1. Immune SystemImmune System

2. A Boo Boo lets in germsA Boo Boo lets in germs

3. Like…BacteriaLike…Bacteria

4. Or a virusOr a virus

5. A germ is still a germ….A germ is still a germ….
1.1. PathogenPathogen=agent that causes disease=agent that causes disease
22. Antigen. Antigen= foreign particle that triggers an= foreign particle that triggers an
immune responseimmune response
- often they are proteins on- often they are proteins on
the surface of viruses andthe surface of viruses and
bacteriabacteria

6. Your Body’s Defenses AgainstYour Body’s Defenses Against
DiseaseDisease
 Nonspecific Defenses: Attack allNonspecific Defenses: Attack all
pathogens and antigens the same waypathogens and antigens the same way
 Specific Defenses: Immune Response –Specific Defenses: Immune Response –
Attack pathogens that get past theAttack pathogens that get past the
nonspecific defensesnonspecific defenses

7. Nonspecific DefensesNonspecific Defenses
This means that the identity of theThis means that the identity of the
pathogen/antigen ispathogen/antigen is not importantnot important..
The response is the same if aThe response is the same if a
bacteria, virus, splinter or bulletbacteria, virus, splinter or bullet
invades the body.invades the body.

8. Nonspecific DefensesNonspecific Defenses
First Line DefensesFirst Line Defenses
 Skin: Forms a physical barrier to pathogensSkin: Forms a physical barrier to pathogens
-oils and sweat make skin acidic – inhibits-oils and sweat make skin acidic – inhibits
the growth of pathogensthe growth of pathogens
-lysozyme-enzyme found in sweat and tears-lysozyme-enzyme found in sweat and tears
digests bacterial cell wallsdigests bacterial cell walls
 Mucus Membranes-layers of tissue whichMucus Membranes-layers of tissue which
secrete mucussecrete mucus
- found in body openings and the respiratory- found in body openings and the respiratory
systemsystem
- mucus traps pathogens- mucus traps pathogens

9. Nonspecific DefensesNonspecific Defenses
Second Line DefensesSecond Line Defenses Inflammatory ResponseInflammatory Response
 Damaged cells release histamines – chemical cry for helpDamaged cells release histamines – chemical cry for help
- histamines cause blood vessels to dilate (open) bringing- histamines cause blood vessels to dilate (open) bringing
blood to the area.blood to the area.
- the dilated blood vessels become leaky releasing fluid and- the dilated blood vessels become leaky releasing fluid and
white blood cells in the infected areawhite blood cells in the infected area
- causes swelling and redness in the damaged area- causes swelling and redness in the damaged area
- pus – fluid and dead cells forms- pus – fluid and dead cells forms
 White Blood cellsWhite Blood cells
- Macrophages –- Macrophages – “Big Eaters” engulf and kill pathogens“Big Eaters” engulf and kill pathogens
- Neutrophils-- Neutrophils-engulf bactera and release chemicals thatengulf bactera and release chemicals that
kill the bacteria and themselves.kill the bacteria and themselves.
-- Natural Killer Cells –Natural Killer Cells – recognize and kill virus infectedrecognize and kill virus infected

11. Textbook page 925Textbook page 925
Histamines are released Blood vessels dilateHistamines are released Blood vessels dilate
and leakand leak

12. MacrophageMacrophage

13. Nonspecific DefensesNonspecific Defenses
Second Line Defenses (continued)Second Line Defenses (continued)
 Temperature Response -Temperature Response - Fever –Fever –
-Body temp increases in response to infection-Body temp increases in response to infection
-pathogenic bacteria don’t grow well at higher temp-pathogenic bacteria don’t grow well at higher temp
 ProteinsProteins
-- Complement Proteins:Complement Proteins: kill pathogens by punching akill pathogens by punching a
hole in the cell membranehole in the cell membrane
- Intrerferon:- Intrerferon: a protein released by cells infected by virusesa protein released by cells infected by viruses
-causes nearby cells to release an enzyme preventing the virus-causes nearby cells to release an enzyme preventing the virus
from reproducingfrom reproducing

15. Fevers help eliminateFevers help eliminate
pathogenspathogens

16. Specific DefensesSpecific Defenses
 Third Line of DefenseThird Line of Defense
Specific DefensesSpecific Defenses
- identity of pathogen/- identity of pathogen/
antigen must be knownantigen must be known
- the specific immune- the specific immune
response is tailored toresponse is tailored to
the specific pathogenthe specific pathogen

17. Specific DefensesSpecific Defenses
Macrophage Links Nonspecific to SpecificMacrophage Links Nonspecific to Specific
When a macrophage engulfs a pathogen, itWhen a macrophage engulfs a pathogen, it
displays the viral antigen on its surfacedisplays the viral antigen on its surface
The antigen is joined to a MHC
(Major Histocompatibility Complex)
The MHC is a protein on the surface of
all vertebrate cells
The anitgen must be bound to the MHC for the Helper T Cell to recognize it

18. Specific DefensesSpecific Defenses
Helper T CellsHelper T Cells
 Receptor proteins on helper T cells (TReceptor proteins on helper T cells (THH) bind to) bind to
viral antigens displayed on the macrophageviral antigens displayed on the macrophage
 causes macrophage tocauses macrophage to
release Interleukin1release Interleukin1
 Interleukin1 activatesInterleukin1 activates
the helper T cells (Tthe helper T cells (THH))

19. Specific DefensesSpecific Defenses
Helper T CellsHelper T Cells continuedcontinued
 Activated helper T cells (TActivated helper T cells (THH) release proteins called) release proteins called
cytokines which activate cytotoxic T cells (Tcytokines which activate cytotoxic T cells (TCC) and B cells) and B cells
 The activated (TThe activated (TCC) and B cells begin to divide) and B cells begin to divide

20. Specific DefensesSpecific Defenses
Cell Mediated ResponseCell Mediated Response
 Receptor proteins on theReceptor proteins on the
cytotoxic T cells (Tcytotoxic T cells (TCC) bind to) bind to
viral antigens displayed byviral antigens displayed by
infected cellsinfected cells
 Cytotoxic T cells (TCytotoxic T cells (TCC) punch a) punch a
hole in the cell’s membranehole in the cell’s membrane
 Your body produces manyYour body produces many
cytotoxic T cells (Tcytotoxic T cells (TCC))

21. Specific DefensesSpecific Defenses
Antibody Mediated ResponseAntibody Mediated Response
 B cells divide and develop intoB cells divide and develop into
plasma cellsplasma cells
 Plasma cells release large numbersPlasma cells release large numbers
of antibodiesof antibodies
 AntibodiesAntibodies bind to antigens onbind to antigens on
pathogenspathogens
 Antibodies cause pathogens to clumpAntibodies cause pathogens to clump
holding them until macrophagesholding them until macrophages
can engulf themcan engulf them
 Antibodies are specific to a particular pathogen-yourAntibodies are specific to a particular pathogen-your
body produces the antibodies in response to infectionbody produces the antibodies in response to infection

23. The Specific Defense has twoThe Specific Defense has two
phasesphases
 Primary ImmunePrimary Immune
Response:Response:
--Occurs when the bodyOccurs when the body
has never encountered ahas never encountered a
pathogen /antigen before.pathogen /antigen before.
-Immune system goes-Immune system goes
through all of the stepsthrough all of the steps
-After the threat has-After the threat has
passed,passed, MEMORY CellsMEMORY Cells
are made.are made.
 SecondarySecondary
ImmuneImmune
Response:Response:
The next time theThe next time the
pathogeninvadespathogeninvades
MEMORY CellsMEMORY Cells identifyidentify
the invader and athe invader and a
massive volume ofmassive volume of
antibodies are released,antibodies are released,
destroying the invaderdestroying the invader
before you feel ill.before you feel ill.
You are immune!You are immune!

24. VaccinesVaccines
Polio
1952 60,000 cases
in the US
3000 fatalities
1955 Salk vaccine
1979 eliminated in US

25. How do vaccines work?How do vaccines work?
 VaccinesVaccines are made up of weakened viralare made up of weakened viral
particles.particles.
 The weakened particles stimulate a smallThe weakened particles stimulate a small
number of antibodies and memory cells tonumber of antibodies and memory cells to
be produced.be produced. Primary Immune ResponsePrimary Immune Response
 When a the pathogen attacks, theWhen a the pathogen attacks, the
antibody production is larger.antibody production is larger.
Secondary Immune ResponseSecondary Immune Response

26. Immune ResponseImmune Response

27. VocabularyVocabulary
 Pathogen B cells T cellsPathogen B cells T cells
 MacrophagesMacrophages
 Nonspecific DefenseNonspecific Defense
 VaccinesVaccines
 Primary Immune ResponsePrimary Immune Response
 Secondary Immune ResponseSecondary Immune Response