What is a system?

• A group of tissues (organs) that work together to do a certain task.

• Ex) digestive system, circulatory system, immune system…

• Function of the immune system is to protect your body from invasion of pathogens.

“The War on Pathogens”

• Your body is always surrounded by pathogens.

• Pathogen is ?.• Viruses, bacteria, fungi, etc.• Germ theory—infectious

diseases are caused by microorganisms of different types.

• Diseases can be passed from one person to the next are called infectious or communicable.

Non-Specific Defense

• Your body has several defense mechanisms to keep them out…..

FIRST LINE OF NON-SPECIFIC DEFENSE

1) skin

2) sweat

3) mucous membranes

4) saliva

SECOND LINE OF NON-SPECIFIC DEFENSE• inflammatory response

First Line: Skin

• Physical barrier• Chemical barrier-

secretes oil, sweat, and tears

• Sheds constantly (1 million cells per hour)

First Line: Mucus Membranes

• These line the inside of all body openings.

• Nostrils, mouth, lungs, etc.

• Cells of mucus membranes: – secrete mucus that traps

foreign objects – lined with hairs called

cilia.

• Stomach also has acid

Second Line of Defense: Inflammatory Response

• The first line of defense has been broken…

• SECOND LINE OF DEFENSE ACTIVATED: damaged cells release chemical messages that trigger a series of reactions by body-histamine

1.) capillaries to swellpuffiness

2.) increases blood flow to infected area redness

3.) temperature in area rises

4.) pain

5.) phagocytes called inget rid of pathogens

***Sometimes this response is NOT enough…

Immune System

leave room to

add more here

Immune SystemNon-specific Defense

First line:Skin

SweatMucous

Stomach acid

Second line:Inflammatory Response andPhagocytes

What if pathogens circulate through your body?

• White blood cells have to take over.• White blood cells = “soldiers” of your immune system.

The Immune ResponseSpecific Defense

• Body’s attack against a pathogen that made it past the “front lines.”

• Results in “immunity” because your immune response creates memory cells SPECIFIC for each pathogen.

• Chicken pox

IMMUNE RESPONSE

SECOND LINE OF DEFENSE:

INFLAMMATORY RESPONSE

FIRST LINE OF DEFENSE:SKIN, MUCOUS, SWEAT

NON-SPECIFIC

SPECIFIC

Organs of the Immune System

White blood cells are called leukocytesMade in the thymus (T cells) and bone marrow (B cells)Stored in tonsils, spleen, and lymph nodes.

“The Soldiers”White Blood Cells

• Leukocytes– Macrophages

– Helper T cells

– Killer T cells

– B cells

– Suppressor T cells

– Memory cells

How does your body know there is an invader?

• All pathogens have “distinct” marker proteins that are antigens.

• Antigens -anything that causes an immune response.• Your body must recognize antigens as FOREIGN

(NON-SELF) in order to create an immune response.

Step #1 “Invader Identification”Movie

• Macrophages identify pathogen as “non-self,” eat it, display the antigen, and signal for helper T cells.

• Interleukin-1 signal released= fever

• Helper T cells “signal” for the production of other leukocytes by releasing of interleukin 2.

• The next type of leukocytes called to work are known as B cells and Killer T cells.

Step #2 “Cloning Phase”• Many helper T cells, B cells and killer T cells produced.

• After B cells called up by helper T’s, they begin to produce lots of antibodies

What are antibodies?• Millions of antibodies are

made by B cells • They are like “keys” and

are specific to each antigen which are like the “locks.”

• Mark pathogen for death and can also prevent virus attachment to cell.

Step #3 “The Attack Phase”

• Pathogens marked with antibodies are destroyed by macrophages.

• Killer T cells destroy any infected body cell. Movie

Step #4 “Memory Phase”

• Macrophages act as the clean up crew, eating pathogens, damaged body cells, etc.

• Suppressor T cells “call off the troops”. They suppress, or weaken, the attack.

• Powerful memory T and B cells are left behind to “remember” the attack and quickly recognize a pathogen if it re-enters the body.

Primary vs. secondary immune response

– Primary: – 1st time in contact with

pathogen. – Takes longer for attack– Secondary: – come into contact with a

pathogen you’ve already encountered

– memory B cells are there to produce antibodies quickly and in greater amounts.

Primary response Secondary response

Immune System

Immune SystemNon-specific Defense

First line:Skin

SweatMucous

Stomach acid

Second line:Inflammatory Response andPhagocytes

Specific Defense=Immune Response

Reaction tospecific antigen

Helper T cells

Killer T cells

B cells:Antibodies and Memory Cells

Macrophage

signal

signal

Active vs. Passive Immunity

• Active Immunity (immune response, vaccine)– The body ACTIVELY produces its own

antibodies

• Passive Immunity (breast milk)– Get antibodies from mother’s milk.

Immune System FailureAllergies

• Allergy: Immune system response against a NON-PATHOGENIC antigen.

• Food, pollen, bee stings, dust mites

Immune System FailureAllergies

• Body produces more antibodies than you need, which causes release of histamine:– blood vessel dilation– swelling

• Antihistamines are in allergy medicine that reduce swelling.

• Asthma

• Movie

Immune System FailureAutoimmune disease

Immune system fails to distinguish self from non-self.

Body makes antibodies against and attacks own cells.

Examples:

MS (attack nerve cells)

Lupus (attacks organs)

Rheumatoid arthritis

(attacks joints)

Immune System FailureCancer

• One major job of the immune system is immunological surveillance.

• Killer T cells destroy our cancerous cells.

• Immune system fails to locate and remove cancerous cell, & it multiplies to form a tumor.

• Malignant tumor spreads, benign does not

AIDSAcquired Immunodeficiency

Syndrome

• Sometimes the immune system collapses totally.

• HIV (Human Immunodeficiency Virus) invades helper T cells

• B cells and killer T cells not stimulated to work—immune system breaks down!

• Body overwhelmed with pathogens

Immune System

Immune SystemNon-specific Defense

First line:Skin

SweatMucous

Stomach acid

Second line:Inflammatory Response andPhagocytes

Specific Defense=Immune Response

Reaction tospecific antigen

Helper T cells

Killer T cells

B cells:Antibodies and Memory Cells

Macrophage

signal

signal

HIV

Immune System FailuresOverreact:

Allergies Asthma

Can’t tell selffrom non self:Autoimmunedisease

Immunological surveillance doesn’t locate bad cells:Cancer Immune system

shut down due to HIV: Immunodeficiency (AIDS)

Blood types

• Each red blood cell has protein markers

• A type blood---A protein markers

• A person with type A blood makes antibodies against B markers because they are foreign

• The B markers are considered antigens to the person with A blood

Blood types

Blood types

• Universal donor: type O because no protein markers to cause immune response.

• Universal recipient: type AB because they have both A and B markers and so don’t make antibodies to either.