grade 11 immune system slide

2. INTRODUCTION TO IMMUNITY
•AN IMMUNE SYSTEM IS A SYSTEM OF
• BIOLOGICAL STRUCTURES AND
•PROCESSES WITHIN AN ORGANISM
•THAT PROTECTS AGAINST DISEASE.
•IN ORDER TO FUNCTION PROPERLY, AN IMMUNE SYSTEM MUST DETECT A
WIDE VARIETY OF AGENTS, FROM VIRUSES TO PARASITIC WORMS, AND
DISTINGUISH THEM FROM THE ORGANISM'S OWN HEALTHY TISSUE.

3. COUNTER ACTION OF THESE AGENTS
•THESE AGENTS ARE REFERRED TO AS PATHOGENS – AN ORGANISM OR
SUBSTANCE THAT COULD CAUSE A DISEASE.
•PATHOGENS CAN RAPIDLY EVOLVE AND ADAPT TO AVOID DETECTION AND
DESTRUCTION BY THE IMMUNE SYSTEM.
•AS A RESULT, MULTIPLE DEFENCE MECHANISMS HAVE ALSO EVOLVED TO
RECOGNIZE AND NEUTRALIZE PATHOGENS.

4. COUNTER ACTION OF THESE AGENTS
•PHYSICAL BARRIERS PREVENT PATHOGENS SUCH AS BACTERIA
AND VIRUSES FROM ENTERING THE ORGANISM.
•IF A PATHOGEN BREACHES THESE BARRIERS, THE INNATE IMMUNE
SYSTEM PROVIDES AN IMMEDIATE, BUT NON-SPECIFIC
RESPONSE.
•INNATE IMMUNE SYSTEMS ARE FOUND IN ALL PLANTS AND
ANIMALS

5. COUNTER ACTION OF THESE AGENTS
• IF PATHOGENS SUCCESSFULLY EVADE THE INNATE RESPONSE, VERTEBRATES POSSESS A SECOND LAYER OF
PROTECTION, THE ACQUIRED IMMUNE SYSTEM,
• WHICH IS ACTIVATED BY THE INNATE RESPONSE.
• HERE, THE IMMUNE SYSTEM ADAPTS ITS RESPONSE DURING AN INFECTION TO IMPROVE ITS RECOGNITION OF THE
PATHOGEN.
• THIS IMPROVED RESPONSE IS THEN RETAINED AFTER THE PATHOGEN HAS BEEN ELIMINATED, IN THE FORM OF AN
IMMUNOLOGICAL MEMORY,
• AND ALLOWS THE ACQUIRED IMMUNE SYSTEM TO MOUNT FASTER AND STRONGER ATTACKS EACH TIME THIS
PATHOGEN IS ENCOUNTERED

6. DIFFERENCES IN THE COMPONENTS OF THE
IMMUNE SYSTEM
IInnate immune system Acquired immune system
Response is non-specific Pathogen and antigen specific response
Exposure leads to immediate maximal response Lag time between exposure and maximal response
Cell-mediated and humoral components Cell-mediated and humoral components
No immunological memory Exposure leads to immunological memory
Found in nearly all forms of life Found only in jawed vertebrates

7. 2. INNATE IMMUNITY
• INNATE IMMUNE RESPONSES ARE ACTIVE IMMEDIATELY UPON INFECTION AND ARE THE SAME WHETHER
OR NOT THE PATHOGEN HAS BEEN ENCOUNTERED PREVIOUSLY.
• IT INCLUDES BARRIER DEFENCES
• AND INTERNAL DEFENCES

8. BARRIER DEFENSE SYSTEM
•INCLUDES:
• THE SKIN
•MUCUS MEMBRANES OF DIGESTIVE-, RESPIRATORY- URINARY AND REPRODUCTIVE
• TRACT
•BODY SECRETIONS: MUCUS, SALIVA (LYSOZYMES), TEARS, OIL GLAND SECRETIONS,
ACID IN STOMACH, SWEAT.

9. MUCUS MEMBRANES
•SOME CELLS IN MUCUS MEMBRANE PRODUCE MUCUS.
•MUCUS IS A VISCOUS FLUID THAT ENHANCES DEFENCES –
TRAPPING MICROBES AND OTHER FOREIGN PARTICLES

10. IN THE TRACHEA, CILIATED EPITHELIAL
CELLS SWEEP MUCUS AND THE TRAPPED
MICROBES UPWARDS, HELPING TO
PREVENT INFECTION OF THE LUNGS

11. MUCUS MEMBRANE
• BODY SECRETIONS CREATE AN ENVIRONMENT THAT IN UNFAVOURABLE FOR MICROBES.
• LYSOZYMES IN SALIVA, MUCOUS SECRETIONS, AND TEARS DESTROY SUSCEPTIBLE BACTERIA AS THEY
ENTER THE RESPIRATORY TRACT OR OPENINGS AROUND EYES.
• ACID IN STOMACH KILL BACTERIA
• OILS AND SWEAT GIVE HUMAN SKIN A PH BETWEEN 3-5, WHICH IS ACIDIC ENOUGH TO PREVENT THE
GROWTH OF MICROORGANISMS.

12. INTERNAL DEFENSE
• IF THE BARRIER DEFENCES ARE DAMAGED AND PATHOGENS DO ENTER THE BODY OF AN ORGANISM, A
SECOND LINE OF DEFENCE WILL BE ACTIVATED.
• THIS DEFENCE SYSTEM IS THE INTERNAL DEFENCE SYSTEM AND IS MORE SENSITIVE AND INCLUDES:
PHAGOCYTOSIS AND INFLAMMATION

13. PHAGOCYTOSIS
• PROCESS BY WHICH CERTAIN LIVING CELLS CALLED PHAGOCYTES INGEST OR ENGULF OTHER
CELLS OR PARTICLES.
• THE PHAGOCYTE MAY BE A ONE-CELLED ORGANISM, SUCH AS AN AMOEBA, OR ONE OF THE BODY
CELLS, SUCH AS A LEUKOCYTE (WHITE BLOOD CELL).
• IN HIGHER ANIMALS PHAGOCYTOSIS IS CHIEFLY A DEFENSIVE REACTION AGAINST INFECTION
AND INVASION OF THE BODY

14. DIFFERENT TYPES OF PHAGOCYTIC CELLS:
•NEUTROPHILS ENGULF AND DESTROY MICROBES
•MACROPHAGES ARE PART OF THE LYMPHATIC SYSTEM AND ARE FOUND THROUGHOUT
THE BODY
•EOSINOPHILS DISCHARGE DESTRUCTIVE ENZYMES
•DENDRITIC CELLS STIMULATE DEVELOPMENT OF ACQUIRED IMMUNITY

15. NEUTROPHIL

16. MACROPHAGE

17. EOSINOPHIL

18. DENDRITIC CELL