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

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) B lymphocytes (B cell) T lymphocyte (helper T cell) T lymphocyte (helper T cell) antigen

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 (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 hill.com/classware/ala.do?isbn= &alaid=ala_ &showSelf StudyTree=true The Immune Response Why is it necessary to have so many different types of cells in the immune system?

Let’s Act It Out!!!