Phagocytes
Killer T-cells
Immunology
Macrophages
Natural Killer Cells
Immune System

Group of cells in the body that recognize
foreign substances

F(x) = to neutralize or destroy all things
“non-self” (pathogens or invaders)
What is a Pathogen?
 Any
toxin, living organism, or other
agent that can cause disease.
Immune Cells
 Immune
cells circulate throughout the
body in the blood system and the
lymphatic system
Lymphatic System
 A network
of vessels that penetrate
nearly every tissue of the body, and a
collection of tissues & organs that
produce immune cells

F(x):
Fluid
recovery from tissues
 Lymph
= fluid
Immunity
 Lymph
is filtered before returning to blood
Lymph Tissues & Organs

Lymph Nodes
 Clean the lymph & alert the immune system to
pathogens

Tonsils
 Guard against ingested or
inhaled pathogens

Thymus
 Produces T-cells

Spleen (largest Lymph Organ)
 Monitors blood for foreign objects
 Recycles old RBCs
TONSIL
Body Defense
- Two Types
1.
Non-Specific
2. Specific
Non-Specific Body Defense
 Innate
or inborn, not affected by prior
exposures
 NOT
specific for any invader
 Operates
constantly
Non-Specific Body Defense
 SKIN
– 1st Line of Defense
Physical
barrier = prevents entry of
pathogens
Must be
unbroken to
be effective
Acidic, oily,
sweat glands–
inhibits
bacterial growth
Non-Specific Body Defense
 MUCUS
MEMBRANES
Respiratory,
Digestive,
Urinary,
Reproduction tracts
F(x):
 To trap debris
& pathogens
Non-Specific Body Defense
 HAIRS
Nasal
passage
Traps debris &
pathogens
 CILIA
Upper
Respiratory
Tract
Traps debris &
pathogens
Non-Specific Body Defense
 CELLULAR
Activated
DEFENSE
when other defenses are
breached
Two
Types:
 Phagocytes
 Leukocytes
Phagocyte eating dying cells.
Phagocytes
 Cell’s
 F(x):
that recognize “non-self” items
engulf or “eat” foreign debris
 Reside
in lymph organs
 Travel
to the site of infection, via the
blood stream
Macrophage
– a type of phagocyte
Leukocytes (Natural Killer Cells)
 a.k.a.
NK Cells
 WBCs
police the blood & lymph
 F(x):
Bind
to membrane of the invader,
release chemicals, cause infected cell to
lyse
Non-Specific Body Defense
 CELLULAR
(TISSUE) DEFENSE
Inflammatory
Fever
Response
Inflammation
 Local
defensive response to tissue
injury of any kind
 Response
 Helps
is directly at site of injury
to prevent spread of the
damaging agent
Inflammation
 The
4 Signs of Inflammation – S.H.A.R.P.
Swelling
Heat
↑
All
four of these – due to fluid build-up
↓
Redness
Pain
Fever
 Abnormal
elevation in body temp.
Response
 Stimulates
 Heat
to infection
phagocytes to go to work
kills many pathogens
 Increases
the rate
of enzymatic rxns
Non-Specific Body Defense
 CHEMICAL
Interferons
DEFENSE
(antiviral proteins)

Interferons
Secreted by virus-infected cell

Stimulates non-infected cells to make
proteins that block viral protein synthesis

Slows infection to allow specific defenses to
begin working

Activates macrophages to “eat” (non-self)
viral invaders
Specific Body Defense

Immunity = ability to ward off a specific
infection or disease


Highly specific resistance to disease
Process:

Particular invader recognized
 Switches on immune response
 Invader is remembered so that future
invasions can be immediately fought
Specific Body Defense

Specific Body Defense is born out of the
Lymphatic System
Bone marrow  makes B-cells,
which make specific antibodies
i.e.
Antigens
 Irritant
or pathogen– molecule that
react with antibodies
Epitope
= region of antigen recognized
by a specific antibody
 Stimulates
formation
of antibodies
Antibodies

Molecules that react with or bind to
antigens
 Mark
antigens for destruction by
macrophages

Form due to the exposure
to a specific antigen
Antibodies
 Made
by B-cells
 Found
 Once
in plasma, & all body secretions
present, allows immediate
immune response to pathogens
Antibodies
 Structure
(most common)
 Composed
of 2 heavy chains, 2 light chains
 Constant & Variable regions
 Antigen-binding site
Variable region
Constant region
Specific Body Defense
 Helper
T-cells
Attract
other T-cells (Killer T-cells) and
macrophages to an antigen
 Killer
T-cells
Directly
attack & kill pathogens, release
chemicals to lyse cells
Specific Body Defense
 Suppressor
T-cells
Stops
immune response when antigen
is successfully overcome
Scanning Electron
Micrograph of a T-cell
Specific & Non-specific Defenses work
together to protect the body from
disease-producing pathogens

B-cells mature in bone tissue

T-cells mature in thymus tissue
Applications of Immune Response
Immunization= process that increases an
organism’s rxn to antigen & therefore
improves its ability to resist or
overcome infection.
Vaccine= living or inactivated organism
used to induce specific immunity
Vaccines
 Attenuated
agents:
Virus/bacteria
that has been
modified to be incapable of
causing disease
 Inactivated
Pieces
agents:
or a whole organism that has
been chemically inactivated
Can’t reproduce but retains antigenicity
Immunity
3
Types:
Active
Passive
Cell Mediated
Active Immunity

When an individual responds to an
antigen



Resulting from vaccination against
or
Recovery from a natural infection
Permanent Immunity
Passive Immunity

Antibodies produced from another
organism injected into the body

Temporary protection against disease
Cell-Mediated Immunity
 Killer
T-cells attack any cell not
marked with a special protein
(i.e. cells that are “non-self”)