chpater 5 Junqueira's summary

Chapter 5:

 Connective tissues are mainly ECM
 Originate from embryonic mesenchyme (middle layer of embryo…mesoderm)
 Cells of connective tissue:
o Fibroblasts:
 Most common
 Produce and maintain most of the tissue’s EC components.
 Synthesize and secrete collagen and elastin
 Active fibroblast has more branched cytoplasm, large nucleus, and prominent
nucleolus.
 Myofibroblasts have a contractile function and are enriched with a form of
actin.
o Adipocytes:
 They are fat cells
 Storage of lipids as neutral fats
o Macrophages and mononuclear phagocyte system:
 Macrophages are derived from monocytes.
o Mast Cells:
 Cytoplasm filled with basophilic secretory granules
 Granules display metachromasia (change color of some dyes)
 The secretory granules of such cells release:
 Heparin: anticoagulant
 Histamine: increase vascular permeability and smooth muscle
contraction
 Serine proteases: activate carious mediators of inflammation
 Eosinophil
 Cytkokines: directs activities of leukocytes
 Phospholipid
 Originate from progenitor cells in bone marrow
 Promotes allergic reactions (immediate hypersensitivity reactions)
o Plasma cells:
 B-lymphocyte-derived antibody-producing cells
 Basophilic cytoplasm dued to RER,
o Leukocytes:
 Diapedesis: process by which they travel between endothelial cell lining to reach
connective tissue.
 Increases during inflammation
 Fibers:
o Collagen:
 Resistant
 Most abundant protein in human body
 3 main functions:
 Fibrillar collagens: