Extracellular Matrix Flashcards
What is the ECM composed of?
a 3D network of polysaccharides and proteins
The ECM is similar to an individual cell’s _____ because it offers support for cells, guides movement, and gives the cell information.
cytoskeleton
The ECM supports what?
Epithelial cells, peripheral nervous cells, adipose cells, muscle cells
Epithelial tissue is found covering the surface of ___ and ___ ___ and lining ____.
organs, blood vessels, cavities
What is connective tissue?
The cells and ECM involved in connecting tissues in organs
What are three examples of connective tissue?
Bones, blood cartilage
What are the four functions of epithelia?
Filtration, gas exchange, barrier, absorption/secretion
The ECM is thick in _____ tissue and not as dense in tightly packed epithelial cells.
connective
The free surface of epithelial cells is called the ____ surface, and the attached surface is called the ____ surface.
apical, basal
What two layers separate the epithelia from the connective tissue? What are they each composed of?
Basal lamina (composed of proteins secreted by epithelial cells) and reticular lamina (composed of proteins secreted by connective tissue cells)
What are the basement membrane’s two main purposes?
Hold the epithelia to the connective tissue and guide the cell during migration
Collagen’s structure is three left-handed ______ in a triple _____-____ turn.
alpha helices, right-handed turn
What amino acid is significant in collagen?
Glycine
Explanation: need a small amino acid to fit into the turns
What is most common collagen type?
Type I
Which layer of the basement membrane has collagen IV?
basal lamina
Collagen VII is necessary to attach the _____ _____ to the underlying connective tissue.
basement membrane
Where in the body is Collagen I found?
bones, cartilage (very structural)
This type of collagen is also called fibril forming collagen.
Collagen I
What is the AA structure/sequence of Collagen I?
Many repeating Gly-X-Y segments. No N or C terminus.
Network forming collagen is another name for Type __ collagen. Why?
IV.
There are more breaks in the Gly-X-Y repeats.
Which organ is full of Collagen IV?
kidneys
How is the mesh assembly of collagen IV achieved?
Combining dimers and tetramers
How is collagen VII similar to types I and IV?
Has more Gly-X-Y repeats than IV but keeps the non-collagenous domains like IV
Which type of collagen is defective in each of these disorders:
- Osteogenesis imperfecta
- Alport syndrome
- Dystrophic epidermolysis bullosa
- Type I. (Gly in repeats is changed to a Ser. Weak bones, always breaking.
- Type IV. (Kidney and hearing problems).
- Type VII. (VII connects basement membrane and connective tissue. Blisters form very easily in the dermis beneath the basement membrane)
Glycosoaminoglycans are repeating _______ that are heavily ____ which attracts positively charged ions like ____. The movement of these ions brings water along as well. This is why GAGs are found in _____ as lubrication.
disaccharides, sulfated, sodium, joints
Proteoglycans are important for _____ and ______.
signalling, regulation
What is the structure of a proteoglycan?
A core protein surrounded by GAG chains (there is more sugar than protein in a proteoglycan)
Where are proteoglycans found?
In cells, on cell surfaces (binding to things like fibronectin), and throughout the ECM (in joint ECM for lubrication)
What is the major proteoglycan in cartilage associated with arthritis when broken down?
aggrecan
What is necessary for growth factor receptor recognition?
free growth factor must bind to a proteoglycan before attaching to the receptor
Which proteoglycan is used in angiogenesis?
heparan sulfate
The elastic fiber of the body. Involved in Marfan syndrome.
Fibrillin
Where is fibrillin found?
Aorta, eye lens, periosteum (bone covering), skin
Firbrillin sequesters ____ ____ until needed. In Marfan, fibrillin is defective, and bones grow more than they need to.
growth factors
Fibronectin is the glue of the body. It is a ____ connected by disulfide bonds. There are ___ isoforms created by a single gene but variations are from ______ _____ _____. This protein is found in _____ and is necessary for clotting.
dimer
20
alternative mRNA splicing
platelets
What is the connection between fibronectin and premature births?
Fetal fibronectin keeps the fetal sack attached to the uterine lining. After 20 weeks, fibronectin in vaginal discharge should go down, but if this does not decrease, there is risk of premature birth.
What three different types of proteins have binding domains on fibronectin?
Collagen, proteoglycans, and integrins
Defects in any of the three _____ chains (alpha, gamma, beta) can cause junctional epidermolysis bullosa.
laminin
Laminin is found in the ____ ____ and connects the epidermis and dermis.
basal lamina
Why do tumor cells have laminin and collagen fragments on their surfaces?
Trying to adhere to everything
Matrix metalloproteins are in active unless they have ___/___.
Zinc or calcium
What are the three ways MMPs are regulated?
mRNA, tissue inhibitors of metalloproteinases (TIMPS keep MMPs localized), and limited quantity
What diseases are associated with too much MMP activity?
arthritis, CVD, cancer metastsis
What are the three classic stages of wound repair?
inflammation, proliferative, remodel
What are the two forms of fibronectin?
Matrix (secreted by fibroblasts; connect cells via integrins to the ECM) and plasma
Which type of fibronectin is found in the inflmattory stage?
plasma
Explanation: blood clotting. When wounded, fibronectin becomes active and extends into a fibrous form. Connects to fibrin and platelet aggregates
During the inflammatory and proliferation stages, fibroblasts secrete _____ ____ to create the scab and new tissue scaffold.
collagen III
In the remodel phase, fibronectin and collagen III are replaced by ____ ____.
Collagen I
What role do MMPs play in wound repair?
ECM digestion to offer direction during cell migration and tissue remodeling
