Defending Infection

Homework Due Thursday

Complete 35.2 Worksheet

PathogensNAME CHARACTERISTIC DISEASESViruses 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 diseasesDifferent for different diseases

SneezingCoughingPhysical contactExchange of body fluidsInfected animals

Droplets in the air/doorknobsWASH YOUR HANDS!

Symbionts vs. Pathogens

Symbionts are harmless to the bodySometimes 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 hostRelease poisons that kill host cellsWorms might block blood flow or take nutrients

First Line of DefenseDead cells!Skin make penetration of pathogens very difficultActs as “armor” to defend the bodyHoles in your “armor” include:

MouthEyesNose

First Line of DefenseSaliva, mucus and tears contain lysozyme

Enzymes that breaks down bacterial cell walls

Mucus traps pathogens in nose and throatCilia push the trapped pathogens to the stomach where they are swallowed.

Inflammatory ResponseInfected areas become red and painfulPathogens stimulate cells to release histamines

Increase blood flow and nutrient fluids

Swelling occurs when fluids leak from expanded blood vesselsHow does this compare to sprained ankle? Or a broken finger?

Inflammatory ResponseWhite blood cells move into infected tissues

Phagocytes are WBCs that engulf (eat) and destroy bacteria

Interferons? Interfere with the growth of virusesDon’t allow synthesis of viral cells

FeverSlows pathogens and speeds up immune system

Immune SystemBasis is to differentiate between domestic and foreign Domestic signals notify the Immune System they are good for the bodyForeign objects are unable to replicate passwordRecognizing “self” is vital to the success of the Immune System

Immune SystemMust 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 SystemAntigens are foreign substances that trigger the immune systemAntibodies are created to “tag” specific antigens to be destroyed by phagocytes

Homework Due Thursday

Complete 35.2 Worksheet