1. Defending Infection

2. Homework Due Thursday
Complete 35.2 Worksheet

3. 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

4. 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!

5. 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

6. 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

7. 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.

8. 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?

9. 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

10. 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

11. 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”

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

13. Homework Due Thursday
Complete 35.2 Worksheet