Immune System Unit 9 Miss Wheeler

Introduction � The immune system works to protect the body

from foreign invaders (bacteria, viruses, toxins, etc.)

Immune System � Defends against harmful organisms, chemicals, etc. � 2 types of defense:

�  Nonspecific- 1st and 2nd line of defense �  Specific- 3rd line of defense

Nonspecific- 1st Line of Defense � EXTERNAL BARRIERS � Skin/Hair- epidermis creates physical barrier � Sweat, Mucous, Saliva- creates chemical barrier to

try to destroy pathogens

Nonspecific- 2nd Line of Defense �  INTERNAL BARRIERS � Phagocytes- “eats” and breaks down foreign

particles (ex. Neutrophil) � Natural Killer Cells- destroy cells with foreign antigen

markers �  Inflammatory Response- response to injured body

tissue

Phagocytes- 2nd Line

Natural Killer Cells- 2nd Line

Inflammation- 2nd Line

� 5 SIGNS 1.  Redness 2.  Swelling 3.  Heat 4.  Pain 5.  Fever

� Histamine- dilates and increases permeability of blood vessels

Inflammation- 2nd Line

Specific- 3rd Line of Defense � Lymphocytes- White blood cells called T-cells and

B-cells; recognize and respond to antigens � “Acquired Immunity”- many lymphocytes will have

a permanent defense against a specific pathogen once it has been introduced to it once.

Lymphocytes- 3rd Line

� T-cells: �  Killer- scan surface of cells and

destroys foreign cells �  Helper- signal B-cells to produce

antibodies; get help from phagocytes

� B-cells: �  Produce antibodies that

agglutinate cells with foreign antigens

Vaccines �  Imitate an infection, resulting

in acquired immunity to a specific pathogen

� Trigger immune response that produces T-cells and generates antibodies (made by B-cell)

� Many “memory” T and B cells will protect against that specific pathogen if exposed to it in the future.

Vaccines