CAS BI 105 Lecture Notes - Lecture 4: Ultimate Tensile Strength, Elastin, Fibronectin
30 Apr 2018
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9/30: Multicellularity
ECM
•Animal Cells
•Cells secrete glycoproteins into extraceullar fluid, weaving them together to form matrix
•Cells express integrins on mb, attach to ECM
•Provides strength and rigidity to tissues
•ex: cartilage/bone/skin
•Organize cells, allow them to move/stay in place
•Provide signals to cells to guid function/development
•Contains adhering proteins
•Stick components of the ECM together and cells to ECM
•Fibers throughout offer structure for cell support, keep cells together, resiliency
•Contains structural proteins
•Give the tissues strength and elasticity
Proteins of ECM
Fibronectin - connects cells to ECM, organizes components
Laminin - connects cells to ECM, organizes components. found in top layers of skin
Collagen - provides tensile strength in deep skin/organs/bones/cartilage/tendons
Tensile strength of tissue
25% of total protein mass in body
75% of protein in skin
ex: leather = collagen
How is collagen made?
Cells produce individual collagen fivers
Immediately organizes into a triple helix
Outside the cell, collagen helices organize into larger collagen fibers
Elastin - forms elastic fibers for stretch and recoil
Importance
Stretch and recoil
skin, some cartilage, blood vessels, anywhere that is subject to frequent stretch (ex:
arteries)
Loss of elastin - sped up by toxins (ex: nicotine) and UV damage
Proteoglycans
ECM also contains polysacharides
repeated disaccharide units attached to central protein
Weave together and bind water, creating a gel that cushions cells and organs
Cell Attachments
Cells attach to each other and the ECM
Tight Junctions
Desmosomes
Gap Junctions
Anchoring Junctions
Connect cells to ECM
Specifically, membrane proteins called interns connect cytoskeleton o ECM proteins
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
75% of protein in skin ex: leather = collagen. Fibronectin - connects cells to ecm, organizes components. Laminin - connects cells to ecm, organizes components. found in top layers of skin. Collagen - provides tensile strength in deep skin/organs/bones/cartilage/tendons. Elastin - forms elastic fibers for stretch and recoil. Outside the cell, collagen helices organize into larger collagen fibers. Stretch and recoil skin, some cartilage, blood vessels, anywhere that is subject to frequent stretch (ex: Loss of elastin - sped up by toxins (ex: nicotine) and uv damage. Ecm also contains polysacharides repeated disaccharide units attached to central protein. Weave together and bind water, creating a gel that cushions cells and organs. Cells attach to each other and the ecm.
