Lines of Defense

Okay, our bodies have three lines of defense. Their names are really easy to remember, becuase they're just named 1st, 2nd, and 3rd.

1st Line of Defense: Physical and Chemical Barriers

These defenses are nonspecific and innate.

Examples: skin, mucous membranes, hair, cilia, saliva (enzymes), tears, perspiration (lysozymes), sebaceous glands (oil), gastric juices, vaginal secretions, earwax, and urine flow.

2nd Line of Defense:okay, there are four things for this category, so I'll try to organize them the best I can on this site.

I. Antimicrobial Proteins

1. Interferons-warning signals sent to nearby cells by already infected cells, that tell the cells to produce antimicrobial proteins.
2. Complement System Proteins ("helpers")-assist the immune system in a couple of ways.

               (A) They attach themselves to an invader (pathogen) and flag down T-cells and B-cells .

               (B) They create holes in bacteria (damage) so that cytoplasm leaks out.

II. Natural Killer Cells (NKCs) and Phagocytes

1. NKCs physically attack pathogens (They beat them up until they die.)
2. Phagocytes just straight up eat the pathogens. Examples of phagocytes include neutrophils and macrophages.

III. Inflammation: redness, swelling, heat, and pain.

• Causes vasodilation (which increases blood flow) and increases permeability of blood vessels.

IV. Fever

• Makes body activities happen faster.
• Kills (cooks) microbes.
• Increases blood flow.
• Increases production of interferons.

3rd Line of Defense = Specific Immunity

(1) Antigens-things that the body identifies as "foreign" and stimulate an immune response (production of anitbodies.

• i.e food allergies, bee stings, viruses, bacteria, pretty much whatever you can think of.
• Antibodies (immunoglobulins) are SPECIFIC

(2) Lymphocytes

T-cells- work via direct attack on a pathogen, or become plasma cells to produce antibodies.

B-cells- become plasma cells, which produce antibodies.

Immunological Memory-The first time you are infected with something, it might take your body days to mount a response to it. Any subsequent infections of the same pathogen may only take hours to create a response against. This is because of the presence of memory B-cells.