connective tissue lecture fall 2012.docx

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University of Toronto Scarborough
Biological Sciences
Stefan Rusyniak

CONNECTIVE TISSUE LECTURE NOTES Reticular fibers are important because they make up the network upon which cells of fibers rest on. - Mesh! - Lots of branching of type 3 collagen fibers - Mesh acts as a filter - All organs have these networks – spleen filters out old or damaged blood cells (senescent – old) - What stain is good for showing ultra structure of things? That that’s based on silver - Reticular fibers are stained with silver – therefore are called argyophillic Elastic fibers are important because that ability to recoil is important!! - They contain elastin that is scaffolded onto fibrillin - Scaffold means framework - Fibrillin creates structure scaffold on which elastin fibrils are arranged - Easy way to think of it : spandex – 100% cotton shirt and you wear it and stretch it out of shape but elastic fibers that have hint of spandex that help to maintain shape of things - Just like spandex you don’t need a lot of it but a little bit of it just for the hold of it - Where is this super impnt? In your large blood vessels – so impnt that they lie just under the epithelium basement membrane because heart doesn’t pump constant blood – when you exercise the # doubles, aorta has to expand to accommodate extra fluid and recoil and that recoiling capability comes from an elastin fiber. Clinical connection: aging skin - Photo protected – protected against sunlight - Fibrillin is extremely susceptible to photo aging – damage by uv light - Fibrillin is the scaffold upon which elastin can rest so if fibrillin is degrading, elastin doesn’t have anything to be arranged on. - This is considered intrinsic aging and extrinsic aging - Intrinsic aging – inevitable physiological process - Extrinsic – exposed under sun so increases (leathery skin , deep wrinkles, sagging) - Scaffold is breaking down so elastin cant maintain the structure - What happens to skin as you age? Lose elasticity and MOISTURE because you’re losing hyronic acid - So do anti aging creams work even though they say they have that acid and collagen? - Protection from sunlight is #1 way and moisturizing. Cells at the bottom are very different from top layer, cells at bottom (esp in stratified squamous epithelium (skin, areas of high stress)) o Top layer of stratified squamous epi. Is continuously being scraped off but it’s being replaced by the basil layer (cells at bottom) o Any products you put on top of skin is penetrating 5 – 7 layers of upper skin o Nutrition helps basil layer – hydration, vitamin C, essential fatty acids, maintaining germinal layer – one that divides. - Unbreakable o Samuel l Jackson in the movie has brittle bone disease – osteogenesis imperfect ( autosomal dominant disorder that causes deficiencies in type 1 collagen production) o Type 1 is most abundant collagen and these ppl have lot of problems, even while still a fetus, these pp
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