1. The immune system protects the body from infection and disease through two branches - the innate and adaptive immune systems. 2. The innate immune system provides immediate defenses like white blood cells and barriers of the skin. The adaptive immune system mounts specialized defenses like antibodies and memory cells. 3. When pathogens breach these defenses, the body responds through inflammation, antibodies, and specialized immune cells like phagocytes, natural killer cells, and T cells that destroy infected cells. Immunity can be active from exposure or passive from antibodies transferred from mother to child.

1. The Human Immune System

2. What is the Immune System?
The Immune System is a complex system that is
responsible for protecting us against infections and
foreign substances.

3. Immune System : 2 branches
The Innate Immune System =
 Present at the time of birth or that develops during maturation.
The Adaptive Immune System =
 Which is acquired as a result of prior experience with a foreign
substance.

4. Cells of Immune System

5. Steam Cell: An undifferentiated cell of a multicellular
organism which is capable of giving rise to indefinitely more
cells of the same type and from which certain other kinds of cell
arise by differentiation.
Lymphoid Steam Cell: Lymphoid stem cells give rise to
the lymphocytes, which specifically identify foreign molecules
and cells.
Myeloid Progenitor: Myeloid cells include monocytes,
macrophages, neutrophils, basophils, eosinophils, erythrocytes,
dendritic cells and megakaryocytes or platelets. Lymphoid cells
include T cells, B cells, and natural killer cells.
Neutrophil: Neutrophil (also known as neutrophils or
occasionally neutrocytes) are the most abundant type of
granulocytes and the most abundant (40% to 75%) type of white
blood cells in most mammals. They form an essential part of the
innate immune system.

6. Eosinophil: A white blood cell containing granules that are
readily stained by eosin.
Basophil: A basophilic white blood cell. Basophils contain
anticoagulant heparin, which prevents blood from clotting too
quickly. They also contain the vasodilator histamine, which
promotes blood flow to tissues.
Mast Cell: A cell filled with basophil granules, found in
numbers in connective tissue and releasing histamine and other
substances during inflammatory and allergic reactions.
Memory Cell: A long-lived lymphocyte capable of
responding to a particular antigen on its reintroduction, long
after the exposure that prompted its production.
Plasma Cell: Plasma cells, also called plasma B cells,
plasmocytes, plasmacytes, or effector B cells, are white
blood cells that secrete large volumes of antibodies.

7. Viruses
Viruses and bacteria are everywhere. Some of them
want to invade our body.
Viruses enter body cells, hijack their organelles, and
turn the cell into a virus making-factory. The cell will
eventually burst, releasing thousands of viruses to infect
new cells.
Cell before infection… …and after.

8. How does our body defend
itself against Viruses and
Bacteria?

9. Defense Against Disease
If these barriers are penetrated,
the body responds with
If the innate immune response is insufficient,
the body responds with
Adaptive Immune Response
Cell-mediated immunity, Humoral immunity
Nonspecific External
Barriers
Skin, Mucous membranes
Innate Immune Response
Phagocytic and natural killer cells,
Inflammation, Fever

10. 3 lines of defense
1.First 2. Second 3. Third
Line Line Line

12. First line of defense

13. Skin
- The dead, outer
layer of skin, known
as the Epidermis,
forms a shield
against invaders and
secretes chemicals
that kill potential
invaders .
- We shed between
(40 – 50) thousand
skin cells every day.

14. - As we breathe in,
foreign particles and
bacteria bump into
Mucus throughout
our respiratory
system and become
stuck.
- Hair-like structures
called Cilia sweep
this mucus into the
throat for coughing
or swallowing.
Mucus and Cilia

15. - Swallowed bacteria are broken down by
incredibly strong acids ( HCl , NaCl , KCl ) in
the stomach that break down our food.
- The stomach must produce a coating of special
mucus or this acid would eat through the
stomach.
Stomach Acid

17. White Blood Cells
- If invaders actually
get within the body,
then our white blood
cells (WBCs) begin
their attack.
- WBCs normally
circulate throughout
the blood, but will
enter the body’s
tissues if invaders
are detected.

18. These white blood cells are
responsible for eating
foreign particles by
engulfing them.
Once engulfed, the
phagocyte (a type of cell within the
body capable of engulfing and
absorbing bacteria and other small
cells and particles) breaks the
foreign particles.

19. T-Cells
T-Cells, often called
“Natural killer” cells,
recognize infected
human cells and cancer
cells.
T-cells will attack these
infected cells, quickly kill
them and then continue
to search for more cells to
kill.

21. Antibodies
- Antibodies are large Y-shaped
protein molecules created by the
immune system to identify and
neutralize foreign objects and
pathogens, such as bacteria,
viruses, fungi, parasites, and
toxins. Also known
as immunoglobulin.
- Antibody defends the body against
a specific type of antigen ( foreign
particles).
- It is estimated that humans are
capable of generating about 10-
billion different kinds of
antibodies.

22. Antibody Production
- WBCs gobble up invading
particles and break them
up.
- Antibodies are
manufactured by white
blood cells called B-
lymphocytes, or B-cells.

23. Antibodies function:
They bind directly to antigens, effectively coating the
surface of the invader, in order to prevent pathogens
from entering or damaging healthy body cells.
Antibodies can also stimulate other parts of the
immune system (e.g. complement proteins) to destroy
the pathogens. And antibodies can mark pathogens
through a process called ’Opsonization’ so that the
pathogens can be identified and neutralized by other
immune cells.

24. Role of the antibodies:

25. What is immunity?
- Resistance to a disease causing organism or harmful
substance.
- Two types
- Active Immunity
- Passive Immunity

26. Types of Immunity

28. Active Immunity
- WE produce the antibodies
- Our body has been exposed to the antigen in the past either
through:
- Exposure to the actual disease causing antigen – we fought it, we
won, we remember it.
- Planned exposure to a form of the antigen that has been killed or
weakened – we detected it, eliminated it and remember it.

29. Vaccine
Antigens are deliberately introduced into the
immune system to produce immunity.
Because the bacteria has been killed or
weakened, minimal symptoms occur.
Have eradicated or severely limited several
diseases from the face of the Earth, such as
polio and smallpox.

30. How long does active immunity last?
It depends on the antigen.
Some disease-causing
bacteria multiply into new
forms that our body doesn’t
recognize, requiring annual
vaccinations, like the flu
shot.
Booster shot - reminds the
immune system of the
antigen.
Others last for a lifetime,
such as chicken pox.

31. Passive Immunity
We don’t produce the
antibodies.
 A mother will pass
immunities on to her baby
during pregnancy through
placenta.
 These antibodies will
protect the baby for a
short period of time
following birth while its
immune system develops.

32. Immune Disorders
Allergies
- Immune system mistakenly
recognizes harmless foreign
particles as serious threats.
- Launches immune response,
which causes sneezing, runny
nose, and watery eyes.
- Anti-histamines block effect
of histamines and bring relief
to allergy sufferers.

33. Acquired Immune Deficiency
Syndrome (AIDS)
Caused by the Human
Immunodeficiency Virus.
Discovered in 1983.
Specifically targets and kills
T-cells.
Because normal body cells
are unaffected, immune
response is not launched.

34. AIDS
- The HIV virus doesn’t kill
us – it cripples our
immune system.
- With our immune system
shut down, common
diseases that our immune
system normally could
defeat become life-
threatening.
- Can show no effects for
several months all the way
up to 10 years.

35. Autoimmune Diseases
Our body's immune system protects us from
disease and infection. But if we have an
autoimmune disease, our immune system
attacks healthy cells in our body by mistake.
Depending on the type, an autoimmune
disease can affect one or many different types
of body tissue. It can also cause abnormal
organ growth and changes in organ function.
There are as many as 80 types of autoimmune
diseases.

36. Causes of Autoimmune Diseases:
The cause of autoimmune disease is unknown. There are
many theories about what triggers autoimmune diseases,
including:
bacteria or virus
drugs
chemical irritants
environmental irritants

37. Common Autoimmune Diseases:
Rheumatoid Arthritis: inflammation of joints
and surrounding tissues.
Systemic Lupus Erythematosus: affects skin,
joints, kidneys, brain, and other organs.
Type 1 Diabetes: destruction of insulin
producing cells in the pancreas.
Reactive Arthritis: inflammation of joints,
urethra, and eyes, may cause sores on the skin
and mucus membranes.

38. How are Autoimmune Diseases treated?
eat a balanced and healthy diet
exercise regularly
get plenty of rest
take vitamin supplements
decrease stress
Medical interventions include:
hormone replacement therapy, if necessary
blood transfusions, if blood is affected
anti-inflammatory medication, if joints are affected
physical therapy