physiology notes:

Notes: Immune System

1. Role of:

a. Neutrophils: act as phagocytes against antigens

b. Eosinophils: detoxification; can break down clots; defense against worm

parasites and ↑during allergy infections

c. Basophils: contain histamines; may also release heparin, an anticoagulant

d. Monocytes: Phagocytic; can develop into macrophages in connective tissue

e. Lymphocytes: produced in bone marrow; stored in lymphatic tissue

-B cells: produce antibodies; humoral response

-T cells: kills cells directly

2. Nonspecific immunity: defenses that attack all pathogens that have not specificity; mediated by leukocytes that are not lymphocytes.

3. Phagocytosis: when immune system cells wrap their membranes around the pathogens and encase them in a vacuole; these may be neutrophils, monocytes, or macrophages.

4. Chemotaxis: using a chemical signal that attracts leukocytes to the site of the invading microbe.

5. Diapedesis: ability of phagocytic cells form blood to squeeze out of blood capillaries into infected tissue to fight invaders.

6. Role of interferons: small proteins released by cells invaded by viruses to help block protein synthesis in other cells and thus interfere with the viral replication process.

7. Fever: high body temperature can increase the activity of neutrophils and ↑ production of interferons; fever also ↓ availability of zinc and iron that bacteria need for their metabolism.

8. Endogenous pyrogens: produced by monocytes and macrophages; act on hypothalamus to increase body temperature→ fever.

9. Specific immunity: mediated by lymphocytes; attack specific microbes; antibodies and memory cells involved.

10. Antigen: specific protein substances that stimulate the production of antibodies.

11. Antigenic determinant: the specific portion of the antigen that the antibody will bind with.

12. Antibodies: (immunoglobins) are the gamma globulin portion of blood proteins; produced by B cells (plasma cells); contain heavy and light chains, variable and constant regions; inactivate antigens.

13. Structure of antibody: Y-shaped; constant regions are same in all; variable region designed to fit a specific antigenic determinant; somatic recombinations produce over 1 billion gene arrangements to combat the high number of antigens.

14. B lymphocytes: activated by direct contact with antigens; they become plasma cells→ antibodies.

15. Complement system: 11 proteins from liver that bind with antigen; puncture bacterial membrane and destroy the bacteria cell

16. Reactions:

a. Chemotaxis: attraction of phagocytic cells to infection site

b. opsonization: coating the walls of the bacteria to allow for adherence by leukocytes

c. Histamine release: from mast cells; causes vasodilation and capillary permeability to allow more phagocytic cells to enter infected cell→ inflammation

d. Inflammation: ↓ spreading of invading agents to adjacent tissues; rids tissues of pathogens; helps repair

17. Active immunity: recognition of previous invaders (memory cells); allows rapid response to invasion.

18. Primary response: first exposure→ 5 to 10 days for antibody production.

Secondary response: maximum antibody response= 2 hours; immune response.

19. Clonal selection theory: B cells → antibodies against specific antigen; memory cells remain in body

20. Plasma cells: formed from B cells; produce antibodies

21. Killer T cells: actively destroy bacterial cells, viral infected cells, and tumor cells; Produce perforins that make holes in cell membranes.

Helper T cells: enhance activity of B cells and Killer T cells

Suppressor T cells: shut down activities of B cells and Killer T cells after infection is arrested.

22. Lymphokines; secreted by T cells; activate killer T cells and macrophages; some activate B cells.

23. T lymphocyte activation: T cells do not bind to antigens; must have an antigen presenting cell (macrophage)

Macrophages engulf antigens; their lysosomes move to cell surface with antigen exposed; histocompatibility molecules determined if foreign; a complex forms;

T cells then activated

24. Histocompatabiliy: cell surface proteins serving as markers; MHS class I on all cells, class II on leukocytes.

25. Allergic reaction: allergen stimulates release of histamine from mast cells (cross binding of allergen with IgE molecules attached to mast cells); produces edema, mucous release, constriction of respiratory passages.

26. Anaphylatic shock: may be life threatening; circulatory collapse, bronchioles constrict, swelling of tongue; relieved by epinephrine.

27. Monoclonal antibodies: specific antibody fused with cancer cell→ hybridoma; when hybridoma divides, it produces more of the antibody.