

Glucose to lactose acid

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Lymphatic system

Collection of tissues that bring specialized cells (lymphocytes) into contact with foreign material (antigens)

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Lymphatic system is made of

Lymph vessels and lymphoid organs

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Lymph

Similar to blood containing white blood cells (leukocytes) but without red blood cells

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Primary lymphoid organs

Bone marrow and thymus

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What happens in bone marrow and thymus?

Leukocytes are produced and mature

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Secondary lymphoid organs

Lymph nodes, spleen, MALT

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Secondary lymphoid organs contain

Leukocytes arranged to filter out microbes and antigens

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Mucosa associated lymphoid tissue action

Leukocytes constantly sample their surroundings by phagocytosis looking for foreign material

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Leukocytes

Cells that circulate in the blood and lymph, and reside in lymphoid organs

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Leukocytes are involved in

Both branches of the immune response (innate and adaptive)

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Granulocytes

Cytoplasm contains granules filled with reactive chemicals that can kill microbes and signal other components of immunity

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Types of granulocytes

Basophils and mast cells
Eosinophils
Neutrophils

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Basophils and mast cells granules stain with

Basic dyes

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Basophils and mast cells are

Non-phagocytic

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Basophil and mast cell location

Circulate in blood (basophils) or reside in mucosal tissue (mast cells)

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Basophils and mast cells can be triggered to

Degranulate

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Basophils and mast cells release

Vasoactive mediators

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Vasoactive mediators

Trigger inflamation

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Type of vasoactive mediator

Histamine - involved in the allergic response

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Eosinophils granules stain with

Acidic dyes

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Eosinophils are

Non-phagocytic

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Eosinophil location

Can leave the blood and enter tissues in areas of inflammation

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Eosinophils attack

Large parasites - protozoa and parasitic worms

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Eosinophils release

Reactive oxygen intermediates that destroy parasite from the outside

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Oxygen intermediates

O2-, H2O2, OH

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Neutrophils

Granules are filled with digestive enzymes

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Digestive enzymes

Lysozyme and defensins

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Neutrophil locations

Circulate in blood and migrate to infection sites

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Neutrophils action

Highly phagocytic - "eat" invading bacteria

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Central component of innate immunity

Neutrophils

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Monocytes location

Circulate in the blood, and then migrate to tissues, and differentiate into macrophages and dendritic cells

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Monocyte mechanism

Strongly phagocytic cells involved in antigen presentation

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Macrophages location

Reside in tissues - lungs, liver, spleen, connective tissues

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Macrophages have

Specific surface molecules that recognize pathogens - toll-like receptors

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Toll-like receptors are found on

LPS, peptidoglycan, fungal cell walls that induces phagocytosis

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Dendritic cell location

Reside in tissues that serve as common entry points for pathogens: skin (langerhan's cells) and mucous membranes of the nose, lungs, and intestines

60

Dendritic cells sample their surroundings using

Phagocytosis

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Dendritic cell action

Migrate to lymphoid organs then present foreign antigens on their surface to B and T lymphocytes - trigger the specific (adaptive) immune response

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Lymphocytes are

Specialized leukocytes involved primarily in the adaptive immune response

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Lymphocyte location

Circulate through the blood and reside in lymphoid organs

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B lymphocytes

Antibody producing cells

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B lymphocytes are involved in

Humoral immune response

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T lymphocytes are involved in

Cell mediated immune response

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Natural killer cells destroy

Abnormal cells: cancer cells, cells infected by bacteria or viruses

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Innate immunity has the ability

To destroy a pathogen that has never been encountered before

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Innate immunity involves

Phagocytic leukocytes (neutrophils and macrophages)

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Phagocytic leukocytes can recognize

Pathogen-associated molecular patterns (PAMPs)

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Pathogen-associated molecular patterns are found on

Lipopolysaccharide
Lipoteichoic acid
Flagellin

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What do we find on phagocytes?

Toll-like receptors

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Toll-like receptors on phagocytes do what

Interact with a PAMP
Triggers phagocytosis

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Phagocytes engulf by

Cell membrane invaginates around a foreign particle and engulfs it into a phagosome

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Phagolysosome

A phagosome fused with a lysosome

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Phagolysosome is filled with

Lysozyme and defensins
Proteases
Lipases
Nuclease

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Proteases

Degrade proteins

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Lipases

Degrade phospholipids

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Nuclease

Degrade nucleic acids

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Oxygen dependent killing

Activated phagocytes produce reactive oxygen compounds that kill ingested microbes by oxidizing cell components

81

Oxygen compounds

H2O2, O2-, OH-, HOCl, NO

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Once invaders have been killed in oxygen dependent killing...

Neutrophils perform exocytosis - fragments are expelled from the cell
Macrophages and dendritic cells become antigen presenting cells

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Antigen presenting cells

Fragments of the intruder are presented on the cell surface to trigger an adaptive immune response

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Inflammation

General, non-specific reaction to pathogens, toxins, or tissue damage

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Five cardinal signs of inflammation

Redness, warmth, pain, swelling, and loss of function

86

In response to infection, injured tissue and leukocytes release

Proinflammatory cytokines

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Proinflammatory cytokines cause

Blood vessels to dilate - brings more leukocytes to the area

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Extravasation

Allows leukocytes to squeeze into tissues and attack invading pathogens

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Blood leaking into tissue spaces prevents

Movement of pathogens by clotting