Immunity: Part II

WBCs

Internal Defenses of Innate Immunity~White Blood Cells~

- If invaders actually get within the body, then your white blood cells (WBCs) begin their attack

- WBCs circulate throughout the blood, using the bloodstream to get from one organ to another.

Video

WBCs

• aka. Leukocytes• Form from generalized stem cells in bone

marrow– Hemocytoblasts (ALL blood cells and platelets

stem from these cells)

• Lack hemoglobin• Defend the body

Phagocytes: 1st Line of Cellular Defense

Microphages – neutrophils & eosinophils

Macrophages – derived from monocytes

Microphages

• Leave the bloodstream and enter peripheral tissues subjected to injury or infection

The monocyte-macrophage system

• aka: the reticuloendothelial system

Macrophages

• Actively phagocytic cells derived from circulating monocytes.

• Almost every tissue in the body shelters macrophages.

Macrophages

• Fixed – resident macrophages in body tissue– Ex: microglia in CNS– Ex: Kupffer cells in and around blood vessels

in the liver

• Free – visiting macrophages in body tissues– Move into and through– Diffuse

• WBCs are responsible for eating foreign particles by engulfing them

• Once engulfed, the phagocyte breaks the foreign particles apart in organelles called ________

~All Phagocytes~

Lysosomes

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Phagocytic Cells

• Phagocytes attach to their prey via surface receptors

– And engulf them, forming a vacuole that fuses with a lysosome

Pseudopodiasurroundmicrobes.

1

Microbesare engulfedinto cell.

2

Vacuolecontainingmicrobesforms.

3

Vacuoleand lysosomefuse.

4

Toxiccompoundsand lysosomalenzymesdestroy microbes.

5

Microbialdebris isreleased byexocytosis.

6

Microbes

MACROPHAGE

Vacuole Lysosomecontainingenzymes

~All Phagocytes~

Diapedesis Chemotaxis

http://www.nature.com/nature/journal/v404/n6774/fig_tab/404135a0_F1.html

http://www.nature.com/nature/journal/v404/n6774/fig_tab/404135a0_F1.html