1. Nonspecific Host Defenses
Introduction
Skin & Mucous Membranes
Phagocytosis
Inflammation
Fever
Antimicrobial Substances

2. Defenses - Introduction
Ability to ward off disease is resistance
Lack of resistance is susceptibility
Resistance is of two types
Nonspecific – body defenses that ward off disease without respect to organism
Specific – attack a specific type of organism; usually associated with immune system

3. Defenses – Skin & Mucus Physical Factors
Intact skin & keritin resist microbes
Lacrimal apparatus (tears & blinking protect eyes
Saliva washes teeth & gums
Mucus traps microorganisms & ciliary escalator moves mucus up & out
Urine and vaginal secretions keep organisms out of genitourinary tract

4. Defenses – Skin & Mucus Chemical Factors
Sebum – unsaturated fats which inhibit microogansisms on skin (some bacteria can metabolize – acne)
Perspiration –washes bacteria – high salt
Lysozyme digest cell wall; found in saliva, nasal secretions, tears and perspiration
Acid (pH 1-3) prevents bacterial growth in stomach
Normal bacteria inhibit pathogens

5. Defenses - Phagocytocis
Ingestion of microorganisms or particles by a cell - phagocytosis
Usually accomplished by white blood cells

6. Defenses - Phagocytocis
Blood composition
Fluid (plasma) – water, ions, proteins
Formed elements (cells)
Erythrocytes (red blood cells)
Platlets
Leukocytes (white blood cells)
Granulocytes (neutrophils, basophils, eosinophils)
Lymphocytes
Monocytes

7. Defenses - Phagocytocis
Actions of Phagocytic cells
Neutrophils & Monocytes
Monocytes are “fixed” or “wandering”
Fixed phagocytes are located in selected tissue, i.e. spleen
Granulocytes predominate in early infection; monocytes are present later in infection
Phagocytes are activated by bacterial components (lipid A) or cytokines (chemical messengers)

8. Defenses - Phagocytosis
Granulocytes

9. Defenses - Inflammation
Inflammation is a bodily response to cell damage
Characterized by
Redness (rubor)
Pain (dolar)
Heat (calor)
Swelling (tumor)
Loss of function (functio laesa)

10. Defenses - Inflammation

11. Defenses - Inflammation
Inflammatory Response Release of chemical signals
Histamine
Kinins
Prostaglandins
A biogenic amine.
Regulates physiological function in the gut.
Acts as a neurotransmitter.
Invovled in chemotaxis of white blood cells.
Derived from histidine.

12. Defenses - Inflammation
Kinins
Any of various structurally related polypeptides
Examples as bradykinin and kallikrein (proteases involved in coagulation).
Act locally to induce vasodilation and contraction of smooth muscles.

13. Defenses - Inflammation
Prostaglandins-
Found in most tissues and organs
Autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells.
Involved in contraction and relaxation of smooth muscle, the dilation and constriction of blood vessels, control of blood pressure, and modulation of inflammation.
Prostaglandins are derived from a chemical called arachidonic acid

14. Defenses - Inflammation
Phagocytes move to site of inflammation
Can stick to lining of blood vessels (margination)
Can squeeze through blood vessels (emigration)
Pus is the accumulation of damaged tissue and dead microbes, granulocytes and macrophages

15. Defenses - Inflammation

16. Defenses - Fever
Fever is high body temperature (>100.5°F) produced in response to infection
Fever is induced by
Endotoxins
Interleukin-1 (a cytokinin)
LPS endotoxins (exogenous)

17. Defenses – Fever - Stages
Initial chill - In the first stage of fever also known as the invasion period the patient will experience chill, loss of appetite, and headache. Chill occurs, occurs because of the tightening of blood vessels near the skin.

18. Defenses – Fever - Stages
Rising Temperature - The body is hot and flushed, the skin dry, and the pulse and respiration are rapid. The patient will experience thirst and he/she will feel restless. In high fever, delirium and convulsions may occur.

19. Defenses – Fever - Stages
Crisis - In the final stage before returning to normal, the temperature falls, breathing and pulse slow down, and the skin becomes moist. The patient often sweats.

20. Defenses – Antimicrobials Substances
The Complement System – a system of proteins which inactivate cells
Interferons – antiviral proteins

21. Defenses - Complement
A group of 8-25 serum proteins that activate one another to destroy cells
Two pathways classical and alternative
Both pathways activate protein C3 of system which binds to cell surface
Opsonization (coating bacteria –promotes phagocytosis)
Cell lysis (through further activation)
Inflammation

22. Defenses - Complement Streptococcus especially provokes inflamation
People tend to produce antibodies to cell wall rather than capsule
Peptidoglycan & teichoic acid ellicit production of IL-1 & TNFa
Opsonization would occur at cell surface but prevented by capsule
Results in escalating inflamatory response because bacteria are not cleared
Fluid accumulates in lungs disrupting gas exchange and essentially suffocating patient

23. Defenses - Complement

24. Defenses - Complement

25. Defenses - Complement

26. Defenses - Interferons
Antiviral proteins
3 types alpha, beta & gamma
Produced by virus infected cell and migrate to uninfected cells that then produce antiviral proteins
Host cell specific but not virus specific