C2 - LESSON 1: NATURAL IMMUNITY Flashcards
Ability of the individual to resist infection by means of normally present body functions
NATURAL IMMUNITY
Factors involved in natural immunity:
- Physical barriers, such as skin and mucous membranes
- Genetically controlled susceptibility and non-susceptibility to certain diseases
- Inflammation- involves a vascular response and a cellular response by phagocytic cells
- Acute-phase plasma proteins, such as C-reactive protein, haptoglobin, and fibrinogen, which are produced in response to injury and aid in wound healing
Factors Influencing Innate Immunity:
a. Age
b. Nutritional Status
c. Hormonal Levels
Mechanisms of Innate Immunity
a. Anatomic Barriers
b. Physiologic Barriers
c. Phagocytosis
d. Inflammatory Responses
- first barrier to infection.
• Unbroken Skin and mucosal membrane surfaces
Keratinization
- microorganisms normally inhabiting the skin and membranes
• Normal flora
provides additional protection to the respiratory tract.
• Constant motion of the cilia of the tubules
• Secretions - mucus adhering to the membranes of the nose and nasopharynx traps microorganisms, which can be expelled by
coughing or sneezing.
- produced by the sebaceous glands of the skin and lactic acid in sweat both possess antimicrobial properties.
Sebum (oil)
- protects the auditory canals from infectious disease
Earwax (cerumen)
Secretions produced in the elimination of
liquid and solid waste
Acidity and alkalinity of the
stomach and intestinal tract
Acidity of the
vagina
- characterized as a nonspecific mechanism.
Natural immunity (inborn or innate resistance)
If a microorganism penetrates the skin or mucosal membranes, a (?) becomes operational.
second line of cellular and humoral defense mechanisms
The elements of natural resistance include:
▪ phagocytic cells
▪ complement
▪ acute inflammatory reaction
Cellular Factors
- Phagocytes
- Basophils and Mast Cells
- Natural Killer Cells
- Antigen Presenting Cells
Humoral Factors
- Complement System
- Cytokines
- Interferons
- Inflammatory Substances
Phagocytic Cells
polymorphonuclear neutrophilic (PMN) leukocyte
Neutrophils
50-70% of total population
Neutrophils
10-15 um in diameter
Neutrophils
Contain neutral staining granules
Neutrophils
Neutrophil granules
➢ Primary (Azurophilic granules)
➢ Secondary (Collagenase and lysozymes
12-15 um in diameter
Eosinophil
1-3% of circulating WBC (Non-allergic individual)
Eosinophil
In staining-takes up the acid eosin dye
Eosinophil
Found in very small numbers
Basophils
10-15 um in diameter
Basophils
Contains course densely staining deep-bluish granules
Basophils
Basophil Granules:
histamine, small amount of heparin and Chemotactic factor –A
Resembles basophils
Mast Cells
Widely distributed through-out the body
Mast Cells
Mast Cell Granules:
acid phosphatase, alkaline phosphatase and protease
Important in hypersensitivity reaction
Mast Cells
12-22 umm in diameter
Monocytes/Mononuclear cells
Horse shoe shape nucleus
Monocytes/Mononuclear cells
Dust like granules
Monocytes/Mononuclear cells
4-10% of total circulating WBC
Monocytes/Mononuclear cells
Stay in the peripheral blood for up to 70 hours then migrate to tissues to become macrophages
Monocytes/Mononuclear cells
Contains peroxidase enzyme
Monocytes/Mononuclear cells
All arise from monocytes
Tissue Macrophages
25-80 um
Tissue Macrophages
No peroxidase enzyme
Tissue Macrophages
Names are specific for tissue location
Tissue Macrophages
Tissue Macrophages Functions:
Microbial killing, tumoricidal activity, intracellular parasite eradication, phagocytosis and antigen presentation
Covered with long membranous extensions
Dendritic Cells
Dendritic Cells Main function:
Phagocytosis and presentation of antigens to helper T lymphocytes
Classified according to tissue location
Dendritic Cells
TOLL-LIKE RECEPTORS
Originally discovered in the fruit fly Drosophila
TOLL-LIKE RECEPTORS