Connective Tissue Flashcards
Connective tissue is different from epithelium in that it has ___ cells and ___ amounts of extracellular matrix
few; large
What is the most important function of connective tissue?
structural support
Connective tissues are used for storage of ____
metabolites
True or false?
Connective tissues play an important role in defense and protection by mediating immune responses, as well as in repair by formation of fibrous scars.
true
What are the three main types of fibers present in connective tissue? What are they formed by?
collagen fibers: collagen
reticular fibers: collagen
elastic fibers: elastin and fibrillin
True or false?
Collagen is the most abundant protein in the human body
true
What produces collagen?
fibroblasts
Collagen fibrils are formed by polymerized ____ molecules
tropocollagen
Tropocollagen is formed by a ___ of collagen molecules
trimer
True or false?
Collagen fibrils can be visualized in the light microscope
false; only collagen fibers and reticular fibers can be visualized in the light microscope
Collagen fibrils are assembled into collagen fibers, which are then assembled into collagen ___
bundles
note: collagen bundles are formed only by type I collagen
Where is type I collagen found?
dermis, tendons, ligaments, fascia, bone
Where it type II collagen found?
cartilage
note: this type of collagen forms fibrils but not fibers
Where is type III collagen found?
forms banded fibrils that assemble into reticular fibers which form a supporting framework for loose connective tissue, walls of blood vessels, lymphoid tissues, bone marrow, smooth muscle, nerves, lungs
Where is type IV collagen found?
basal lamina
What is the name of the syndrome caused by defective collagen fibers. Typically patients present with skin, hyper elasticity, loose, unstable joints, low muscle tone, bone abnormalities
Ehlers-Danlos Syndrome
Elastin is a protein that contains a ___ domain, which causes the elastin molecules to coil in aqueous environment
hydrophobic
Elastin molecules are cross-linked by covalent bonds. True or false?
true
_____ is a glycoprotein that forms thin microfibrils that surround the developing elastic fibers and provide substrate for their assembly
fibrillin
Mutations in the fibrillin gene cause a congenital connective tissue disorder called the ____ syndrome, which results in cardiovascular, skeletal, and ocular defects including mitral valve prolapse, rupture of elastic arteries, etc.
Marfan’s
___ ____ fills in spaces between the fibers in the extracellular matrix
ground substance
What are the main components of ground substance?
glucosaminoglycans (GAGs), proteoglycans, and multiadhesive glycoproteins
Which is the most abundant component of ground substance?
GAGs
The strong negative charge of GAGs make them hydrophilic. Explain the importance of this
GAGs bind water and form a highly hydrated gel - helps resist compression and deformation and allows quick diffusion of water-soluble particles
True or false? Hyaluronic acid is never present in the extracellular matrix.
false; always present
True or false? Hyaluronic acid does not form proteoglycans.
true
Describe the structure of a proteoglycan
Proteoglycans are composed of GAGs covalently attached to core proteins. The proteoglycans attach noncovalently though a link protein to long chains of hyaluronic acid and form giant aggregates.
What do multi adhesive glycoproteins do?
serve as cross-links between collagen, extracellular matrix, and cells and play an important role in stabilizing the ECM
Multiadhesive glycoproteins bind ECM to the transmembrane proteins form the ___ family, which are associated with hemidesmosomes and focal adhesions
integrin
What is the most abundant glycoprotein in the connective tissue?
fibronectin
note: each fibronectin molecule is a dimer
This multiadhesive glycoprotein is present in the basal lamina
laminin
Resident cells of the connective tissue undergo mitosis ____ the connective tissue and spend most of their lifetime ___ the connective tissue
within; in
What is the principal resident cell of connective tissue?
fibroblasts
What do fibroblasts do?
produce components of the ECM, including collagen and elastic fibers, GAGs, proteoglycans, multi adhesive glycoproteins, and others
____ fibroblasts are present in the actively growing connective tissue, or during wound repair. They are characterized by abundant cytoplasm with many thin processes. The nucleus is oval-shaped, pale, euchromatic, usually with one or more well-expressed nucleoli. They are commonly found in loose connective tissue.
active