exam questions Flashcards
Importance of ECM composition in determining physical characteristics in CT disorder caused by defect in ECM
Connective tissue has two components, cells and ECM. SUpport cells of connective tissue produce ECM, from mesenchyme. Connective tissue proper produces fibrocytes (gives strength, gel like substance), cartilage produces chondrocytes (gell like substance that contain elastin for recoil & collagen for strength) & bone produces osteoclasts (gel like substance, thats calcified).
ECM is made of ground substance, adhesion glycoproteins & fibrillar proteins.
Ground substance is made of GAGs & proteoglycans. GAGs are long unbranched polysaccharide chains. Most common GAG is hyalornic acid.
Proteoglycans + Glycosaminoglycan covalently bond the GAGs & aid in volume and compression.
Fibrillar protins provide strength (collagen) & elasticity (elastin). Collagen is a series of twisted proteins giving strength. Type 1 collagen is around 90% of body, type 2 collagen is cartilage, tpe 3 cartilage is reticular fibres & type 4 is basement membrane.
Adhesion glycoproteins mediates cells between ECM and cytoskeleton. Fibronectin is dimeric glycogen where binding to collagen, proteoglycans + cells. Collagen binds integrin to cell surface. Laminin bind multiple component to ECM which form sheets to make basement membrane where cells bind to the basemment membrane through integrin.
Osteogenesis imperfcta: Brittle bone disease with a dificiency of type 1 collagen where less cllagen result in grafile bones. Mutation in COLA1 and COLA2 in type 1 collagen. Normal gene produce normal type 1-4 collagen. Type 1 gene produces 1/2 collagen; loss of collagen production but can still make triple helicies. Type 2&3 Can produce normal collagen but have a point mutation therefore the collagen being produced isnt effective.
Describe the classification of all epithelial tisseu types according to morphological criteria. Discuss how the structure of each type of epithelium is related to its function.
Epithelial tissues covers the cavities within our bodies, lines organs and external body such as the epidermind. Its a protective barrier with secretory and absorptive adaptations. Epithelia is classified through shape, layer, surface specialisation and thats how its function is based. Epithelia also has polarity which provide a basal and apical surface. Epithelia also has a basement membrane which anchors epithelia to the supportive Connective tissue. Epithelium is avascular which gets its nutrients through diffusion.
Apical polatiry linked to lumen is microvilli found in the small intestine aiding in absoprtion. Fingerlike projections on the plasma membrane. Light microscopy you can see the brushborder whereas in electron microscopy you can see the core of actin filaments of individual microvilli. 0.5-1ml. Cilia is also another apical feature. Non-motile sensation is for sensory information and motile sensation is for the remova of debris example in the esophagus. Composed of cytoskeletons of microtubules.
Basal polarity is linked to lamina at the bottom we’ll see basal folding and membrane plauqes which increase SA availble in membrane for exchange of products
Layers have their specific names such as simple (one layer), stratified (multiple), pseudostratified & transitional. Cell shape are cuboidal, squamous, columnar. Different epithelial tissues are connective, muscle, nervous & epithelial.
Simple squamous found in alveoli - thin areas - easy for diffusion.
Stratified squamous - found on skin.
Transitional epithelium - Changes between squamous or cuboidal depending on stretch part of bladder.
Pseudostraitifed - Multiple cells on top of eachother but not really as all cells need to touch BM - found in respiratory system.
Surface or glandular secretory epithelium. Singular goblet cells secreting mucus to a complex gland of acinar cells of pancreas.
Sacromere of skeletal muscle myofibril and changes during contraction.
Discuss gene mutation encoding myostatin impact of skeletal muscle size
Sacromere consists of two protein filaments, actin & myosin which are always active for muscle contraction.
Actin thin filaments which contain site for contraction such as troponin which sits on top of tropomyosin responds to signalsn and tropomyosin covers actin and binding site in relaxed state.
Myosin thick filaments consists of a elongated protein head which bind to actin molecule allowing contraction to occur.
Myofibrils are made of repetitive sarcomeres giving that striated appearance. Z
Z lines = Outside of sarcomere. M line = Between two Z lines. H band = Actin I band = Myosin H band - Overlap of both actin and myosin. In relaxed state both H & I bands are large as theres more area but during contraction theyre smaller as theres less area and the A band stays the same.
Muscle contraction pathway is
1) ACh is released due to signal coming down motor neurons which depolarises the cell so action potentials go through.
2) Through T-tubules, AP goes through the sarcomere reticulum releasing calcium which further binds onto actin and myosin.
3)Tropomyosin then changes it shapes exposing actin then myosin can now bind where contraction occurs.
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