The Immune System

• The First Lines of Defense:– Skin– Antimicrobial proteins– Cilia– Gastric Juice– Symbiotic bacteria – your ‘microbiome’

This is directly from the Cliffs book . . .so make sure you read that

• Second Line of Defense– Phagocytes– Complement – promote cell lysis– Interferons - ‘interfere’ with viral reproduction– Inflammatory response• Histamine• Vasodilation• Phagocytes• Complement

Immune Response

• The Third Line of Defense:– This targets specific antigens – any molecule that

can be identified as foreign

Major Histocompatibility Complex

• The MHC allows the immune system to differentiate between self and non-self cells.

- Made up of glycoproteins- Found on the membranes of all body cells - 20 genes code for these; unlikely that

two people have the same set

Lymphocytes!

• Primary Agent of the Immune Response– B Cells – originate and mature in the Bone Marrow – Respond to antigens through antigen receptors

called antibodies• Y shaped proteins, 5 different classes

5 Classes of Antibodies

T cells• Lymphocytes that originate in the bone marrow

but mature in the thymus gland

– Have antigen receptors, but they are not antibodies

– You should read up on the additional information . . .

Responses of the Immune System-1.CELL MEDICATED2.HUMORAL

• Cell-mediated response– Uses T cells to respond to any non self cell,

including cells invaded by pathogens.

Cell Mediated Response

The Humeral Response

• Involves most cells and responds to antigens or pathogens

- B cells produce plasma cells- B cells produce memory cells- Macrophage and helper T cells

stimulate the production of additional B cells

Why aren’t we dead?

• 1. Antibodies

• 2. Vaccines

• 3. Passive Immunity – placenta, breast milk