Connective Tissues Flashcards
Where is the primitive connective tissue derived??
Mesodermal mesencchyme
What is the function of a fibroblast?
They synthesize and maintain proteinaceous ground substance and connective tissue fibers. (Collagen, Elastin, and reticular fibers).
Where are reticular cells located? And What do they produce?
They are located in the lymph nodes and the bone marrow. They synthesize reticular fibers from reticulin.
What is the principle fiber in the extra cellular matrix?
Collagen because it is know for its tensile strength.
What type of collagen is most abundant in the body?
Type one collagen
Where is the type V collagen found?
Cornea, placenta, dermatology-epidermal junctions.
What is the best known collagenopathy?
Ehlers-Danlos syndrome. Affects type V collagen characterized by hyper extension of joints, skin fragility and poor wound healing.
How is collagen formed?
Starts as pro-collagen—> secretory vessels and secreted into the ECS—> Enzymatic modification in the extra cellular region—> this forms troop collagen—> polymerization—> collagen microfibrils—> collagen bundle.
How are elastic fibers formed?
Formed by fibroblasts as tropoelastin. This then polymerizes in the ECM to become elastin!
What are the two components of elastic fibers?
Elastin and Fibrillin
Elastin is the protein core and fibrillin is the structural glycoprotein.
What are fibrillin and fibronectin?
They are structural glycoproteins.
Where is fibronectin found?
In the basement membrane. This anchors the cell membrane to the extra cellular matrix. Through integrins.
What are the non-filamentous molecules of the connective tissues?
Laminin- sulfates glycoproteins this is a major component of the basement membrane. It is produced by epithelial cells and endothelial cells.
Entactin- sulfates gylcoprotein binds with laminin
Tenascin- binds the cells to extracellular matrix; thought to be important in cell migration in developing nervous system.
describe the ground substance and what sugar is most abundant in the ground substance?
It is an amphorous, transparent material with properties of similar-fluid gel.
The sugar is almost always and amino sugar (n-acetyl glucosamine or galactosamine.
Most GAG’s covalently bind to protein molecules to form what?
Proteoglycans
Types of GAG’s
Hyaluronic acid Chondroitin sulfate Keratin sulfate Dermatan sulfate Heparin sulfate
Hyaluronic acid
Found in most connective tissue
Chondroitin sulfate
Found in cartilage, bone, cornea, and intervertebral disk
Keratan sulfate
Found in cartilage, bone, cornea, and intervertbral disk
Dermatan sulfate
Found in dermis of the skin, blood vessels, and heart valves.
Heparin sulfate
Found in the basement membrane, lung, and liver.
What is the main components of ground substance?
Gag’s (1’ hyaluronic acid), proteogylcans, an water.
Hyaluronic Acid (Hyaluronate)
The predominant GAG in loose connective tissue. It lacks sulfates side groups, thousands of sugars long, doesn’t form a proteoglycan, but will connect to them.
What is the function of hyaluronidase?
Pathogenic bacteria produce this to break through the ground substance layer and facilitate their spread.
Loose connective tissue
Sparse fibers and abundant ground substance.
Located beneath the epithelia and around the nerves and blood vessels.
Adipocytes are derived from what cells?
Lipoblasts
Where is white fat found in the body?
Dermis, and around the intraperitoneal.
Where is brown fat found in the body?
The adrenals.
Epithelial cells produce what?
Keratin, there are several different types which is proven helpful in tumor ID.
What embryonic levels are epithelial derived from
Endo-
Ecto-
Mesoderm
Epithelial cells rely on diffusion of O2 and nutrients from the underlying tissue.
It’s just a fact of life.
What is another name for the basement membrane?
External lamina.
What are cadherins?
A class of cell adhesion molecules aka integrins. Type of transmembrane glycoproteins.
What are some of the attachment proteins associated with desmosomes aka macula adherins?
Does opal kin’s, desmogleins, and tonofilaments.
Where are hemidesmosomes located? Also what is the protein that anchors it to the basement membrane?
They are located in high abrasion areas (skin).
Integrins.
What are the three separate zones of the junctional complex aka the terminal bar
Zonula occludens (tight junction) Zonula adherens (adherent junction) Macula adherens (desmosomes)
What are the names of microvili in the intestine and in the renal tubules?
Striated Border = intestines
Brush border = renal tubules.
What are the two strokes the cilia make?
Effective stroke:
rapid and rigid
Recovery Stroke:
Slower and flexible
Metachronal rhythm
The synchronous beat of cilia
What do cillia normally contain?
Microtubule doublets with a dynein arm.
What glands contain myoepithelial cells?
Exocrine glands
Merocrine glands excrete mostly what product?
Proteins, through simple exocytosis.
What do apocrine glands mostly secrete?
Typically lipids. Lose some portion of the cell membrane.
Sweat and mammary glands.
What is an example of holocrine glands?
Sebaceous glands
