Important system that helps fight off Important system that helps fight off pathogenspathogens

What is a Pathogen?

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

Bacteria Viruses Fungi Protists/ParasitesBacteria Viruses Fungi Protists/Parasites Made of many cells each with a specific job Made of many cells each with a specific job

including:including:

a. a. LymphocytesLymphocytes – –

White blood cellsWhite blood cells or or WBCWBC

Target specific Target specific PathogensPathogens

Immune Immune SystemSystem

Types of Types of LymphocytesLymphocytesT cells - Identify Pathogens by

recognizing their Antigens

B cells - Produce chemicals called

Antibodies

Macrophages – Surround pathogen and digest or

eat it Also called Phagocytes

PathogensPathogens

Types of Types of LymphocytesLymphocytes What are Memory CellsWhat are Memory Cells ??

Remember what type of antigens a pathogen Remember what type of antigens a pathogen hashas

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

invades our body again!! AMAZING ! ! !invades our body again!! AMAZING ! ! ! What are the Types of T – Cells?What are the 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

ANTIGENS AND ANTIGENS AND ANTIBODIESANTIBODIES What are What are Antigens?Antigens?

Special proteins on surface of cells and Special proteins on surface of cells and pathogenspathogens

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

Why?Why?

So that the So that the White blood cellsWhite blood cells know which know which

pathogens they need to destroy!!!pathogens they need to destroy!!!

What are What are Antibodies? Antibodies?

Special proteins that recognize specific Special proteins that recognize specific AntigensAntigens on on PathogensPathogens

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

PathogensPathogens 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 Staph?pathogen is Staph?

BACTERIABACTERIA

4 4 TYPESTYPES OF COMMON OF COMMON PATHOGENSPATHOGENS Can you guess what they are? Can you guess what they are?

Viruses Fungi Bacteria Viruses Fungi Bacteria Protists/ParasitesProtists/Parasites

11. . VirusesViruses Flu HIV Measles Flu HIV Measles

VirusVirus

2.2. Fungi Fungi

Athlete’s Foot Athlete’s Foot

Candida albicans Candida albicans FungusFungus

44 TYPES OF COMMON TYPES OF COMMON PATHOGENSPATHOGENS

3. 3. BacteriaBacteria

STAPH STAPH BacteriaBacteria

Strep throatStrep throat

4. Protists4. Protists Paramecium Paramecium

GiardiaGiardia

GiardiaGiardia

The Immune The Immune SystemSystem

• The immune system includes The immune system includes T cellsT cells and and B cellsB cells..

• The cells work together to fight The cells work together to fight infections.infections.

• How does the immune system work? How does the immune system work? Let’s find out!!Let’s find out!!

T-CellsT-Cells have more than one job have more than one job

One job may be to……………One job may be to……………What happens when a virus What happens when a virus

infects a cell?infects a cell?

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

So, why do So, why do B–cells B–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 antigen.

Some T cells attack cells infected with pathogens.

Other T cells signal B cells to produce antibodies .

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

Antibodies help macrophages destroy the bacteria or virus

Two Types of Two Types of ImmunityImmunity

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 to Antibodies are injected into a patient to

help prevent a disease from a pathogenhelp prevent a disease from a pathogen

VaccineVaccine

Contain a weakened pathogen that Contain 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 Active Immunity Both Passive ImmunityPassive Immunity

The body makes

antibodies.

Memory cells recognize antigensfrom the

pathogen.Immunity

may last for years or a lifetime.

Antibodies are given; the body does not

make antibodies.Immunity can be

acquired from the mother

during pregnancy.

Immunity lasts only a few months.

Can prevent diseases

May involve

an injection

Review Questions1. Question: What is the function of the

immune system? Answer: Helps fight off pathogens.

2. Question: Which 3 white blood cells or lymphocytes help destroy pathogens?

Answer: Macrophages, B cells and T cells

3. Question: What is an antigen? Answer: Special protein on surface of

pathogens recognized by the

immune system

4. Question: What is an antibody? Answer: Special protein in the immune

system that recognizes and attaches to a specific antigen on a pathogen and marks it for destruction.

5. Question: Explain the difference between Active and Passive Immunity?

Answer: * In Active immunity the immune system produces the antibodies.

* In Passive immunity the

antibodies are injected into a patient to

destroy the pathogens

6. Question: Which cells of the immune system produce

antibodies?

Answer: B cells

7. Question: Which cells produce B cells?

Answer: T cells

8. Question: What are memory cells?

Answer:

Remember what type of antigens a 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 againpathogen if it invades our body again!!!!

9. Questions: What are the 4 main functions of T-cells

Answer:

1. Destroy pathogens after they are marked by1. Destroy pathogens after they are marked by

AntibodiesAntibodies

2. Destroy cells that are infected with a virus2. Destroy cells that are infected with a virus

3. Also recognize cancer cells and destroy 3. Also recognize cancer cells and destroy themthem

4. Stimulate B-cells to produce antibodies4. Stimulate B-cells to produce antibodies

10. Question: What are the 4 common pathogens?

Answer: Virus Bacteria Fungi Protists/parasites