bm 2251 bio medical instrumentation n.
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  1. BM 2251-BIO MEDICAL INSTRUMENTATION • G.THIYAGARAJAN • BM17-Lecturer • Department of Biomedical Engineering BME REC

  2. Cell Structure & Function BME REC

  3. Cell Theory • All living things are made up of cells. • Cells are the smallest working units of all living things. • All cells come from preexisting cells through cell division. BME REC

  4. Definition of Cell A cell is the smallest unit that is capable of performing life functions. BME REC

  5. Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell BME REC

  6. Two Types of Cells Prokaryotic Eukaryotic BME REC

  7. Prokaryotic • Do not have structures surrounded by membranes • Few internal structures • One-celled organisms, Bacteria BME REC

  8. Eukaryotic • Contain organelles surrounded by membranes • Most living organisms Plant Animal BME REC

  9. “Typical” Animal Cell BME REC

  10. “Typical” Plant Cell BME REC

  11. Glycoprotein Glycolipid Transmembrane proteins Peripheral protein Filaments ofcytoskeleton Membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Extracellular fluid Phospholipids Cholesterol Cytoplasm BME REC

  12. Many Functions of Membrane Proteins Outside Plasma membrane Inside Transporter Enzymeactivity Cell surfacereceptor Cell adhesion Cell surface identity marker Attachment to thecytoskeleton BME REC

  13. Movement across the Cell Membrane BME REC

  14. Diffusion • 2nd Law of Thermodynamicsgoverns biological systems • universe tends towards disorder (entropy) • Diffusion • movement from highlow concentration BME REC

  15. Diffusion • Move from HIGH to LOW concentration • “passive transport” • no energy needed movement of water diffusion osmosis BME REC

  16. Diffusion across cell membrane • Cell membrane is the boundary between inside & outside… • separates cell from its environment NO! Can it be an impenetrable boundary? OUT waste ammonia salts CO2 H2O products IN food carbohydrates sugars, proteins amino acids lipids salts, O2,H2O OUT IN BME REC cell needs materials in & products or waste out

  17. inside cell outside cell Diffusion through phospholipid bilayer • What molecules can get through directly? • fats & other lipids • What molecules can NOT get through directly? • polar molecules • H2O • ions • salts, ammonia • large molecules • starches, proteins lipid salt NH3 sugar aa H2O BME REC

  18. Channels through cell membrane • Membrane becomes semi-permeable with protein channels • specific channels allow specific material across cell membrane inside cell H2O aa sugar salt BME REC outside cell NH3

  19. high low Facilitated Diffusion • Diffusion through protein channels • channels move specific molecules across cell membrane • no energy needed facilitated = with help open channel = fast transport BME REC “The Bouncer”

  20. low high Active Transport • Cells may need to move molecules against concentration gradient • shape change transports solute from one side of membrane to other • protein “pump” • “costs” energy = ATP conformationalchange ATP BME REC “The Doorman”

  21. Active transport • Many models & mechanisms ATP ATP antiport symport BME REC

  22. Getting through cell membrane • Passive Transport • Simple diffusion • diffusion of nonpolar, hydrophobic molecules • lipids • high  low concentration gradient • Facilitated transport • diffusion of polar, hydrophilic molecules • through a protein channel • high  low concentration gradient • Active transport • diffusion against concentration gradient • low  high • uses a protein pump • requires ATP ATP BME REC

  23. Transport summary simplediffusion facilitateddiffusion ATP activetransport BME REC

  24. How about large molecules? • Moving large molecules into & out of cell • through vesicles & vacuoles • endocytosis • phagocytosis = “cellular eating” • pinocytosis = “cellular drinking” • exocytosis BME REC exocytosis

  25. Endocytosis fuse with lysosome for digestion phagocytosis non-specificprocess pinocytosis triggered bymolecular signal receptor-mediated endocytosis BME REC

  26. The Special Case of WaterMovement of water across the cell membrane BME REC

  27. Osmosis is diffusion of water • Water is very important to life, so we talk about water separately • Diffusion of water from high concentration of water to low concentration of water • across a semi-permeable membrane BME REC

  28. hypotonic hypertonic Concentration of water • Direction of osmosis is determined by comparing total solute concentrations • Hypertonic - more solute, less water • Hypotonic - less solute, more water • Isotonic - equal solute, equal water water net movement of water BME REC

  29. Managing water balance • Cell survival depends on balancing water uptake & loss BME REC freshwater balanced saltwater

  30. Managing water balance • Isotonic • animal cell immersed in mild salt solution • example:blood cells in blood plasma • problem: none • no net movement of water • flows across membrane equally, in both directions • volume of cell is stable BME REC balanced

  31. Managing water balance • Hypotonic • a cell in fresh water • example: Paramecium • problem: gains water, swells & can burst • water continually enters Paramecium cell • solution: contractile vacuole • pumps water out of cell • ATP • plant cells • turgid ATP BME REC freshwater

  32. Water regulation • Contractile vacuole in Paramecium ATP BME REC

  33. Managing water balance • Hypertonic • a cell in salt water • example: shellfish • problem: lose water & die • solution: take up water or pump out salt • plant cells • plasmolysis= wilt BME REC saltwater

  34. Action and resting – Potential propagation of action potential • An action potential (also known as a nerve impulse or a spike) is a self-regenerating wave of electrochemical activity that allows excitable cells (such as muscle and nerve cells) to carry a signal over a distance. It is the primary electrical signal generated by nerve cells, and arises from changes in the permeability of the nerve cell's axonal membranes to specific ions. Action potentials are pulse-like waves of voltage that travel along several types of cell membranes BME REC

  35. Relatively static membrane potential of quiescent cells is called resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomenona called action potential and graded membran potential. BME REC

  36. Electrode –Electrolyte Interface BME REC

  37. Half-Cell Potentials BME REC

  38. Silver –SilverChloride BME REC

  39. Ionic ActivityRelative half-Cell Potentials BME REC

  40. Electrode Behavior BME REC

  41. Frequency Dependency BME REC

  42. Electrode Skin Interface BME REC

  43. The electric Model BME REC

  44. Motion Artifacts BME REC

  45. Biopotential Electrodes BME REC

  46. Biopotential electrodes BME REC

  47. Suction Electrode BME REC

  48. Floating Electrodes BME REC

  49. Flexible Electrodes BME REC

  50. Internal Electrodes BME REC