Question

Which of the following best describes an example of a nonspecific external response to harmful bacteria?

Phagocytes engulf and destroy invading bacteria.

Histamine causes areas invaded by bacteria to swell.

Antibodies recognize bacteria and attack them.

Enzymes in saliva break down bacterial cell walls.

Answer 1

please help me

Answer 2

(X) Antibodies are SPECIFIC; they bind to a 'lock-and-key' like fashion to a SPECIFIC antigen. [Antibodies are like the super-hero (key) and antigen is your villain or unidentified/foreign invader. Of course, antibodies are more like markers--marking the antigen as a foreign invader and other players in your immune sys (like phagocytes) will take care of them (eat them up). For an antigen to get 'marked' by an antibody (specific to them and all their buddies) is like a death sentence --via phagocytosis.

Answer 3

OK, I got it! Key Word: EXTERNAL

(X)Phagocytes are INTERNAL,NON-specific

(X)Histamine are INTERNAL, NON-specific

(X) Antibodies are INTERNAL, SPECIFIC

(CORRECT) Enzymes in saliva break down bacterial cell walls
= EXTERNAL, NON-specific response

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The enzyme lysozyme digests cell walls of many bacteria (thereby, destroying them).
The skin barrier @ this point has not yet been compromised --(remember epithelium lining digestive tract spanning from the mouth to the anus is also part of your skin barrier to the external environment).

*Histamine is released by basophils (special leukocytes) and by mast cells in connective tissue. At this point, skin barrier [EXTERNAL] has been compromised and [INTERNAL] non-specific response has been activated: inflammatory.

Inflammation on your *visible* skin is something you can see has swollen and physically touch and itch, but it is a response initiated by internal defenses. Also keep in mind that inflammation can also occur to our internal organs. This might help you remember that it is not an external immune response.