MCM Final - Connective Tissue Flashcards
connective tissue fixed cells
from the connective tissue itself
-mesenchymal, fibroblasts, adipose
connective tissue hematogenous cells
derived from bone marrow
-all types of blood cells
Collagen Type I
most prevalent in body (90% of total collagen)
fibril
heterotrimeric
high tensile strength (skin, tedon, bone, dentin, fascia)
Collagen Type II
fibril
homotrimeric
fibril
cartilage, nucleus, pulposus, notochord, vitreous body, cornea
Collagen Type III
fibril
homotrimeric
adds rigidity***
in skin, uterus, blood vessels, reticular fibers, spleen, lymph nodes
Collagen Type IV
globular**
basal lamina of epithelial cells, kidney glomeruli, lens capsule
homotrimeric
Collagen Type VII
homotrimeric
small fibers
anchoring fibrils in basal lamina
Biosynthesis of Collagen
secreted as procollagen
procollagen has capped ends that must be lysed
in Collagen Type I - procollagen is triple helix with:
two alpha-1 chains and one alpha-2 chains
Periodicity
staggered orientation of procollagen in collagen fibril
provide strength bc of extensive overlapping
collagen fibril have hole zone and overlap zone
Reticular Fibers
collagen type III fibers
add rigidity
found in skin, uterus, blood vessels, reticular fibers, spleen, and lymph nodes
Elastic Fibers
- composition? - example?
composed of:
elastin- globular protein, rich in glycine and proline
fibrillin- fibrillar protein that forms microfibrillar sheath
cross linking proteins - desmisine and isodesmosine
found in blood vessel walls of large vessels
-so that it can maintain constant diameter
Structure of Elastic Fibers
elastin core surrounded by fibrillin
assembled in ECM
-fibrillin forms hollow structure that is then filled with elastin
Marphan Syndrome
genetic defect in fibrillin
-makes elastic fibers less stable
causes weakened aortic wall which can blow out
-aortic aneurysm
affected often tall, think, gangly, with long digits
Ground Substance
-composition?
glycosaminoglycans, proteoglycans, and adhesive glycoproteins
Glycosaminoglycan (GAGs)
long chain of unbranched polysaccharides
-repeating disaccharides
acid sugar and amino sugar
have negative charge which recruits sodium and other salts
- draws in water - hydrostatic pressure allows for turgor (stiffness)
Hyaluronic Acid
GAG that is HUGE!
-bc it is unsulfated
doesn’t covalently bind to proteins
Keratan Sulfate
GAG in cartilage, cornea, and intervertebral discs
Heparan Sulfate
GAG in blood vessels, lungs, basal lamina
heparin
mast cell granules, liver, lung, skin
Chondroitin-4 Sulfate
GAG in cartilage, bone, cornea, blood vessels
Chondroitin-6 Sulfate
GAG in cartilage, Wharton’s Jelly, and blood vessels
Dermatan Sulfate
GAG in heart valves, skin, and blood
Proteoglycan
GAG covalently bound to protein
Proteoglycan Aggregate
multiple GAGs can bind to long hyaluronic acid
-bind through a linking protein
adhesive glycoproteins
proteins linked to sugar that are binding and adhesive
help bind the cell to the ECM
fibronectin, laminin, intergrin, entactin, tenascin, chondronectin, osteonectin
Entactin
adhesive glycoprotien that binds laminin and collagen IV
Tenascin
adhesive glycoprotein
large hexamer, binds fibronectin and transmembrane proteoglycans
Chondronectin
adhesive glycoprotein
like fibronectin, binds collagen II, integrins, and GAGs
osteonectin
adhesive glycoprotein
like fibronectin, binds collagen I, integrins, and proteoglycans
binds calcium (hydroxyapatite) to collagen I in bone
Fibronectin
adhesive glycoprotein
dimer of nearly identical subunits bound end to end
links cells and ground substance
-binds integrins, collagen, heparan sulfate proteoglycan
involved in embryological cell migration
cells placed on fibronectin will have their cytoskeletal fibers align with the ECM
Laminin
adhesive glycoprotein
trimer of intertwined polypeptides (2 beta, 1 alpha)
links cells, fibers, and ground substance
in basal lamina (almost exclusively)
binds GAGs, proteoglycans, and other adhesive glycoproteins
Integrin
adhesive glycoprotein
heterodimeric integral membrane protein - no signal transduction
extracellular domain - binds ground substance
-activated by divalent cations
intracellular domain - binds cytoskeleton
-C-terminus binds intermediary proteins
Vinculin and Talin
bind to actin
play a role in integrins (adhesive glycoprotein)
Why are integrin bonds weaker?
weaker bonds allow more functional flexibility with integrins
-strong bonds causes permanent gluing
still strong because there are lots of weak bonds (overall strength)
Mesenchymal Connective Tissue
- relatively devoid of fibers
- most of ECM is ground substance
- stellate (star-shaped) pleuripotent (undifferentiated) cells
- will form numerous types of adult cells
Mucus Connective Tissue
- loose amporphous connective tissue
- lots of ground substance
- jelly like matrix Wharton’s Jelly
- found on umbilical cord
- not a lot of fibers
Wharton’s Jelly
jelly-like matrix in the Mucus Connective Tissue
Areolar Connective Tissue
aka loose connective tissue
- lots of ground substance
- found around glands and blood vessels (not very tight packed)
- fibroblasts, adipose cells, macrophages, mast cells
- loosely woven fibers
Dense Connective Tissue
greater density of fibers than loose connective tissue
-collagen fibers grouped in bundles
Dense Regular Connective Tissue
collagen in order arrangements
-highly ordered and densely packed
-found in:
tendons, ligaments, aponeurous
Dense Irregular Connect Tissue
collagen in random arrangements
found in:
dermis
capsule of organs
fascia
-multi-directional strength
Adipose Connective Tissue
little fiber or ground substance
dense in adipose cells (adipocytes)
Unilocular Tissue
white or brown fat
cells with single lipid droplet
predominant in humans
Multiulocular Tissue
brown fat
cells contain multiple lipid droplets
hibernating animals
Elastic Connective Tissue
highly elastic
- fibroblasts, collagen, elastic fibers (characteristic component)
- commonly found in walls of large vessels, nuchal ligament, and other elastic tissues
Reticular Connective Tissue
composed of fibroblasts, reticular fibers
-form framework for liver, adipose tissue, hematogenous tissue and other transient CT cells
reticulocytes
fibroblast that produces reticular fibers
Blood as a Connective Tissue
fibers - fibrinogen (converted to fibrin)
ground substance - GAGs (heparin), proteins (albumin)
fluid - plasma
