Defending Infection

Homework Due Thursday

Complete 35.2 Worksheet

PathogensNAME 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 diseasesDifferent for different diseases

Sneezing

Coughing

Physical contact

Exchange of body fluids

Infected 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 problemsDestroy 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 lysozymeEnzymes 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

FeverSlows 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 invaderImmune 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