Host Defenses Flashcards
Cells of the immune system
- Monocytes
- Granulocytes
- Lymphocytes
Monocytes
- Circulate In blood stream
- Attracted to inflamed tissues
- Phagocytic
- Differentiate into macrophages & dendritic cells
Granulocytes
- Cytoplams contains granules
Includes:
* eosinophils
* basophils
* neutrophils (phagocytic)
* mast cells (induce inflammation)
Lmphocytes
- T cells: helper, cytotoxic
- B cells: antibodies
Innate defenses
- Properties of the normal host
- Non specific
Innate defenses of skin and mucous membrane
Skin:
* Thick layer of dead cells
Normal microbiome
* competes for attachment sites and nutrients
* secretes bacteriocin
Antimicrobial substances
* fatty acids
* Lysosymes
* antimicrobial peptides (AMPs)
* Antibodies
Mucous membrane
* Secretes mucous that traps bacteria
Innate defenses of the airways
- Mucous membrane that traps bacteria
- Ciliated cells remove mucus and trapped bacteria
Innate defenses of tissues and internal fluids
- Complement system
- Phagocytosis
- Inflammation
Complement system
- Set of blood proteins
- Activation results in the formation membrane attach complex (MAC)
- Causes cell lysis of some Gram-negatives
- No effect on Gram positives
Complement system activation pathways
- Classical: Antibodies
- Alternative: Microbial cell wall components
Serum sensitivity
Test sensitivity to complement by exposing pathogens to serum
Phagocytosis: Steps
- Attachement of organism to the membrane of the phagocyte
- Ingestion (organism becomes enclosed in a phagosome
- Granules containing hydrolytic enwymes fuse zith the phagosome forming the phagolysosome
- Oxidative burst (production of ROS)
- Killing and digestion of the microorganism
Phagocytes
- Neutrophils
- Macrophages
Inflammation: Signs
- Redness
- Heat
- Swelling
- Pain