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03. PASSIVE DIFFUSION .... Adnan ahmad khan.pptx

  1. Guided by: DR. M.M. KHAN SIR(H.O.D.) DR. INDU MA’AM DR. PUSHPALATA MA’AM DR. RASHMI MA’AM DR. SAMREEN MA’AM DR. MAJID SIR DR. SANJEEV SIR Submitted by: Adnanahmadkhan Rollno. : 07(Mbbs ist year) PASSIVE DIFFUSION
  2. INTRODUCTION  Diffusion is the chemical process by which passive transport occurs.  Passive transport is the transportof the substancesalong the concentrationgradient or electrical gradient or both.  It is also knownas diffusion or downhill movement.
  3. TYPES OF DIFFUSION  There are 2 types of Diffusion;  Simple Diffusion/ Passive diffusion  Facilitated diffusion
  4. CLASSIFICATION SIMPLE DIFFUSION/PASSIVE DIFFUSION  Occurs either through lipid layer or protein layer of the cell membrane. Lipid layer : It is permeable only to the lipid soluble substances like oxygen , carbon dioxide and alcohol. Protein layer: It is permeable to water soluble substances ,mainly electrolytes diffuse through this layer.
  6. PROTEIN OR ION CHANNELS They have pores that allow passage of ions and small water soluble molecules. Called as protein channels as they are lined by protein molecules. Charcteristic feature : selective permeability
  7. REGULATION OF CHANNELS o Some of the protein channels are continuously open and most of the channels are always closed. o Continuously opened channels : Ungated channels o Closed channels : Gated channels (These channels are opened only when required)
  8. Gated channel : Types  Voltage gated channels : >Open whenever there is a change in electrical potential.  Ligand gated channels : >Open in the presence of some hormonal substances / ligands.  Mechanically gated channels : >Opened by some mechanical factors.
  9. FACILITATED DIFFUSION  Water soluble substances having larger molecules are transported through the cell membrane with the help of carrier proteins.  GLUCOSE and AMINO ACIDS are transported by facilitated diffusion.  Diameter of these molecules > Diameter of the channels So these molecules cannot diffuse through them.
  11. FACTORS AFFECTING RATE OF DIFFUSION 1. Permeability of cell membrane 2. Temperature 3. Concentration/Electrical gradient of substances across the cell membrane 4. Solubility of the substance 5. Thickness of the cell membrane 6. Size of molecules 7. Size of ions 8. Charge of ions
  12. PASSIVE TRANSPORT : SPECIAL TYPES  BULK FLOW- Movement of large quantity of substances from region of high pressure to region of low pressure. eg:exchange of the gases across the respiratory membrane in the lungs.  FILTRATION- Movement of water and solutes from an area of high hydrostatic pressure to an area of low hydrostatic pressure. eg- occurs in glomerulus of kidneys
  13. OSMOSIS  Movement of water or any other solvent from area of low concentration to area of high concentration of solute through semi- permeable membrane. TYPES 1.ENDOSMOSIS 2.EXOSOMOSIS
  15. REFERENCES : $ Guyton and Hall $ Sembulingam