2.  We are in constant contact with foreign
substances “nonself”.
 These substances are called disease-
causing agents or pathogens
 Pathogens include
viruses, fungi, bacteria or parasites.

8. Our body in the first place prevent the entry
of these pathogens by :
1- Integumentary system defense:
2- Respiratory system defense
3 - digestive system defense

9.  Consists of:
 1- skin : it’s the barrier between the inside
and outside of the body.
 2- tears : wash the eyes and hold up
materials that slow down the growth of
pathogens.
 3- sweat: its acidic, bad medium for
pathogens
 4-bacteria: found on our skin kill some
pathogens

10.  Including:
 1-sneezing and coughing releases
pathogens outside.
 2-Cilia: hair-like protrusions in nose and
lungs, which traps dust.
 3- mucus: is a thick slippery substance in
nose, throat, lungs. Pathogens stick on
this material till the body gets rid of it.

12.  Includes
 1- saliva in our mouth
 2- High acidity in our stomach
 3-Liver and pancreatic enzymes
 4-mucus along the lining ; works in
trapping.
Mucus is also found in our urogenital tract.

14. IF the first body barrier get past and now
pathogens are inside the body’s
circulatory system, the body then uses
it’s Immune system respond.
This respond is done by a group of immune
cells and organs.

15.  1- Bone marrow: produces WBC
 2-Thymus: mature WBC
 3- Spleen: battle site
 4- lymph nodes + lymphatic vessels.

17.  1- are specialized white blood cells
 WBC are divided in to:
• B cells ─≥ plasma ─≥ produces antibody.
• T cells: a- T helper which induce other cells
to work
b- T killer which directly destroy an infected
cell.
c- Phagocytes: or antigen presenting cells,
they phagocyte or eat pathogen and
present it’s particles on it’s surface .
d- mast cells release histamine,

24.  During an immune response WBC
increase in number. Immune cells
circulate in the circulatory and
lymphatic system but mainly in the
lymphatic system.

25.  It transports lymph: containing pathogen
fighting WBC, lymph moves through the
lymphatic vessels (like veins) to the
damaged tissue.
 Lymph drift through lymphatic vessels
when our skeletal muscles contract (or
when we move), it has no pump system.

27.  Lymph moves through lymph nodes
which filters out pathogens and store
WBC + antibodies that’s why when your
sick your nodes swell.

28.  There is two types of immune response:
1- specific : its against specific antigen ;
and its permanent
2 – Nonspecific response: like inflammation
and allergy; its against any foreign body.
It is temporary.

29.  Inflammation: it’s the bodies first defense
against injuries and infection
 Symptoms: swelling,redness,and heat.
 When tissue is irritated or damaged,
histamine is released causing a raise in
temperature and increase blood flow to
the area, thereby allowing more
RBC,WBC and antibodies to reach
quicker.

30. High temperature increase the speed of
WBC and weakens pathogens.
If many tissues are affected; histamine will
be every where, as a consequence the
whole body temp will rise above 37
which we call FEVER
This temperature must be lowered or it will
cause tissue damage.
Medicine is advisable

33.  The body first detects a foreign antigen..
 It performs a specific immune response
 This response provide protection from
future exposure to this antigen.

34.  When the body recognizes a foreign
antigen ,B and T cells divide rapidly in
huge numbers but not all of them fight
the battle but some are kept as memory
cells for future exposure to the same
antigen,
 So that upon the second entry of the
same antigen the body will directly
respond in shorter and more effective
way.

36.  Antibodies hold tight the antigen
marking it for T killers, chemicals or other
immune cells to get rid of it

40.  Is the resistance to sickness.
 It is accomplished through the memory B
cells which are kept in your body .
These B cells already recognized the
pathogen during its first entrance so now
its ready to release antibody directly and
destroy this pathogen, so that we don’t
even get ill.

41.  Immunity could be:
 1- active: its when your body makes its
own antibody. It will be ready for the
next exposure to the same pathogen.
 2-passive: antibodies are not produced
by the body itself but are transmit or
delivered to the person. Example when
the mother breastfeed her child.

42.  Our body takes time to develop a
defense against certain pathogen.. So
the disease will be able to cause
significant and lasting damage before it
is defeated.
 Other pathogens are so strong that
immune system cant respond.
Medication is suitable in this case.

43.  VACCINATION: it’s a way to develop
immunity using vaccine.
 Vaccine is an injection of a dead or
weekend pathogen which upon
injection it stimulates our immune
response to produce antibodies while
we stay healthy.
 Vaccination protects babies and adults
from their grandparents ilness.It could be
taken by mouth or as an injection.

45.  It could be used to decrease the symptoms
of a disease or prevent further damage of
tissue but cant defend the pathogen.
 Medicines are effective to destroy
pathogen: example :antibiotics: are
medicines that block the growth and
reproduction of bacteria.
 We use them in case of step throat or ear
infection.
 Other medicines are used to cure diseases
coming from viruses, fungi or parasites.