Connective TIssue Flashcards
What are characteristics of connective tissue?
few cells, an abundant matrix, varying amounts of protein fibers.
What are functions of connective tissue?
supports other tissues, binds tissues, provides framework, creates body contours and houses special tissues.
What are the 4 types of connective tissue?
elastic, reticular, loose and dense
What are the 4 types of special tissue?
adipose, cartilage bone and hematopoietic
What does loose tissue look like?
both collagen and elastic fibers in a loose, random fashion.
What fibers predominate in dense tissue?
collagen
What fibers predominate in reticular and elastic tissue?
reticular and elastic.
Where is Wharton’s Jelly found?
the umbilical cord
What is Wharton’s jelly composed of?
collagen, elastic fibers and ECM (e.g. glycoproteins and proteoglycans)
Where is loose CT usually found?
beneath epithelial tissues of most organs and blood vessels. It contains mast cells, macrophages and capilaries.
What are fibroblasts?
cells that lay down the matrix.
Where is dense regulat CT found?
in tenons and ligaments. It has thicker bundles of collagen than loose CT.
Why is dense irregular CT so irregular?
There is no specific orientation of collagen bundles.
What does reticular CT contain?
dense irregular connective tissue with a predominance of reticular fibers. It is associated with lymphatic tissue.
What does elastic CT contain?
an abundance of elastic fibers that form discontinous lamellae.
What are the two types of dense irregular connective tissue?
reticular and elastic
What is white fat?
unilocular; it is a single droptlet of oil that fills a cell.
What is brown fat?
cells that contain numerous smaller lipid droplets. They are more abundant in newborns and are used for heating.
What does “blast” mean?
a cell that is forming something; e.g. a fibroblast is a cell that forms and secretes fibers.
What are the most common cells in the connective tissue?
fibrocytes and fibroblasts. They are scattered in a relatively homogenous matrix.
What does the connective tissue matrix consist of?
protein fibers and ground substance; the most common are collagen fibers.
Where is type I collagen, and what is its function?
general CT and bone; tensile strength.
Where is type II collagen, and what is its function?
hyaline and elastic cartilage, tensile stength.
Where is type III collagen, and what is its function?
parenchyma of organs and walls of blood vessels; reticular framework
Where is type IV collagen, and what is its function?
basement membranes; meshwork and scaffolding
What is the prepropeptide?
The peptide that is the first in collagen formation. It has a signal sequence that is cleaved in the ER of a fibroblast.
What is procollagen?
The cleaved peptide sequence that is secreted into the ECM
What ends are cleaved from the procollagen to allow polymerization?
The non-helical ends.
What is the collagen molecule called once its non-helical ends hvae been cleaved?
tropocollagen.
What to tropocollagen monomers form?
staggered arrays.
What is ehlers-danlos syndome?
a syndrome caused by defects in the synthesis of collagen. It can result in hyperextension of joints, etc. and affects the strength.
What are GAGs?
large, negatively charged linear polymers consisting of repeated dissarchardie units. They form most of the amorphous substances of connective tissue.
What do GAGs form?
proteoglycans.
What are the four groups of GAGs?
hyaluronic acid, heparin/heparin sulfate, chondroitin sulfate, kerain sulfate
Where is hyaluronic acid found?
cartilage, skin, synovial fluid; essentially all connective tissues and in Wharton’s jelly. It is also a lubricant in synovial fluids.
Where is heparin/heparin sulfate found?
basement membrane, skin, lung, liver, blood vessels
Where is condroitin sulfate found?
cartilage, bone, skin, blood vessels, heart valves, cornea; it is the most abundant of the sulfated GAGs.
Where is keratan sulfate found?
type I - cornea; type II - cartilage and nucleus pulposus of intervetebral disks.
What are proteoglycans?
secreted products of resident cells, such as fibroblasts, chondroblasts, etc. They stain with hematoxylin because of sulfate groups.
What are glycoproteins?
proteins with one or more heterosaccharide chains containing hexosamine, galactose and other sugars. They are PAS+ and have a high protein content.
What are examples of glycoproteins?
fibronectin, chondronectin and laminin
What is fibronectin?
the major surface protein of fibroblasts; they occur in plasma and alpha granules of platelets. They link cells, collagen and glycosaminoglycans.
What is chondronectin?
isolated from cartilage; it promotes adhesion of mature chondrocytes to collagenous substrates.
What is laminin?
found in basal lamine and involved in attachment ofepithelial cells to the lamina propria. They are noncollagenous glycoprotein.
