Fighting Diseases

Causes of Disease

 many diseases are caused by microorganisms, called

pathogens

 they enter the body (called an

antigen

) and either damage tissues or produce substances that toxic to the body  the body combats disease through the immune system

The Immune-System Response

 the human body have many defenses against infection  They are categorized into THREE lines of defense: 1.

External (integumentary system) 2.

3.

Non-specific (Innate) Immunity Specific Immunity

1 st Line of Defense Integumentary System

 the first line of defense is an external or physical barrier 

the human skin

, if unbroken, forms an almost impenetrable barrier against microorganisms  cells in the nasal passages and pharynx secrete sticky

mucus

that traps microorganisms and digestive enzymes in the mucus can destroy most microorganisms

2 nd Line of Defense Non-specific (Innate) Immunity

 if invaders get pass the 1 st line of defense and enters the body, the 2 nd line of defense, a complex network of organs, works to get rid of the infection Lymphatic system

2 nd Line of Defense The Lymphatic System

 white blood cells (called

leukocytes

) seek out and destroy invaders and are produced in the lymph nodes  Three types of defending leukocytes:    Macrophages (“big eaters”, pus) – engulf antigens Neutrophils - engulf antigens Natural killer (NK) cells – kill invaded cells

Macrophage – “Big Eater”

 “fishing” for bacterial with long, sticky cytoplasmic extensions

Inflammatory Response



Histamine release

– increases blood flow 

Increase capillary permeability

:  Edema – swelling, pressure on nerves = pain  Immune cells circulate better 

Elevated temperature

– fever, helps with attack against pathogens

3 rd Line of Defense Specific Immunity



Lymphocytes

(another class of leukocytes) can recognize antigens and direct an immune response B lymphocytes (

B cell

) antigen T lymphocyte (

helper T cell

)

3 rd Line of Defense Specific Immunity



B cells

– produce and display

antibodies

(Plasma B cells)

,

and some also become

memory B cells

 antibodies are protein molecules that protect the body from invaders by attaching to the surface of the invader which makes it more easily identifiable to macrophages  antibodies are unique to each antigen form a response against

antigens

, the surface of an invader may have many different antigens



Helper T cells:

 release cytokines that activate more B cells, Killer T cells, and macrophages  Kill viruses with toxins

After the infections is over:

- B cells and T cells die, except for memory B cells

T-Killer cells a.k.a. cytotoxic T cells

 Match the template with the viral antigen and kill the virus with toxins; also kill cancer cells

Active Immunity

 lasting protection against pathogens through the production of antibodies  can be acquired naturally, when a person recovers from an invaders and has produced antibodies against it

OR

 artificially, by the injection of

vaccines

made of dead or weaken invaders, or even isolated antigens, the body will produce antibodies to provide immunity towards the pathogen

Prevention of Disease Summary

 Proper

sterilization

and/or cleaning of instruments & surfaces 

disinfectants

(chemical that kill microorganisms on surfaces) E.g., bleach  Proper use of

antiseptics

used on the skin) (chemicals that can be  e.g. mouthwash, antibacterial soap  Proper use of

antibacterial medication



Vaccinations

(dead form of pathogen)  Natural human

immune response

Let’s see this all in action The Immune Response

http://highered.mcgraw hill.com/classware/ala.do?isbn=0072965819&alaid=ala_1032810&showSelf StudyTree=true http://www.youtube.com/watch?v=IWMJIMzsEMg

Why is it necessary to have so many different types of cells in the immune system?

Let’s Act It Out!!!

