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Lecture 19

BIOL 1353 Lecture Notes - Lecture 19: Innate Immune System, Mucous Membrane, Dendritic Cell

Course Code
BIOL 1353

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Chapter 16 Innate Immunity
- Innate Immunity: inborn; always present; nonspecific
o First line of defense
Intact skin
Mucous membranes and their secretions
Normal microbiota outside stuff has to compete with the bacteria that’s
already there
o Second line of defense
Phagocytes, such as neutrophils, eosinophils, dendritic cells, and
Antimicrobial substances
Typically triggered by events that occurred in first line. All lines are
triggered by the release of chemicals
Complement (soluble protein factors in the blood that can become active
and generate diff defenses)
- Adaptive immunity (third line of defense) (Specific defense)
o Specialized lymphocytes: T cells and B cells
o Antibodies
o Stimulated by the presence of oxygen why it’s called “specific”
o Innate immunity works faster than adaptive immunity

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o Adaptive memory has a memory to it; it can remember prior
infections/exposures. Next time you get introduced to that specific virus your
adaptive immunity works faster
- Immunity
o Activated by toll-like receptors (TLR) on host cells recognize pathogen
associated molecular patterns (PAMPS) (structures on the periphery of the
PAMPS: LPS of gram negatives, peptidoglycan, flagella, viral RNA/DNA
Viral RNA and DNA can trigger internal receptors
Induces release of cytokines: regulate immune response
Cytokines is a generic term that describes a number of diff chemicals
invovled in this innate and immune response. It gives instructions to
certain cells
o activate macrophages (making it a better phagocytic cell
o **phagocytosis: cell engulfs another cell
o chemotactic effects bringing the cells of immune system to
the site where the infection is occuring
o inflammatory response/fever
o activate T and B cells
First line of defense
- Physical factors
o Skin: comprised of epidermis and dermis; protective keratin layer on epidermis
Subcutaneous infection: when skin penetrated
o Mucous membranes: line GI, GU, & respiratory tracts; epithelial & connective
tissue layers
Mucus: traps microbes, moistens surfaces
Tears and saliva: prevent colonization of microbes
Hair (nose) and cilia (respiratory tract): trap microbes
Mucociliary escalator (produce mucous, and mucous can have
track microbes and cilia that helps it move up your respiratory
tract and you cough it up)
Epiglottis, earwax, digestion: eliminates microbes earwax Is acidic?
- Chemical factors
o Skin: sebum (oily secretions) forms a film on skin
Contains fatty acids, low pH prevent colonization of pathogens
Perspiration: high salt; contain lysozyme (degrades peptidoglycan) (also
in tears, saliva, etc.)
Remember peptidoglycan makes up the cell wall of bacteria
o Mucous membranes:
Saliva: lysozyme, urea, uric acid, antibody
Gastric juice (stomach): pH 1-3 due to HCl
Vaginal secretions: acidic pH
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