Transcript Skin and Mucus: Pathogens-Away!

Skin and Mucus:
Pathogens-Away!
By: Piggy G, Tiny, Reeses, and
Pikachu
Pathogen:


living organism that causes a disease
 includes: viruses, bacteria, protozoa, fungi, and worms
 (exposure doesn’t always result in disease)
Definition: An agent of disease. A disease producer. The
term pathogen most commonly is used to refer to infectious
organisms.
 Less commonly refers to a noninfectious agent of
disease such as a chemical.
 compounded from patho- meaning disease + -gen
indicating a producer.
......Hence, a disease producer.
Transmitted though: inhalation, physical contact, burrowing through
skin, body fluids, ingestion...etc.
Various Pathogens
Active vs. Passive Immunity


active immunity
 Naturally acquired
 occurs when the person is exposed to a live pathogen,
develops the disease, becomes immune as a result of
the primary immune response
 Artificially acquired active immunity can be induced by
a vaccine, a substance that contains the antigen
(vaccine stimulates a primary response against the
antigen w/o causing symptoms of the disease)
Passive immunity
 Artificially acquired passive immunity is a short-term
immunization by the injection of antibodies that are not
produced by the recipient's cells
 Naturally acquired passive immunity occurs during
pregnancy, in which certain antibodies are passed from
the mother into the fetal bloodstream.
Skin
 Skin: outer barrier to infection
 first line of defense is nonspecific
 Epidermis: upper layer (dead cells)
 Good barrier against most pathogens because
cells aren’t alive
 composed of multiple layers of tightly packed
cells, which few pathogens can penetrate on their
own
 natural shedding of dead skin cells removes many
attached microorganisms
 epidermal dendritic cells that actively patrol the
skin to phagocytize (engulf and digest) pathogens.
 Dermis: lower layer (live cells)
 beneath epidermis, contains protein fibers called
collagen
 Collagen is a tough fibrous protein, gives skin the
strength and pliability to resist abrasions that
could introduce microorganisms
...More Skin
(2 layers, 2 slides – get it? Haha!)
 Chemical Components of the Skin's Defense:
 Perspiration
Secreted by the skin’s sweat glands, contains salt and
enzymes; few microbes can live in a highly saline
environment, like skin’s surface; lysozymes in sweat
are a type of enzyme that can destroy the cell walls of
bacteria
 Sebum
Sebum secreted by skin’s sebaceous (oil) glands; oil
helps keep skin pliable, less likely to break/tear;
lowers pH of the skin to acidic level that inhibits the
growth of many types of bacteria
Mucus
mucous: mucous membrane is a part of
bodily defense like skin, but lines the inner
surface of the body; protects the body
against the acids and ph changes inside our
body; since it is a thick layer it also act as
shock absorber
mucus: lines passageways
stickiness traps pathogens preventing them
from reaching cells they could infect
secretes lysozyme which kills pathogens
See? Mucus
is good! -->
Mucous-secreting membranes line all body
cavities open to the outside environment
 Unlike the skin’s surface epidermal cells,
the epithelial cells on the outermost layer
of mucous membranes are alive
 tightly packed together, preventing entry of
pathogens into the body
 Epithelial cells continually shedding; the
discarded cells carrying away any attached
 (think about the inside of your nose...)