Connective Tissue Flashcards
CT vs. Epithelium
CT: widely spread, no polarity, vascularized (usually.. not cartilage)
general CT composition
cells + ECM
CT cells
long-term resident or transient resident
principal cell produces ECM components, all other cells do something else NOT produce ECM
Principal long-term resident cell
produces ECM components (ground substance + fibers)
usually fibroblasts
ECM components
- gelatinous ground substance + fibers/fibrils
- both parts produced by principal CT cell
Ground Substance
rich in GAGs and proteoglycans (interact to form proteoglycan aggregates)
secrete multiadhesive glycoproteins (stabilize matrix and aid in cell-connective tissue interactions)
GAG
Glycosaminoglycan
-long chain, linear polysaccharides
GAGs in CT
in ground substance: keratan sulfate, heparan sulfate, condroitin sulfate, and hyaluronic acid (hyaluronan)
- sulfate = negative (basophilic).. attracts sodium ions which attract water to the matrix
- interact with proteins to form proteoglycans
hyaluronic acid in ground substance
- longer and more rigid than other GAGs
- increases the viscosity of ground substance (makes it thicker)
proteoglycans
- linear proteins with glycosaminoglycan (GAG) side chains
- look like a bottle brush
proteglycan aggregate
proteglycan + GAG (hyaluronic acid)
mutiadhesive glycoproteins
- secreted by principal CT
- stabilize ECM and link EXM to the surface of cells
- ex: fibronectin and laminin (attach epithelial cells to basal lamina)
FIbrous component of CT
- proteins secreted from principal CT cells
- proteins assemble into fibrils (TEM), which usually assemble inter fibers (LM)
3 major types of fibers in connective tissue
- collagen
- elastic
- reticular (type III collagen)
constituency of CT
can be solid (bone) , watery (blood), or viscous (cartilage)
role of ground substance vs. fibers
fibers: tensile strength + resiliance
ground substance: diffusion of molecules + access of blood borne cells
fibroblasts (derived from? role in loose CT, function, in LM, in TEM)
derived from mesenchymal cells
PCT in loose CT
produce TYPE I COLLAGEN + ELASTIC FIBERS
in LM: elongated nucleaus, thin cytoplasm, and hard to tell (unless cell is making a lot of collagen)
in TEM: lots of rER (making proteins!), scalloped cell body, and thin processes extending from cell into collagen bundles
Macrophages (derived from? role in loose CT, function, in LM, in TEM)
derived from monocytes
-monocytes in blood, enter loose CT via diapedesis = macrophages
-function: resident phagocytic cells; phagocytosize bacteria or dying cells
in LM: larger nuclei than FB, and indented nuclear envelope, vesicles are apparent (foamy looking) when active
in TEM: lots of lysosomes, extending pseudo pods if active
mast cells
promote inflammation
granules in mast cells and their respective function
heparin (anticoagulant); histamine (promotes inflammation); eosinophil chemotactic factor tryptase (mast cell marker) NO leukotrienes (produced from PM after the release of granules)
uriticaria
hives;
produces from skin mast cell activation
explain inflammation response via mast cell (starting from antibody production) (DEGRANULATION OF MAST CELLS)
- antibody produced by plasma cell and released
- IgE specific receptor on extracellular mast cell bind the antibody to the mast cell
- antibodies bind to antigen (when present)
- ca 2+ channels open (calcium influx)
- granules pour out supstances: heparin (anticoagulant), histamine (promotes inflammation), eosinophilic chemotactic factor
- production of leukotrienes from PM (promotes inflammation)
“promote inflammation” = calls for leukocytes from blood vessel
leukocytes
promote immune response to antigens, parasites, or bacteria (that pass through epithelium)
-include granulocytes and agrangulocytes
cells in CT
- fibroblasts (produce collagen type I + elastic fibers)
- Macrophage (phagocytsize bacteria + old cells)
- Plasma cells (make antibodies)
- Mast cells (promote inflammation)
- adipose (energy storage, convert hormones to estrogen, weight control)
- leukocytes (promote immune response..WBC)