1. Lesson 5
How do systems keep
the body healthy

2. Immune System
• Your body must constantly defend itself
against organisms that are trying to attack it..
• These organisms are called PATHOGENS
• Pathogens: bacteria, viruses and fungi that
cause disease.
• Enter the body through its openings.

3. Body First Line of Defense
• Skin: effective barrier
• Tears: wash pathogens
away contain chemicals
that kill them
• Nose, Throat and
Mouth: contain mucus
that traps pathogens
• Stomach: juices contain
pathogen killing
pathogens

4. Reflexes
• Sneezing and
Coughing: rid lungs
and throat of
pathogens.
• Stomach: expels
food that contains
pathogens

5. Immune Systems
• When first defenses don’t
work Immune system kicks
in.
• Increases blood flow to
area of pathogens
• White blood cells produce
antibodies
• Antibodies: chemicals
that kill specific
pathogens
• Vaccine is another way to
trigger your immune
system to produce white
blood cells to fight
pathogens

6. Systems Work Together
• Respiratory and circulatory- Work together
during activities
• Endocrine systems- maintain stability
• Digestive system- prepares body for activity
• Nervous system- gather info about the
environment
• Muscular and skeletal- work together for
movement