Histology (connective tissue, cartilage and bone) Flashcards
What is the primary function of connective tissue?
To provide the structural support and connecting framework for all the other tissues of the body
What is the main constituent of connective tissues?
fibers and extracellular matrix (ECM)
What is extracellular matrix?
sound substance- represents a combination of collagens, noncollagenous glycoproteins, and proteoglycans surrounding the cells of connective tissue
What is the resident cell of connective tissue?
fibroblast
What is the fibroblast responsible for?
production and maintenance of the ECM
What are the immigrant cells of connective tissue?
macrophages, mast cells, and plasma cells
What are the important roles of connective tissue?
immune and inflammatory responses and tissue repair after injury.
What does loose connective tissue contain and where is it normally found?
contains more cells than collagen fibers.
generally found surrounding blood vessels, nerves, and muscles
What does dense connective tissue contain?
more collagen fibers than cells
What are the 2 subsets of dense connective tissue
regular and irregular
What is dense regular connective tissue?
when collagen fibers are preferentially oriented as in tendons, ligaments, and the cornea
What is dense irregular connective tissue?
collagen fibers are randomly oriented as in the dermis of the skin and wall of the intestine
What has an impact of the healing time of regular dense connective tissue?
it is generally poorly vascularized
What are the 4 main components of the ECM?
glycosaminoglycans, proteoglycans, adhesive glycoproteins, and collagen
What are glycosaminoglycans (GAGs)
long unbranched polysaccharides consisting of repeating disaccharide units.
What molecules are highly negatively charged and associate with large amounts of water to create hydrated gels with high viscosity and low compressibility?
Glycosaminoglycans (GAGs)
What are the specific GAGs of physiological significance?
hyaluronic acid, dermatan sulfate, chondroitin sulfate, heparin, heparin sulfate, and keratin sulfate
What are proteoglycans?
family of macromolecules composed of a protein core to which at least one glycosaminoglycan is covalently bound.
What is the most simple proteoglycan?
Decorin consists of a core protein and a single glycosaminoglycan.
What is a more complex proteoglycan?
aggrecan, found in articular cartilage and consist of a core protein with many bound glycosaminoglycans
What highly negatively charged molecules range in size from 50,000 Da to 3,000,000 Da?
proteoglycan
What molecules help to organize and stabilize the matrix by interaction with the molecules (i.e collagen)?
proteoglycan
What are proteoglycans a component of?
component of the basal lamina of epithelial cells and because of their negative charge create a barrier to the passage of positively charged molecules from the epithelium into other cells or connective tissues.
What are adhesive glycoproteins a component of?
ECM of some tissues
What is the function fo adhesive glycoproteins?
they help to facilitate the attachment of cells to the ECM and are also involved in affecting the growth, survival, morphology differentiation and motility of cells.
What are 2 well known examples of ECM glycoproteins ?
modular protein laminin and fibronectin
What do adhesive glycoproteins consist of?
disulfide-bonded subunits with binding sites for cells and other components of the ECM
What are the most abundant types of collagen?
Type I, Type II, Type III
What do Type I, Type II, Type III collagen form?
They form fibril of similar structure that provide tensile strength to tissues
How is the collagen molecule formed?
3 collagen Alph-chains associate in a characteristic right-handed helix
What characteristic amino acid sequence does each Alph-chain of collagen have?
every third amino acid is glycine, that allows for the proper formation of the title helix.
What are the higher-order structures that individual collagen molecules associated together to form?
collagen fibers
What is cartilage?
a specialized type pot connective tissue that consists of cells (chondrocytes) embedded in ECM
In most cases what is cartilage surrounded by?
fibrous connective tissue layer called the perichondrium
What does the perichondrium consist of?
an outer fibrous layer and an inner chondrogenic layer that contains stem cells that differentiate into new chondroblasts and chondrocytes.