Defending Infection

Homework Due Thursday Complete 35.2 Worksheet

Pathogens NAME CHARACTERISTIC DISEASES Viruses Nonliving, insert genetic material into host cell; take over host cell functions Common cold, flu, chickenpox, warts Bacteria Release toxins that interfere with normal host cell activity Strep throat, anthrax Fungi Infection on surface of skin, mouth, throat Ringworm, thrush Protists Take nutrients from host; inflict damage to cells and tissues Malaria, intestinal diseases Parasites Wormlike; enter through mouth; absorb nutrients through intestinal tract Trichinosis, hookworm, elephantiasis

Spread of diseases Different for different diseases Sneezing Coughing Physical contact Exchange of body fluids Infected animals Droplets in the air/doorknobs WASH YOUR HANDS!

Symbionts vs. Pathogens Symbionts are harmless to the body Sometimes beneficial Bacteria in the Large Intestines help with digestion “Good guys” grow and reproduce without causing problems “Bad guys” cause problems Destroy cells of their host Release poisons that kill host cells Worms might block blood flow or take nutrients

First Line of Defense Dead cells! Skin make penetration of pathogens very difficult Acts as “armor” to defend the body Holes in your “armor” include: Mouth Eyes Nose

First Line of Defense Saliva, mucus and tears contain lysozyme Enzymes that breaks down bacterial cell walls Mucus traps pathogens in nose and throat Cilia push the trapped pathogens to the stomach where they are swallowed.

Inflammatory Response Infected areas become red and painful Pathogens stimulate cells to release histamines Increase blood flow and nutrient fluids Swelling occurs when fluids leak from expanded blood vessels How does this compare to sprained ankle? Or a broken finger?

Inflammatory Response White blood cells move into infected tissues Phagocytes are WBCs that engulf (eat) and destroy bacteria Interferons? Interfere with the growth of viruses Don’t allow synthesis of viral cells Fever Slows pathogens and speeds up immune system

Immune System Basis is to differentiate between domestic and foreign Domestic signals notify the Immune System they are good for the body Foreign objects are unable to replicate password Recognizing “self” is vital to the success of the Immune System

Immune System Must be able to respond to “non-self” Remembers any specific invader Immune system memory allows for the Immune System to respond to it quicker next time Example: Ability to do “Times Tables”

Immune System Antigens are foreign substances that trigger the immune system Antibodies are created to “tag” specific antigens to be destroyed by phagocytes

Homework Due Thursday Complete 35.2 Worksheet