Study Set Content:
a local defect, or excavation, of the surface of an organ or tissue that is produced by the sloughing (shedding) of inflamed necrotic tissue
Ulcer
is a response of prolonged duration (weeks or months) in which inflammation, tissue injury, and attempts at repair coexist in varying combinations
Chronic Inflammation
These are infections by microorganisms that are difficult to eradicate, such as mycobacteria and certain viruses, fungi, and parasites.
Persistent Infections
An example of an exogenous agent is
Particulate Silica
is a chronic inflammatory process of the arterial wall induced, at least in part, by excessive production and tissue deposition of endogenous cholesterol and other lipids
Artherosclerosis
chronic inflammation is characterized by the followin:
- Infiltration with mononuclear cells
- tissues destruction
- Attempts at healing
Infiltration with mononuclear cells, which includes
macrophages, lymphocytes and plasma cells
induced by the persistent offending agent or by the inflammatory cells.
Tissue destruction
Attempts at healing by connective tissue replacement of damaged tissue, accomplished by this process; proliferation of small vessels
Angiogenesis
The dominant cells in most chronic inflammatory reactions are
Macrophages
Derived from hematopoietic stem cells in the bone marrow in postnatal life
Macrophages
Circulating cells of this lineage are known as
Monocytes
In addition, macrophages are present in specific locations in organs where they are specifically called:
liver -
spleen and lymph nodes -
central nervous systems -
lungs -
liver - Kupffer cells
spleen and lymph nodes - sinus histiocytes
central nervous systems - microglial cells
lungs - alveolar macrophages
What are the two major pathways of macrophage activation?
Classical macrophage activation & Alternative macrophage activation
may be induced by microbial products such as endotoxin, which engage TLRs and other sensors; by T cell–derived signals, importantly the cytokine IFN-γ, in immune responses
Classical Macrophage Activation
induced by cytokines other than IFN-γ, such as IL-4 and IL-13, produced by T lymphocytes
Alternative Macrophage Activation
often prominent in chronic inflammatory reactions; Generates long-lived memory cells
roles of lymphocytes
These are three subsets of CD4+ T cells that secrete different types of cytokines and
elicit different types of inflammation.
Th1 Cells, Th2 Cells, and Th17
produce the cytokine IFN-γ, which activates macrophages by the classical pathway
Th1 cells
cells secrete IL-4, IL-5, and IL-13, which recruit and activate eosinophils and are responsible for the alternative pathway of macrophage activation.
Th2
