Mucus acts as a physical barrier to foreign pathogens in the following ways: Mucus traps pathogens trying to enter the body through various openings. It entangles them and slows their movement. Mucus also contains antibodies and enzymes that can destroy pathogens. Finally, mucus is constantly moved by cilia up and out of the body, sweeping pathogens away from vulnerable tissues.

1. Entry slip: How does mucus act as a physical barrier
to foreign pathogens?
Lesson 4.13- Describe the physical body’s response
to viruses/fungi/bacteria, vaccines, and allergens.
(pp383-386) of Biology-McGraw-Hill Ryerson)
I. Terms:
a.Leukocyte: WBC
b. Antigens: chemical signals on the surface
of cells and foreign pathogens
c. Antibodies: small chemical designed to
attach to and neutralize certain antigens
d.Induce: to give
e.Shock: a medical emergency where a
person can die due to blood loss.
f. Anti-histamines: medications taken by a
person with a allergic reaction.
II. Response to viruses/fungi/bacteria:

2. a. Phagocytic leukocytes: engulf and destroy
foreign pathogens
b. Non-phagocytic leukocytes: some WBC’s
release “histamines” that cause the
inflammatory effect
i. One effect of inflammation is
increased temperature. Sometimes
this is enough to kill the foreign
pathogens.
c. Lymphocytes: create “trained antibodies”
that recognize and kill similar foreign
pathogens in the future. We call this
NATURAL IMMUNITY
i. When a leukocyte has a virus inside it
and is digesting it, some of the virus’
antigens are displayed on the
leukocyte’s surface.
ii. A lymphocyte attaches to this, and
“downloads” information from the
pathogen.

3. iii. The information that the lymphocyte
gets instructs it how to make many
anti-bodies that will kill a similar
pathogen.
iv. These antibodies float in blood
plasma and kill any foreign pathogens
that it recognizes in the future.
III.Response to vaccines:
a.Vaccines are created in laboratories by
medical staff who deal with deadly
diseases.
i. The scientists separate the antigens
from the surface of the
virus/bacteria/fungus
b.Vaccines are swallowed or injected into
the patient.
c. Inside the body, the lymphocytes get to
work “downloading” information from
the vaccine’s antigens and created
antibodies to destroy anything with those

4. antigens in the future, such as H1N1 virus,
HPV, or even the common cold.
d. We call this INDUCED IMMUNITY
IV.Response to allergens:
a.Some of us are sensitive to certain
substances that pose no threat to our
health, such as pollen or mould.
b.Certain antibodies cause histamines to be
released, to initiate, or start, the
inflammatory response (redness, swelling,
pain, warmer temperature, and loss of
function)
c. Some of these major signs of an
inflammatory response can kill us:
i. The swelling is due to vasodilation,
which increases the permeability of
the blood vessels. Sometimes, so
much blood plasma leaves the blood
vessels that the blood cannot be
circulated properly, and the person
dies from “shock”.

5. ii. If the swelling occurs in the trachea/
bronchi or bronchioles, we can
suffocate.
d. Anti-histamines, if taken in time, will slow
down the rate at which histamines are
being released into the blood and will
stop vasodilation.
e.Severe allergic reactions will occur when
there is major vasodilation and immediate
blood plasma movement out of the
vessels’ walls: this is called anaphylaxis.
The Epi-Pen® is an injector that gives a
person a dose of epinephrine: a synthetic
form of adrenaline. Remember that
adrenaline is a vaso-constrictor and will
decrease the permeability of blood
vessels’ walls.
V. Youtube search:
a. Be Safe from Anaphylaxis-Mayo Clinic
b.Anaphylactic allergic reaction
c. Allergic Reaction-khurst1

6. VI.Homework:
a.None-take a break!