Earth is full of microscopic invaders that

can wage war in your body. Infectious diseases are caused by microorganisms; viruses, bacteria,

fungi, protists, or parasites. - How do you battle against such

invaders?

Immune System

• There are 3 lines of defense.• 1st line of defense (non-specific)• 2nd line of defense (non-specific)• 3rd line of defense (specific)

There are two types of defense mechanisms

Non-specificFights against any pathogens

SpecificFights against specific Pathogens and invaders

Pathogens cause disease and spread through from one person to the next by coughing, sneezing, bodily fluids, physical contact,

contaminated food, or water. How do you defeat them every day?

Non-specific immune response

• 1st line of defense against any invaders call pathogens

(1.) skin (2.) tears(3.) other secretions

Non-specific immune response

• 2nd line of defense against any invaders call pathogens

(1.) inflammatory response(2.) interferons(3.) fever

Non-specific immune response

• Inflammatory response- causes infected areas to become red and

painful, or inflamed.- the response begins when pathogens

simulate cells called mast cells to release chemicals known as histamines

Non-specific immune response

• Interferons- when viruses infect body cells, certain

host cells produce proteins that inhibit synthesis of viral proteins

- they “interfere” with viral growth; slow down the production of new viruses

Interferons

Non-specific immune response

• Fever- immune system releases chemicals that

increase body temperature- increased body temperature may slow

down or stop the growth of some pathogens / also speeds up several parts of the immune response.

Specific immune response

• 3rd line of defense- The immune system’s specific immune

defenses distinguish between “self” and “other,” and they inactivate or kill any foreign substance or cell that enters the body

Specific immune response

• Recognizing “Self” - A healthy immune system recognizes all

cells and proteins that belong in the body, and treats these as “self”

- They have the ability to recognize when something is foreign or “other”

Specific immune response

• Recognizing “Others” or “Non-self”- After encountering a specific invader, the

immune system can “remember it” in order to response more rapidly with future encounters (immune response)

- How does the immune system recognize “others”? What triggers the immune system?

**Antigens**

Specific immune response

• Antigens - Specific immune system is triggered by

molecules called antigens (foreign substance).- located on the outer surfaces of bacteria,

viruses, and parasites- the immune system responds by increasing

the # of cells that attack the invaders directly or that produce proteins called antibodies.

Specific immune response

• Antibodies- main role is to tag antigens for destruction- the body makes up to 10 billion different antibodies- the shape of antibody allows it to bind with a

specific antigen

Specific immune response

• Lymphocytes- working cells in the body

(1.) B cells – discover antigens in body fluid

(2.) T cells – discovers antigens through an infected body cells or immune cells

- Both recognize a specific antigen

How do the B cells and T cells respond?

• 2 main styles of action(1.) Humoral immunity – depends on

antibodies circulating through the blood and lymph / B cells bind to the antigen

(2.) Cell-Mediated immunity – depends on the action of macrophages and several types of T cells / T cells bind to macrophages

Acquired Immunity

• Vaccinations– The infection of a weakened form of a pathogen– Vaccinations stimulate the immune system with an

antigen. The immune system produces memory B cells and memory T cells that quicken and strengthen the body’s response to repeated infection. (active immunity)

– Antibodies that are received from other individuals that produce temporary immunity. (passive immunity) i.e. child in womb / breastmilk

Medications

• Antibiotics– Can kill bacteria, and some antiviral medications

can slow down viral activity– Have no effect on viruses, but antiviral antibiotics

inhibit the ability for the virus to multiply