Immune SystemImmune System• Important system that helps fight offImportant system that helps fight off pathogenspathogens

• What is aWhat is a Pathogen? Pathogen?

• Microorganism that causes infection or a disease:Microorganism that causes infection or a disease:

Bacteria Viruses Fungi Protists/ParasitesBacteria Viruses Fungi Protists/Parasites

• Made of different types of cells each with a Made of different types of cells each with a

specific job including:specific job including:

a.a. LymphocytesLymphocytes – –

White blood cellsWhite blood cells or or WBC’sWBC’s

Target specificTarget specific PathogensPathogens

Types ofTypes of LymphocytesLymphocytes b. b. T - cellsT - cells Identify Identify PathogensPathogens by recognizing by recognizing their their Antigens.Antigens. What is their job? What is their job? To activateTo activate B-cellsB-cells c. c. B cellsB cells Produce chemicals called Produce chemicals called AntibodiesAntibodies d. d. Macrophages Macrophages –– Surround pathogen and digest Surround pathogen and digest or eat itor eat it Also calledAlso called PhagocytesPhagocytes

PathogensPathogens

Types ofTypes of LymphocytesLymphocytes• What are the Two Types of T– Cells?What are the Two Types of T– Cells?

1. Natural Killers Cells 1. Natural Killers Cells

2. Cytotoxic Cells 2. Cytotoxic Cells

* Destroy pathogens after they are marked by* Destroy pathogens after they are marked by

antibodiesantibodies

* Destroy cells that are infected with a virus* Destroy cells that are infected with a virus

* Also recognize cancer cells and destroy them* Also recognize cancer cells and destroy them• What are Memory T- Cells What are Memory T- Cells ??

They remember what type of antigens on a pathogen They remember what type of antigens on a pathogen

Help immune system recognize the pathogen if itHelp immune system recognize the pathogen if it

invades our body again!! AMAZING ! ! !invades our body again!! AMAZING ! ! !

ANTIGENS AND ANTIBODIESANTIGENS AND ANTIBODIES• What are Antigens?What are Antigens?

Special proteins on surface of cells and pathogensSpecial proteins on surface of cells and pathogens

They are recognized by theThey are recognized by the Immune SystemImmune System

• Why?Why?

So theSo the White blood cellsWhite blood cells know which pathogens know which pathogens they need tothey need to destroy!!!destroy!!!

• What are Antibodies? What are Antibodies?

Special proteins that recognize specific Special proteins that recognize specific AntigensAntigens

on on PathogensPathogens

Mark the pathogens for destruction byMark the pathogens for destruction by WBC’sWBC’s

PathogenPathogenss

• What are Pathogens?What are Pathogens?

Organisms that cause Organisms that cause diseasedisease

• Infectious diseases Infectious diseases are?are?

Diseases that are Diseases that are caused by pathogens .caused by pathogens .

• When you have an When you have an infectious disease infectious disease pathogens are inside pathogens are inside your body causing your body causing harmharm

• Staphyloccocus Staphyloccocus aureusaureus

• Magnified 20,000XMagnified 20,000X• About 1 um in sizeAbout 1 um in size

• What type of What type of pathogen is pathogen is Staph?Staph?

BACTERIABACTERIA

44 TYPES OF COMMON TYPES OF COMMON PATHOGENSPATHOGENS

• Can you guess what they are?Can you guess what they are?

Viruses Fungi Bacteria Viruses Fungi Bacteria Protists/ParasitesProtists/Parasites

1. 1. VirusesViruses Flu HIV Measles Flu HIV Measles

VirusVirus

2. 2. FungiFungi

Athlete’s Foot Athlete’s Foot

Candida albicansCandida albicans FungusFungus

44 TYPES OF COMMON TYPES OF COMMON PATHOGENSPATHOGENS

33. . BacteriaBacteria

STAPH STAPH BacteriaBacteria

Strep throatStrep throat

4. 4. ProtistsProtists Paramecium Paramecium GiardiaGiardia

GiardiaGiardia

The Immune The Immune SystemSystem• The immune system includesThe immune system includes T cellsT cells

and and

B cellsB cells..• The cells work together to fight The cells work together to fight

pathogenspathogens

and help destroy and help destroy CancerCancer cells cells• How does the immune system work? How does the immune system work?

Let’s Let’s

find out!!find out!!

What happens when a virus infects What happens when a virus infects a cell?a cell?

What do T-cellsWhat do T-cells do?do?

What is another job of theWhat is another job of the T- T- cells?cells?

So, why doSo, why do B – cellsB – cells produce produce antibodies?antibodies?Because……Because……

ImmunityImmunityHow does a person become How does a person become

immunized?immunized?

How does the Immune System How does the Immune System workwork

T- cells recognize bacterial or viral T- cells recognize bacterial or viral antigen.antigen.

Some T- cells attack cells infected with Some T- cells attack cells infected with pathogenspathogens

Other T-cells signal B cells to produce Other T-cells signal B cells to produce antibodiesantibodies .

Antibodies attach to the antigens on virus or Antibodies attach to the antigens on virus or bacteria bacteria (Lock & Key)Lock & Key)

Antibodies help phagocytes destroy the bacteria Antibodies help phagocytes destroy the bacteria or virusor virus

Two Types of ImmunityTwo Types of Immunity• Active ImmunityActive Immunity Immune system produces antibodiesImmune system produces antibodies

on its own in response to a pathogenon its own in response to a pathogen

• Passive ImmunityPassive Immunity Antibodies are injected into a patient Antibodies are injected into a patient

to to

help prevent a disease from a help prevent a disease from a pathogenpathogen

• VaccineVaccine Contains a weakened pathogen that Contains a weakened pathogen that

stimulates production of antibodies stimulates production of antibodies without causing the actual disease, without causing the actual disease, or…………?or…………?

Antibodies are already in the vaccineAntibodies are already in the vaccine

Active Immunity Both Passive ImmunityActive Immunity Both Passive Immunity

The body The body makes makes

antibodies.antibodies.

Memory cells Memory cells recognize recognize antigensantigensfrom the from the

pathogenpathogen.Immunity Immunity

may last for may last for years or a years or a lifetime.lifetime.

Antibodies Antibodies are given, are given, the body the body does not does not

make make antibodies.antibodies.Immunity can be Immunity can be

acquired from the acquired from the mother during mother during

pregnancy.pregnancy.

Immunity Immunity lasts only a lasts only a few monthsfew months..

Can Can prevent prevent diseasesdiseases

May May involve involve

an an injectioninjection

Review QuestionsReview Questions1.1. Question Question: What is the : What is the functionfunction of the of the immune immune

systemsystem??

Answer: Helps fight off pathogens.Answer: Helps fight off pathogens.

2. 2. QuestionQuestion:: Which 3 Which 3 white blood cellswhite blood cells or lymphocytes or lymphocytes

help destroy pathogens?help destroy pathogens?

Answer: Macrophages, B cells and T cellsAnswer: Macrophages, B cells and T cells

3. 3. QuestionQuestion: What is an antigen?: What is an antigen?

Answer: Answer: Special proteinSpecial protein on surface of pathogens on surface of pathogens

recognized by the recognized by the immune systemimmune system

4. 4. QuestionQuestion: What is an antibody?: What is an antibody?

Answer: Special Answer: Special proteinprotein in the immune in the immune system system that recognizes and that recognizes and attaches to a attaches to a

specific specific antigenantigen on a pathogen and on a pathogen and

marks the pathogen for destruction.marks the pathogen for destruction.

5.5. QuestionQuestion: Explain the difference between : Explain the difference between Active Active

and and Passive ImmunityPassive Immunity??

Answer: * In Answer: * In Active immunityActive immunity the immune the immune

system produces the antibodies. system produces the antibodies.

* In * In Passive immunityPassive immunity the antibodies the antibodies

are injected into a patient to destroyare injected into a patient to destroy

the pathogensthe pathogens

6. 6. QuestionQuestion: Which cells of the immune system : Which cells of the immune system produce antibodies?produce antibodies? Answer: B cellsAnswer: B cells7. 7. QuestionQuestion: Which cells produce B cells?: Which cells produce B cells? Answer: T cellsAnswer: T cells8. 8. QuestionQuestion: Name the 2 types of : Name the 2 types of T- cellsT- cells Answer: Answer: 1) Natural Killer cells 1) Natural Killer cells 2) Cytotoxic cells2) Cytotoxic cells9. 9. QuestionQuestion:: What are memory What are memory T - cells?T - cells? Answer: Answer: * They remember what type of antigens a* They remember what type of antigens a pathogen haspathogen has * Help immune system recognize the * Help immune system recognize the pathogen if it invades our body again!!pathogen if it invades our body again!!

10. 10. QuestionQuestion: What are the 4 main functions of : What are the 4 main functions of T- cellsT- cells

Answer:Answer:

* Stimulate B-cells to produce antibodies* Stimulate B-cells to produce antibodies

* Destroy pathogens after they are marked * Destroy pathogens after they are marked

by antibodiesby antibodies

* Destroy cells that are infected with a virus* Destroy cells that are infected with a virus

* Also recognize cancer cells and destroy them* Also recognize cancer cells and destroy them

11. 11. QuestionQuestion: What are the : What are the 4 common4 common pathogens? pathogens?

Answer: Answer:

Virus Bacteria Fungi Protists/parasitesVirus Bacteria Fungi Protists/parasites

::

12.12. QuestionQuestion: Name 2 ways a vaccine works!: Name 2 ways a vaccine works!

Answer:Answer:

1. Contains a weakened pathogen that stimulates 1. Contains a weakened pathogen that stimulates

production of antibodies without causing the production of antibodies without causing the

actual disease, or…………?actual disease, or…………?

2. Antibodies are already in the vaccine to 2. Antibodies are already in the vaccine to

destroy pathogens, body doesn’t need to make destroy pathogens, body doesn’t need to make

antibodiesantibodies

13.13. QuestionQuestion: Why : Why can’tcan’t scientists produce an scientists produce an

effective vaccine against effective vaccine against HIVHIV??

Answer: Because the virus mutates or changes Answer: Because the virus mutates or changes

and the vaccine no longer works!!!!!and the vaccine no longer works!!!!!