Cellular response
- Blood flow through capillaries in area of inflammation slows as fluid is lost and viscosity increases
- Neutrophils and monocytes move to inner surface of capillaries and then migrate through capillary wall to site of injury
- Chemotaxis
- Directional migration of WBCs along concentration gradient of chemotactic factors
- Mechanism for accumulating neutrophils and monocytes at site of injury
- Neutrophils
- First leukocytes to arrive at site of injury (6 – 12 hours)
- Phagocytize bacteria, other foreign material, and damaged cells
- Short life span (24 – 48 hours)
- Pus is composed of
- Dead neutrophils accumulated at site of injury
- Digested bacteria
- Other cell debris
- Bone marrow releases more neutrophils in response to infection, resulting in elevated WBC
- Monocytes
- Second type of phagocytic cells to migrate to site of injury from circulating blood
- Attracted to the site by chemotactic factors
- Arrive within 3 to 7 days after onset of inflammation
- On entering tissue spaces, monocytes transform into macrophages
- Assist in phagocytosis of inflammatory debris
- Macrophages have a long life span and can multiply
- Macrophages
- Important in cleaning area before healing can occur
- May stay in damaged tissues for weeks
- Cells may fuse to form multinucleated giant cell
- Lymphocytes
- Arrive later at the site of injury
- Primary roles of lymphocytes involve
- Cell-mediated immunity
- Humoral immunity
- Chemotaxis
