L17. Tissues and Stem Cells Flashcards
explain the building blocks of multicellular organisms
cells -> tissue -> organ -> organ system -> organism
define tissue
- how multicellular organisms organize their cells
- they are composed of the extracellular matrix
tissue - extracellular matrix
- the tissue’s internal framework of cytoskeletal filaments
- gives supportive tissue’s their strength and provides one way to bind cells together
explain connective tissues
- extracellular matrix is plentiful in there cells
- different tissues have different types and quantities of collagen
- other molecules are interwoven with collagen
connective tissues - what is collagen
- a fibrous protein that is present in bone, tendon, and skin
- provides tensile strength to animal connective tissue
- most abundant extracellular protein in vertebrates
- 20 different collagens
- it is long, stiff, and triple-stranded
connective tissues - what molecules are interconnected with collagen
- elastin - a rubbery protein
- polysaccharide molecules
explain collagen production
- produced by a fibroblast cell
- synthesized intracellularly via exocytosis secretion
- outside of the cell, they assemble into aggregates
- the cell secretes collagen in its precursor form procollagen
- procollagen proteinase cuts off the terminal extensions to allow assembly of collagen fibril
what happens when there is a genetic defect in procollagen proteinase or procollagen
results in improper collagen assembly and lower tensile strength
how is collagen organized
they are organized by the cells that excrete it
collagen organization - skin
- they are woven in a wickerwork pattern or alternating layers
- this provides the skin with tensile strength in multiple directions
- fibroblasts can draw out the collagen into cables
collagen organization - in cell cultrure
- if you put pieces of embryonic tissue on a collagen gel along with fibroblasts, the fibroblasts will tug on the collagen and compact it
- this is important for wound healing
what are glycosaminoglycans (GAGs)
- they are negatively charged polysaccharides
- they are covalently linked to core proteins to form proteoglycans
- many GAG chains are attached to a single core protein
glycosaminoglycans (GAGs) - what areas have a lot/less
- tendon and bone: less GAGs and mostly collagen
- eye: lots of GAGs and less collagen
glycosaminoglycans - explain its properties
- GAGs are strongly hydrophilic and take up large amount of large volume relative to their mass
- they form hydrophilic gels by attracting cations (Na+) and water
polarized epithelia - define epithelia
- multicellular sheets in which the cells are joined together side to side
- the joined cells then create a barrier
