Body Defenses
Heyer
1
Body Defenses
Pathogens & Immunity
Pathogens
•
Pathogen: an agent causing a disease
•
Microbe: microscopic organism
(most are
not
pathogens)
– Bacteria
– Protists (eukaryotic, single-celled)
– Multicellular (fungi, parasites)
•
Infectious particles (non-living)
– Viruses: nucleic acids wrapped in protein capsid
– Prions: rogue proteins
Pathogens
First line of Defense:
Barriers
•
Stratified squamous epithelia
– Skin; mucous membranes
•
Flushing action
– Urine, tears, saliva, sweat, oil glands
•
Mucus traps
– Respiratory, digestive, and vaginal tracts
•
Lysozyme (enzyme digests bacterial walls)
– Tears, sweat, saliva
•
Acidic pH
– Stomach, vaginal secretions
•
High body temperature
•
Competition from microflora (resident microbes)
Second line of Defense:
Non-specific Responses
•
Macrophages and Fixed Phagocytes
– Phagocytosis of any “non-self” cell
• Inflammation
Inflammatory Response
•
Hallmark symptoms of inflammation:
redness, heat, swelling and pain
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Body Defenses
Heyer
2
Third line of Defense:
Specific Responses (Immunity)
The Lymphatic System
•
B-lymphocytes &
antibody-mediated defense
–
Esp. vs. bacteria, chemical toxins, & free viruses
•
T-lymphocytes &
cell-mediated defense
–
Esp. vs. eukaryotic pathogens: parasites,
viral-infected cells, cancerous cells, & transplanted
tissues
The Lymphatic System
•
Lymphatic
circulation
•
Lymphoid
tissues
The Lymphatic System
•
Lymphatic
circulation
Lymphatic vessel with valve
The Lymphatic System
•
Lymphoid
tissues
The Lymphatic System
•

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- Fall '08
- Heyer
- Bacteria, Fungi, Human Biology, Heyer, Immune System Disorders
-
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