Download What Cause Diseases?

What Cause Diseases?
Chapter 18
What is a disease?
A disease is a condition that
affects the proper
functioning of the body or
mind.
2 Types of diseases
 Communicable
– Diseases that can spread.
 Example:
the common cold
 Noncommunicable
– Diseases that do not spread
 Example:
Cancer and Diabetes
Where do communicable
disease come from?
Simply GERMS
(aka Pathogens)
4 Classes of Pathogens
1.
Viruses
2.
Bacteria
3.
Protozoa
4.
Fungi
How are these germs
spread?
Examples
Direct contact (shaking hands)
 Indirect contact (sneezing, coughing)
 Eating or drinking contaminated food or
liquid (sharing a drink/food)
 Contact with animals or insects (bites)


Important terminology:
– Contagious- A disease that can be spread
to others by direct or indirect contact.

Does washing your hands really work???
What types of defenses does
our body have?
How our body plays defense
 Skin
 Body
(our 1st line of defense)
Fluids (saliva, tears, etc.)
 Mucous
Membranes- Tissues that line
the inside of your mouth, throat, and
nose.
– Coated with a sticky fluid called mucous
which traps and destroys germs
If those don’t work…
 The
Immune System
– A group of cells, tissues, and organs
that fight disease
 Important
parts:
– Lymphocytes: white blood cells that
attack harmful germs
– Antibodies: chemicals produced by
lymphocytes to fight specific germs or
diseases.
What about a vaccine?
 Dead
or weakened germs introduced
into your body.
– Why?
 This
causes the immune system to
make antibodies to fight a specific
pathogen