1. Human Anatomy and Physiology
Immunology: Innate defenses

2. Overview
Not organ associated but comprised of cells inhabiting lymph and body fluids
Innate system
Surface membranes: skin and mucosae
Internal defenses: phagocytes, fever, NK cells, antimicrobial proteins, inflammation
Adaptive system
Humoral immunity (B cell)
Cellular immunity (T cell)

3. Surface barriers Integument (skin) Epithelial membranes
Multilayered skin
Keratin stops bacterial enzymes and toxins
Epithelial membranes
Acidic skin secretions
Acid stomach mucosa
Saliva contains lysozyme
Respiratory and digestive tract mucus

4. Internal barriers Phagocytes Macrophages “big-eaters”
E.g. monocytes, neutrophils
Phagocytosis - steps
Engulf (1,2)
Formation of vesicle (3)
Lysozome fusion (4)
Digestion
Exocytosis (5)

5. Internal barriers Natural killer cells
Non-specific killers (e.g. viruses, cancer cells)
Recognize sugars on surface of target cell
Attacks target cell’s membrane releasing perforins
nuclear disintegration and inflammation

6. Internal barriers Inflammation Signs Inflammatory process
Redness, heat, swelling, pain, impairment of function
Inflammatory process
Receptors on cell surface release chemicals (histamine, kinins, etc.)
Cause small blood vessels to dilate = redness and heat
Chemicals increase capillary permeability, fluid causes edema, edema causes pain

7. Inflammation Aids healing process Dilution of harmful substances
Oxygen and nutrients
Clotting proteins

8. Inflammation Phagocyte mobilization follows inflammation Process
Leukocytosis (1)
Margination (2)
Diapedesis (3)
Chemotaxis (4)

9. Internal barriers Viruses cannot replicate themselves How viruses work
Antimicrobial proteins - interferon

10. Interferons Steps Virus enters host and replicates
Infected cells secrete interferons
Interferons stimulate production of antiviral proteins
Antiviral proteins prevent virus replication

11. Internal barriers Fever
Liver and spleen sequester iron and zinc during fever
Speeds up metabolism