Host Defense Mechanisms, pg. 72/73

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Surface barriers, inflammation, and immune response
What are the 3 host defense mechanisms?
Surface barriers
What is the first line of defense?
The first line of defense includes...
Epidermis and mucosa, secretions (mucus, saliva, lacrimal, etc.), and normal microbiota on the skin and mucosa
The epidermis and mucosa are...
A good barrier when intact and have ciliated cells (lower respiratory)
Normal microbiota on skin and mucosa...
Colonize niches; out-compete pathogens, disease may result if killed (antibiotics, etc.)
Inflammation
What is the second line of defense?
The second line of defense includes...
Inflammatory mediators (bradykinin, histamine, etc.) and complement
Inflammatory mediators...
Alter blood flow, capillary permeability, etc., and attract phagocytic WBC's by chemotaxis
PMN's (neutrophils) come...
First, eat MO's, and release enzymes
Macrophages come...
Later, efficient killers and eaters, release toxic forms of oxygen (NO, nitric oxide), produce interleukins (IL); enhance response
Complement
Serum proteins that can become activated; help immune system destroy invaders
The Immune Response
What is the third line of defense?
Antigens (from MO) stimulate...
lymphocytes (B cells and T cells
B Cells
Produce plasma cells and make antibodies
Antibodies
Proteins that bind to antigens
IgC
Circulates in blood; Attaches to bacteria, viruses and Inactivates toxins
IgA
In secretions
IgM
Clumps antigens together
T Cells
Cell-mediated response (cell-to-cell contact), Kills MO's and regulate immune response, Remove abnormal or virus-infected cells
Immunization (Vaccination)
Antigens are injected; MO's (weakened or dead), components, neutralize toxins; Stimulates immune response (B cells, T cells, and memory cells)
Memory Cells
Confer immunity (future)
DPT (Diptheria, Pertussis, Tetanus)
Contains cells fragments from Bordetella pertussisi and toxoids made from Diptheria and Tetanus exotoxins
Toxoids
Inactivated by heat, formaldehyde, etc.; Still antigenic: body produces antitoxins (antibodies) against them