Exam 2: Connective Tissue Flashcards
Function of connective tissue
Structure, defense and protection, nutrition, fat depot for cushioning, insulation, and energy reserves
Fixed cells
Fibroblasts, collagen, myofibroblasts, adipocytes, Mast cells, Macrophages
Migratory cells
Plasma cells, leukocytes,
Active Fibroblasts
Synthesize and secrete fibers and ground substance - basophilic ribosomes, euchromatic nucleus, well developed Golgi body and mitochondria
Typically do not divide but may do so during wound healing
Quiescent Fibroblasts
fibrocyte
Smaller than fibroblast, spindle shaped, fewer processes, cytoplasm is eosinophilic, nucleus elongated and heterochromatic, nucleoli not visible
When stimulated, become active fibroblasts
Hydroxylation of the preprocollagen occurs in the
rER
Is Vitamin C dependent
Assembly of the procollagen molecules (triple helix) occurs in
the rER
Packaging of soluble procollagen in secretory vesicles occurs in
the Golgi body
Cleavage of the nonhelical terminal peptides of procollagen by peptidases occurs in
the extracellular matrix
procollagen aggregates into collagen fibrils
Myofibroblasts
cells that possess characteristics of fibroblasts and smooth muscle cells (actin and myosin present)
More numerous in areas of wound healing
Dupuytren’s contracture
microvascular ischemia leads to trauma to the palmar aponeurosis
Tissue repair causes collagen type I to be replaced by type III, which cross links with myofibroblasts
4th and 5th digits are contracted
Unilocular adipocytes
white adipose tissue
Large cells, closely packed
Contain single lipid droplet not bound by a membrane - inside vimentin filaments
Nucleus pushed to periphery of cytoplasm
Signet ring appearance, thin rim of cytoplasm
Adipocytes secrete
leptin - work to depress appetite
Lipodystrophies
loss of body fat
Absence or defect of normal leptin
leads to morbid obesity
Multilocular adipocyte
brown adipose tissue
smaller than unilocular cells, many mitochondria, multiple fat droplets in cytoplasm, nucleus spherical and not displaced to periphery
Mast cell
Derived from bone marrow stem cells, contains metachromatic membrane bound granules
Mediators of inflammatory responses - histamine causes increased mucus production of nasal mucosa for example
Macrophages
oval nucleus with heterochromatin along nuclear envelope, indented
Well endowed with Golgi complex, rER and lysosome
Phagocytose cellular debris and microorganisms
Giant cells
fused active macrophages, epithelial-like cells
form in times of chronic inflammatory states
Plasma cells
Derived from B lymphocytes
Nucleus displays a clock face appearance - clumps of heterochromatin along periphery
Intensively basophilic
Negative Golgi image visible - vesicles immediately secreted, not stored
Leukocytes
Following inflammation first mainly neutrophils enter tissue, then monocytes enter
Mesenchymal cells
Gel-like ground substance with glycoproteins and GAGs
Reticular fibers
Located in Embryonic intramembranous bone formation
Mucous CT
contains fibroblasts, hyaluronic acid and glycoproteins
collagen fibers (I and III)
Found in umbilical cord and subdermal in embryo
Loose (areolar) CT
Contains abundant hyaluronic acid, GAGs, proteoglycans, and glycoproteins in ground tissue
Collagen, reticular, and elastic fibers
Fibroblast, macrophage, adipose, mast cells
Found immediately deep to epithelium, & surrounding blood vessels
