ECM and Connective Tissue Flashcards
connective tissue
tissue that connects, supports, binds, or separates other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibers, and including cartilaginous, fatty, and elastic tissues.
types of connective tissue
proper or specialized
proper CT
loose or dense
specialized CT
bone, blood, cartilage
loose CT
areolar, adipose, or reticular
dense CT
regular, elastic, or irregular
bone CT
spongy or compact
cartilage CT
elastic, hyaline, or fibrocartilage
Resident CT
Live in that particular area;
fibroblasts (chondroblasts, osteoblasts, odontoblasts) or adipocytes
Type 1 collagen
fibers; skin, bone, ubiquitous
Type II collagen
network of fibrils; hyaline cartilage, elastic cartilage
Type III collagen
fibers; reticular fibers
not present in h&e staining- have to do silver stain in order to visualize
during remodeling they are the first type of collagen to be laid down
type 4 collagen
network (no fibers); basement membranes
assembly of type 1 collagen
1) 3 precursor alpha chains assemble and become procollagen (triple helix with loose ends)
2) procollagen peptidase cleaves and it becomes collagen molecule (insoluble and occurs in extracellular domain)
3) assembly–> collagen fibril
4) assembly–> collagen fiber
LOX
lysyl oxidase
oxidizes primary amines on collagen and elastin substrates to reactive semialdehydes that condense to form covalent cross-linkages to make collagen fibrils
tendon
attaches to muscle at one end and bone or skin at the other end; transfers mechanical energy from muscle;
consists of dense regular connective tissue composed of primarily type 1 collagen
skin
dense, irregular connective tissue; type 1 collagen
epithelial lining CT
loose connective tissue supports epithelial linings of GI, GU, and respiratory tracts and is found as packing tissue in many organs
space between type 1 collagen filled with ground substance
ground substance
gel like amorphous material; composed of large proteoglycans, glycosaminoglycans, glycoproteins, and WATER; growth factors are pround and presented to cells
reticular fibers
supporting framework for highly cellular organs such as spleen and liver and lymph nodes,
type 3 collagen;
only seen under silver staining;
commonly in places where cells are loosely held together and cells are coming in and moving out
composition of elastic fibers
tropoelastin, fibrillin I and II, microfibril associated glycoprotein (MAGP)
also assembled in extracellular environment;
flexible fibers due to cross-linking
can be present as fibers or sheets
synthesis of elastic fibers
1) rough ER–> synthesis of proelastin (desmosine and isodesmosine), MAGP, and fibrillin 1 and 2
2) golgi apparatus–> packaging and secretion of protein
3) extracellular space–> coassembly of MAGP and tropoelastin to produce immature elastic fibers; fibrillin 1- force bearing structural support; fibrillin 2- regulates assembly of elastic fiber
LOX does linking here as well
Defect in elastic fibers
Marfan’s syndrome (abraham lincoln)- aorta