the aim it is to understand the importance of an immune system in our body.

1. IMMUNE SYSTEM
ZAMOKUHLE MYENI
LIFE SCIENCES
GRADE 11

2. INTRODUCTION TO IMMUNITY
• Immune system  system of
biological structures + processes within
organism
• protects against disease.
• Organism function properly  immune system
 detect wide variety of agents
• (viruses, parasitic worms)
• distinguish them from own healthy tissue.

3. INNATE IMMUNE SYSTEMS
Cells + proteins  always present & ready to mobilize
 fight microbes at site of infection.
Main components of innate immune system:
1) physical epithelial barriers,
2) phagocytic leukocytes (WBC)
3) dendritic cells,
4) a special type of lymphocyte called a natural killer (NK) cell,
5) circulating plasma proteins.

4.  If pathogens successfully evade innate response  vertebrates
possess second layer of protection
acquired immune system
activated by innate response
 Now immune system adapts its response during infection 
improve its recognition of pathogen.
 Improved response  retained after pathogen eliminated
 immunological memory
 allows acquired immune system to act faster and stronger attacks
each time this pathogen is encountered.

5. Differences in the components of the
immune system

6. BARRIER DEFENSE SYSTEM
Includes:
 the skin
Mucus membranes of digestive-,
respiratory- urinary and reproductive
tract
oBody secretions: mucus, saliva
(lysozymes), tears, oil gland secretions,
acid in stomach, sweat.

7. Different types of phagocytic cells
Neutrophils  engulf and destroy microbes
Macrophages part of the lymphatic system
and are found throughout the body
Eosinophils  discharge destructive enzymes
Dendritic cells  stimulate development of
acquired immunity

8. PHAGOCYTE ENGULFING A BACTGERIUM
CELL

9. IMMUNE
SYSTEM