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11.10 (dr. husun bano)transport of substances across cell membrane
 

11.10 (dr. husun bano)transport of substances across cell membrane

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    11.10 (dr. husun bano)transport of substances across cell membrane 11.10 (dr. husun bano)transport of substances across cell membrane Presentation Transcript

    • TRANSPORT OF SUBSTANCES THROUGH CELL MEMBRANE (PASSIVE DIFFUSION) Husn Bano Assistant Professor Deptt Physiology Sindh Medical College ,DUHS
    • TRANSPORT THROUGH CELL MEMBRANE
      • TYPES:
      • PASSIVE TRANSPORT
        • Simple diffusion
        • Facilitative diffusion
        • Osmosis
    • 2. Active Transport
      • Primary active transport
        • e.g. Co-transport
        • Na + -K + pump
        • Secondary active transport
        • (Counter transport)
        • Na + -H +
    • continue
      • 3. Endocytsis:
      • Pinocytosis
      • Phagocytosis
      • 4 . Exoytsis
      • 5. Bulk Flow
    • STRUCTURE OF CELL MEMBRANE
    • PASSIVE DIFFUSION
      • DEFINATION:
      • It is the process through which both solute and solvent molecules move from higher conc. to lower concentration.
      • TYPES OF PASSIVE DIFFUSION:
      • Simple diffusion
      • Facilitated diffusion
    • 1: SIMPLE DIFFUSION
      • Simple diffusion means that molecules move from higher concentration to lower conc. through “PORES” or “INTERCELLULAR SPACE” of cell membrane.
      • OR
      • Random movement of molecules from higher to lower concentration.
    • SIMPLE DIFFUSION
    • A: SIMPLE DIFFUSION THROUGH LIPID BILAYER
      • CO 2
      • O 2
      • N 2
      • ALCOHOL
      • H 2 O……? (molecular size 0.3nm)
    • TRANSPORT OF H 2 O AND OTHER LIPID INSOLUBLE SUBSTANCES
      • H 2 O……? (molecular size 0.3nm)
      • Like H 2 O other lipid insoluble substances passes through lipid bilayer, if their molecular size is very small.
    • B: SIMPLE DIFFUSION THROUGH PROTEIN CHANNAL
      • All the water soluble substances except charged particles (electrolytes) passes through protein channels , not through lipid bilayer.
    • Reason of impermeability of charge particles
      • They are hydrated ions.
      • Outer pole of lipid bilayer have negative charge………
      • Hydrated Cl - (molecular size 3.6nm)
    • Protein Transporters 1) Channels 2) Carriers a) open b) gated
    • TRANSPORT THROUGH GATED PROTEIN CHANNELS.
      • Sodium (Na + )
      • Potassium (K + )
      • Calcium (Ca ++ )
      • Chloride (Cl - )
      • ACTUAL MOLECULAR SIZE / Hydrated Size
      • Na + 0.34nm 5.2nm
      • K + 0.36nm 3.9nm
      • Cl - 0.32nm 0.36nm
    • MODEL OF SODIUM CHANNEL
    • FLOW OF POTASSIUM IONS
    • 2: FACILITATED DIFFUSION
      • Definition : is the transport mechanism which require “CARRIER PROTEIN”
      • Mechanism:
      • Molecule + CARRIER PROTEIN
      • Conformational change in carrier protein
      • Molecule detached from carrier
      • No energy or ATP requried
    • FACILITATED DIFFUSION
      • Glucose
      • Amino acids Other simple carbohydrates such as :
      • Glactose
      • Mannose
      • Arabinose
      • Xylose.
      • All require “carrier protein” for their transport, so called “carrier mediated diffusion”
    •  
    • FACILITATED DIFFUSION verses SIMPLE DIFFUSION
      • Facilitated diffusion require “CARRIER”
      • Facilitated diffusion always have Vmax
      • Simple diffusion Facilitated diffusion
    • Factors affecting rate of diffusion
      • 1 Permeability of membrane
      • 2 Concentration difference
      • 3. Pressure difference
      • 4 Electrical difference
    • Factors Affecting On Permeability of membrane
      • 1.Thickness of membrane
      • 2. Lipid solubility
      • 3 Numbers of protein channels.
      • 4 Temperature
      • 5 Square root of molecular weigh
      • 6 Crossectional area of membrane
    • Special categories of transport
      • 1. BULK TRANSPORT :
      • It is the transport mechanism in which large quantity of substances transported from high pressure to low pressure e.g Gases exchange through respiratory membrane
    • ENDOCYTOSIS
      • Large molecule or macromolecules transported by endocytosis.
      • Endocytosis are of 3 types
      • a. Pinocytosis
      • b. Phagocytosis
      • c. Receptor mediated endocytosis
    • PINOCYTOSIS (Cell drinking)
      • 1. Large bacteria or antigen( in the form of droplet fluid) bind with outer surface of membrane.
      • 2 Cell memb. Evaginate arround the droplets
      • 3 It is detached from cell memb.,forms ENDOSOME.
    • PINOCYTOSIS (Cell drinking) Cont..
      • 4. Primary lysosomse attach with edosome ,converted into secondry lysosomes.
      • 5. Hydrolytic enzymes present in secondary lysosome becomes activated and digest the content of endosome
    • PINOCYTOSIS (Cell drinking)
    •  
    • PHYGOCYTOSIS (Cell eating)
    •  
    • RECEPTOR MEDIATED ENDOCYTOSIS
      • The End
      THANK YOU