Chapter 21 Flashcards
which covers and protects the body, is the body’s first line of defense
against pathogens.
skin
normally found decomposing organic matter in soil.
Pseudomonas aeruginosa
Beyond these ecological factors, the skin contains peptide antibiotics called
______ that have a wide spectrum of antimicrobial activity
- are also found in mucous membranes, especially those lining the gastrointestinal
tract
defensins
skin consists of two principal parts
epidermis and
the dermis
is the thin outer portion,
composed of several layers of epithelial cells.
epidermis
The outermost layer
of the epidermis, the _____, consists of many rows of
dead cells that contain a waterproofing protein called _____.
stratum corneum
keratin
inner, relatively thick portion of skin,
composed mainly of connective tissue
dermis
inner, relatively thick portion of skin,
composed mainly of connective tissue
dermis
provides moisture and some nutrients for microbial growth
Perspiration
capable of breaking down the cell walls of certain bacteria
lysozyme
secreted by oil glands, is a mixture of lipids (unsaturated fatty acids), proteins, and salts that prevents skin and hair from drying out
Sebum
tend to be relatively resistant to environmental stresses such as drying and the high osmotic pressures found in concentrated salt or sugar solution
Gram-positive cocci
part of the skin’s normal microbiota are gram-positive pleomorphic rods called
diphtheroids
typically anaerobic and inhabit hair follicles. Their growth is supported by secretions from the oil glands (sebum), which, as we will see, makes them a factor in acne
Propionibacterium acnes
A yeast, _____ is capable of growing on oily skin secretions and is thought to be responsible for the scaling skin condition known as dandruff
Malassezia furfur
small, fluid-filled lesions are
vesicles
Vesicles larger than about 1 cm in diameter are termed
bullae
Flat, reddened lesions are known as
macules
Raised lesions are called
papules
Raised lesions are called papules or, when they contain pus
pustules
A skin rash that arises from disease conditions is called an
exanthem
on mucous membranes, such as the interior of the mouth, such a rash is called
enanthem
Two genera of bacteria, ______, are frequent causes of skin-related diseases and merit special discussio
Staphylococcus and Streptococcus
are spherical gram-positive bacteria that form irregular clusters like grape
Staphylococci
