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human cell.pptx
- 1. Structure of humancell & functions
- 12. • 5. Providesa framework for the arrangement of an ordered sequence of protein molecules e.g. enzymes,pumps,receptors,ions,channels, in a functionally meaningful pattern. • 6.Links adjacent cells together by junctional complexes to form tissues.
- 32. Tight junction • Inthis membranes of two cells become opposed & outer layers of membranes fuse strongly,thus obliterating the space between the cells. • Seen along the apical margins of cells in epithelium like intestinal mucosa,walls of renal tubules. • Forms barrier to the movement of ions and other solutes from one side of epithelium to other.
- 33. Desmosomes or Adherensjunction • Here two membranes are separated by 15-20nm space. • There is dense accumulation of proteins on both surfaces of membrane with fibers extending from cytoplasmic surface of each membrane into the cell. • Transmembrane glycoproteins called cadherins joins the cells. • This holds adjacent cells firmly together in areas that are subjected to stretching like skin. • Also resist separation during various contractile activities such as when food moves through the GIT.
- 34. Gap junctions orNexus • There is 2-20nm space between the opposing membranes. • This gap is filled with densly packed particles through each of which there appears to be a channel(tiny fluid filled tunnels) that connects the two cells. • The diameter of each channel is regulated by ca++,PH,and voltage. • Permits rapid propagation of electrical potential changes from one cell to another e.g cardiac & smooth muscle cells. • Also permits the direct transfer of ions and other small molecules up to MW1000 e.g sugars,amino acids between the cells without traversing the extracellular space.
- 38. Functions of CAM”S •Role in embryonic development. • Formation of nervous system. • Holding tissues together. • Inflammation & wound healing. • Metastasis of tumours. • Cells with abnormal CAMs have a higher rate of apoptosis.
- 41. • Abnormal apoptosisoccurs in autoimmune diseases,degenerative diseases and cancers.
- 42.