Immune System

Functions include defense against invading pathogens and clearing cellular debris

There are two parts, the innate primary defense system, which is non specific, and the adaptive defense system, which is specific.

Primary Innate System

First Line Of Defense:

Surface Barriers-

A). Skin

1). Barrier because of keratin

2). Acidity of skin secretions

-both mechanical and

chemical tools are in place

from birth

Primary Innate System

Second Line of Defense:

Mucous Membranes-Cover all body cavities with

exterior openings.

1). Sticky mucus

2). Stomach:  HCl and protein

digesting enzymes.

3). Saliva & lacrimal fluids:

bacteria destroying enzymes.

4). Nasal hairs

5). Cilia

6). Acidity of the vagina

7). Acidity of urine

Primary Innate System

Pathogens that get through the skin and mucosae are confronted by phagocytes.

Phagocytes are macrophages that derive from monocytes that leave the bloodstream and enter the tissue and develop into macrophages.

Neutrophils become phagocytic upon encountering a pathogen.