Flashcards in Histology: Connective tissue (lecture) Deck (63)
What type of connnective tissue surrounds vessels and nerves?
loose CT (acts to fill and pack around)
T or F: dense CT has thinner fibers than loose CT?
What type of connective tissue is characterized by loose packing of its fibers?
What type of CT has large, closely packed fibers and contains cells that are mostly fibroblasts?
What are 4 areas where dense irregular CT can be found?
Stroma of organs
dermis of skin
periosteum and perichondrium
capsules of organs
What are 3 areas where dense regular CT can be found?
What does dense regular CT consist of?
fibroblasts in linear rows and paralel-oriented collagen fibers
What type of collagen is typically found in dense regular CT?
type I - resisted tensile stress
Where can reticular connective tissue be found? (5 places)
T or F: reticular cells are modified fibroblasts?
What type of collagen makes up reticular fibers?
type III collagen
What allow special stains to be used in reticular fiber visualization?
Lots of carbohydrates
Compare reticular cells to fibroblasts
they are branching and have much more cytoplasm (they lie along the length of the reticular fiber)
What type of cells and fibers are most important in lymph nodes and blood forming organs?
What is the earliest CT in the embryo?
mesenchyme - undifferntiated and can form all kinds of CT
T or F: mesenchyme contains sparse reticular fibers in an abundant ground substance?
T or F: Mesenchymal cells are non-existent in adulthood
False - they are more common in children but a smaller amount persist into adulthood
What is a pericyte?
adult mesenchymal cell that can give rise to fibrolasts and participate in new vessel formation during wound healing
How does CT participate in tissue repair in the body most often?
fibroblasts become myofibroblasts and mesenchymal stem cells
Describe what scar tissue is.
dense irregular CT that may compromise function (e.g. cornea)
What are myofibroblasts derived from?
What cells are partly responsible for wound contraction?
T or F: myofibroblasts are intermediates between fibroblasts and smooth muscle because they contain actin.
How do myofibroblasts work?
They have proteins attached to collagen outside of cell and actin in the cell. The proteins move along actin and grip onto collagen to pull cells together
What happens as a clot forms in the skin?
macrophages and neutophils invade and clean up debris, dead cells, degrade ECM and collagen
What are growth factors in the wound produced by?
What do growth factors in the wound stimulate?
fibroblasts and mesenchymal stem cells proliferate and re-synthesize ECM (sometimes scar = hyperprolferative)
T or F: collagen metabolism is low in adults
True - degration and deposition = usually equal
In what adult tissue is collagen metabolized at a higher rate?