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. Non-specific (Innate) Immunity

3. Specific Immunity

1st Line of DefenseIntegumentary 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

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

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

Lymphatic system

2nd Line of DefenseThe 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

3rd Line of Defense Specific Immunity

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

B lymphocytes

(B cell)

B lymphocytes

(B cell)

T lymphocyte(helper T

cell)

T lymphocyte(helper T

cell)

antigen

3rd 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 (chemicals that can be used on the skin) 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

http://highered.mcgraw-hill.com/classware/ala.do?isbn=0072965819&alaid=ala_1032810&showSelfStudyTree=true

The Immune Response

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

http://www.youtube.com/watch?v=IWMJIMzsEMg

Let’s Act It Out!!!