10.2 Extracellular Matrix Flashcards
What is the extracellular matrix (ECM)?
not a cell or part of the cell (outside the cell) made up of material known as ground substance along with a variety of types of imbedded protein fibers.
-ECM is made up by cells and plays a significant role in determining the behavior of cells in it.
What is connective tissue?
Connective tissue forms most of the extracellular matrix material in our bodies. It has a variety of roles, including the formation of conduits for nerves and blood cells.
It also provides supporting material for cellular organs such s the liver and kidney and
It performs a variety of mechanical roles in our bodies, including the formation of:
1) the skeletal systems
2) Tendons and ligaments
What is a basal lamina?
layer of extracellular matrix material that is found at the base of all epithelial and endothelial cells. Sometimes it’s called basement membrane. This fibrous sheet of material separates an epithelial tissue from the underlying connective tissue.
Which protein is found in abundance in the connective tissue?
Collagen Type 1
What proteins/structures can you find in connective tissue?
Collagen Type 1
Blood vessels
Nuclei fibroblasts
What is the role of the fibroblasts in connective tissue?
fibroblasts are the cells that are responsible for making the connective tissue. They do so by producing collagen fibers.
Fibroblast or spindly or pointy in appearance
How do fibroblasts and other cells navigate through the extracellular matrix?
To navigate through the matrix the secrete proteases which digest the fibers and other components of the extracellular matrix
What are chondroblasts?
cells that make cartilage and when they become imbedded in the cartilage material they’re called chondrocytes
What are osteoblasts?
cells that form bone. When osteoblast become embedded in bone material they’re called osteocytes
What three major components comprise ground substance?
Which makes up most of the ground substance?
1) Glycosaminoglycans or (GAGs)
2) Glycoproteins
3) Proteoglycans
GAGs make up most of the ground substance
What is the structure of GAGs (glycosaminoglycans)? What other major characteristic stands out about GAGs?
a long chain of sulfated polysaccharides, which consist of a disaccharide of some type, strung together in a long row.
The types of sugar disaccharides that are used to form these chains determine what type of a glycosaminoglycan it is.
CHARACTERISTIC:
They have many negative charges. These negative charges attract sodium ions, which is positively charged, and in turn sodium will attract water.
What are examples of glycosaminoglycans (GAGs)?
1) Hyaluronan
2) chondroitin sulfate (found in cartilage)
3) dermatan sulfate (found in skin)
4) Keratan sulfate (found in eptihelial)
How do glycosaminoglycans (GAGs) form gel like material in the extracellular matrix? Why is this significant?
GAGs have many negative charges, which attracts sodium. Sodium invites water to the party. This causes GAGs to form a gel-like material when they’re swollen with water.
The gel material gives the extracellular matrix its physical properties. Resists compression factors
What is hyaluronic acid?
the simplest GAGs. it is a linear chain of linked disaccharides, other gags are not present as a simple linear chain (instead they form more complex structures)
What are proteoglycans and how are they formed?
Type of glycosaminoglycans.
It is formed by linking a simply glycosaminoglycan to a protein core. There are many diff proteins that can form the core and a variety of glycosaminoglycan side chains can be linked to the core, and this gives the extracellular matrix its molecular complexity.
How are glycosaminoglycan side chains in proteogylcans linked to the core protein?
via a special tetra-saccharide (it has four sugar moieties), which forms an adaptor link between the glycosaminoglycan side chain and the core protein.
Makes proteoglycans diverse. in configurations.
What are proteoglycan aggegates? How are they formed?
the most complex GAG. They are proteoglycans which are then linked back to a central hyaluronic acid molecule.
FORMED:
They are formed by linking core proteins to a GAG core with linker proteins. For example protegylcans are linked to a central hyaluronic acid molecule. They are linked by linker proteins. They are very large molecules! about 15 microns long
(WILL BE ON EXAM FOR SHIZZLE)
What are the functions of GAGs?
GAGs perform variable functions.
1) Fill up spaces that are not occupied by other cells or fibers. This is a function that’s obvs when you consider their size.
2) Attract salt ions and water and maintain Na+/H2O balance of tissues
3) Regulate proteins found w/in extracellular matrix. ( EX:
1) immobilize proteins and limit their range of activity or protect them from degradation aka prolonging their activity)
2) Inactivate protein/signaling factors by binding to them until they’re worked on by other cells in the matrix
3) Concentrate proteins in a limited area
What types of issues can occur if GAGs don’t regulate Na+/H2O balance in tissues?
deregulation of this balance can cause metabolic abnormalities, tissue edema, which is filling of tissues with free water.
What bodily process shows the functions of glycosaminoglycans (GAGs)
Inflammation in response to local infection.
Cells in the region around an infection site release signaling molecules like inflammatory cytokines, and other cells of the immune system need to hone in on these signals in a directional manner, and so the signaling has to be present at a high concentration in the area of the infection and then the concentration has to dwindle as you move away from the infection site. If the inflammatory cytokines were able to move freely and rapidly throughout the entire body, the information contained in this concentration gradient would be spread out and lost.
How do glycosaminoglycans form barriers that influence the movement of fluid across tissue? What is a bodily process that shows this?
b/c glycosaminoglycans interact so strongly with water molecules (the eff w/water)
Ex: the filtration apparatus of the kidney.
The primary filtration site in the kidney is a structure called the glomerulous. The core glomerulous is a know of permeable capillary tubes and surrounding these capillaries is a unique cell type called a podocyte.(which wraps capillaries with finger like protrusions)
Podocytes are very leaky. but the basement of these are filled with perlecan, which is a GAG
In healthy individuals, fluid which contains metabolic byproducts will leak through this filter, but the filter excludes things like red blood cells and even larger proteins. If you get defects in this barrier then proteins and even bllood cells will begin to show up in the urine.
What are glycoproteins
(fibronectin and laminin) are large proteins w/many adhesion sites for fibers, GAGs, and cell surface receptors. Their function is to link all of these components together physically.
Glycoproteins have small amounts of polysaccharides. these polysaccharides are much smaller than the long chains which form glycosaminoglycans
What is the structure of laminin?
A trimer of three subunits known as alpha, beta, and gamma chains. The trimer forms an extended coiled coil domain and is characterized by numerous globular domains that serve as binding sites for the ECCM
Where is laminin most commonly found?
epithelial cells. It underlies epithelial cell monolayers. it is abundant in and helps form basal lamina. Laminin is also recognized by other cell integrins
