Connective tissue Flashcards
What are the two major elements of connective tissue?
Cells (Fixed and migratory)
ECM (fibers and ground substance)
What are the functional attributes of CT?
- Structure
- defense and protection
- nutrition
- fat deposition
All of the different types of connective tissue cellsare derived from what type of cells?
Mesenchymal cells which are derived from mesoderm
What are the different type of connective tissue cells?
Chondroblasts ADipocytes Fibroblasts Mesotheliacal cells Endothelial cells Osteoblasts
What are fibroblasts?
Cells that have the machinery for the synthesis and secretion of fibers and ground substance
What are fibrocytes
Inactive fibroblasts
How would one differentiate between active fibroblasts and inactive fibrocytes?
Look at euchromatin vs heterochromatin
Nucleus shape
Also, cellular organelles
What do fibrocytes typically stain?
eosin
When do fibroblasts divide?
may do so during wound healing. Otherwise nto often.
What is the effect of cortisol on fibroblasts?
Decreases activity
When can you appreciate nucleoli in fibroblasts/fibrocytes?
When they are active
Where does the triple helical structure of collagen form in the cell?
rER
What maintains the solubility of procollagen?
Propeptides at either end of the collagen molecule
What are the steps of collagen synthesis?
- mRNA produced and translated
- collagen helicies warp around each other in rER
- procollagen transported to Golgi, where they are further processed
- Released from Golgi/cell in secretory vesicles
What is the enzyme that removes the non-helical propeptides from the procollagen molecule? Where are they found?
Procollagen peptidases found in the Golgi
Why would you want to cleave the propeptide ends from the procollagen molecule?
To make the collagen insoluble
A lack of Vit C as in scurvy, affects what part of collagen synthesis?
hydroxylation of proline and lysine groups
What are myofibroblasts? Where do they become more numerous?
Cells that possess characteristics of fibroblasts and smooth muscle cells
More numerous in areas of wound healing
What proteins are present in myofibroblasts?
Actin and myosin
What is Dupuytren’s contracture?
microvascular ischemia leads in trauma to the palmar aponeurosis. Tissue repair ensues involving fibroblasts and myofibroblasts. Collagen type I replaced by type III. Contracture at the MP joints due to excess deposition of type III collagen and cross links with myofibroblasts. 4th and 5th digits most frequently involved
What are the two types of adiposites?
White and brown
What is the composition of adipocytes?
Large lipid droplet inside a cell–produces signet ring appearance
What is the intermediate filament that projects into the lipid space of adipocytes?
Vimentin
What hormone do adipocytes secrete?
Leptin
Mutations in leptin or receptor leads to what?
Obesity
What are lipodystrophies?
Abnormal distribution of fat on the body
Defects in Lamin A and lamin C lead to what type of lipodystrophies?
Accumulations in the head and neck.
What is the major difference between white and brown adipocytes?
White store single large droplet,
Brown stores many droplets
Why are brown adipocytes eosinophilic?
Have large amount of Mito
Why do brown adipocytes have a large amount of mitochondria?
To produce heat (newborns cannot shiver)
What is the characteristic feature of mast cells?
metachromasia with toludene blue
What do the secretory granules of mast cells contain?
Histamine
Heparin
Hemotoxic factors