Lecture 3 - Passive Transport (Helwan National University)

Faculty of Medicine Academic Year: 2024-2025 Year: 1 Semester: 1 Module: Human Body Function (HBF) 102  PASSIVE TRANSPORT By: ASHRAF ALGENDY PROFESSOR Department: MEDICAL PHYSIOLOGY 11/17/2024 2  OBJECTIVES A...

Faculty of Medicine Academic Year: 2024-2025 Year: 1 Semester: 1 Module: Human Body Function (HBF) 102  PASSIVE TRANSPORT By: ASHRAF ALGENDY PROFESSOR Department: MEDICAL PHYSIOLOGY 11/17/2024 2  OBJECTIVES At the end of the lecture you will be able to:  Clarify the importance of biological transport.  List biological membranes that encircle different compartments of the body fluid.  List different types of transport.  List and describe different types of passive transport.  Describe different types of passive transport. 23/11/2024 HBF - 102 3  Introduction Importance of transport 1- It supplies the tissues with oxygen and nutrients 2- It removes waste products and carbon dioxide. 3- It is a way of communication between different tissues.  Introduction Importance of transport 4- Immunity. 5- Secretory products have essential physiological function.  Introduction Transport in our body occurs through two type of membrane: 1-Capillary membrane 2-Cell membrane between plasma and between ICF and ISF tissue fluid(ISF). 11/18/2024 Helwan Special Medical Program 8 11/18/2024 Helwan Special Medical Program 9  Transport passive active does not need energy Need energy Down hill transport Mostly uphill transport pass from high concentration to Pass from low concentration to low concentration high concentration Passive transport Passive transport -It does not need energy -The substances pass from high concentration to low concentration -Down hill transport. Passive transport Passive transport Simple diffusion Facilitated diffusion osmosis Filtration( bulk flow) Solvent drag Passive transport diffusion Diffusion -It is ability of substance to expand to fill available space or it is ability of substances to pass from high concentration to low concentration. -Down hill transport. -It does not need energy Passive transport diffusion Diffusion simple Facilitated Does not need energy Does not need carrier Need carrier Passive Transport simple diffusion Simple Diffusion The main force of simple diffusion is a random thermal motion that result from self kinetic energy Passive Transport simple diffusion Simple Diffusion Transport of lipid soluble substance through lipid bilayer Transport of small uncharged lipid insoluble substance through lipid bilayer Transport of ions through channels. Transport across cell membrane through channel Click icon to add picture Question: Which of the following substance can pass through cell membrane by simple diffusion: a. CO2. b. Glucose. c. Amino acids. d. Protein. e. Poly peptide hormones. Passive Transport facilitated diffusion Facilitated Diffusion Transport of glucose across cell membrane using glucose transporters Transport of amino acid across cell membrane using amino acid transporters Transport of urea across cell membrane using urea transporter Passive transport facilitated diffusion Criteria Of Facilitated Diffusion Saturation Stereo specificity competition Passive transport facilitated diffusion Criteria Of Facilitated Diffusion Saturation stereo specificity competition Passive Transport Criteria of Facilitated Diffusion Saturation : a carrier has a limited number of binding site for solute Saturation has TRANSPORT MAXIMUM Passive transport facilitated diffusion Criteria Of Facilitated Diffusion saturation Stereo specificity competition Passive Transport Criteria of Facilitated Diffusion Stereo specificity: each carrier is specific for certain substance or even to certain isomer of molecule Passive Transport Criteria of Facilitated Diffusion Glucose carrier transport glucose only and cannot transport amino acid. Glucose transporter in renal proximal convoluted tubule transport only D-isomer (natural) of glucose. In contrast it is not able to transport L-isomer of glucose(unnatural). Passive transport facilitated diffusion Criteria Of Facilitated Diffusion saturation stereo specificity competition Passive Transport Criteria of Facilitated Diffusion competition: the specific site of certain molecule on a carrier could be occupied by another chemically related substance. Later substance could inhibit the transport of original molecule Passive Transport Criteria of Facilitated Diffusion competition: the specific site of certain molecule(D-glucose) on a carrier could be occupied by another chemically related substance(D-galactose). D-galactose could inhibit the transport d-glucose Question: Which of the following substance can pass through cell membrane by facilitated diffusion: a. CO2. b. O2. c. Steroid hormone. d. Amino acid. e. Polypeptide hormones. Passive Transport Factors affecting rate of diffusion: J = P A (CA-CB) J = net rate of diffusion P= Permeability A= Surface area for diffusion CA = Concentration of substance in solution A CB = Concentration of substance in solution B Rate of diffusion is directly proportional permeability Surface area Concentration gradient Passive Transport Factors affecting rate of diffusion: P=KD/X P= Permeability. K= Partition coefficient. D = Diffusion coefficient. X = thickness of the membrane. Factors affecting permeability - (1)Partition (3)Thickness coefficient. of the (2) Diffusion membrane coefficent -  Partition coefficient (K) Is the ratio between solubility of substance in oil and its solubility in water K= solubility in oil/ solubility in water Lipid soluble substance has high partition coefficient, high permeability and high rate of diffusion  Diffusion coefficient (D) It is best expressed by Stockes –Einstein equation  Diffusion coefficient (D) Is inversely correlated with molecular size pf substance and viscosity of the medium. Large solutes in highly viscous medium has low diffusion coefficient and less permeability.  Diffusion coefficient (D) It could be expressed by Fick's low Question: Which of the following substance that has the highest partition coefficient: a. polypeptide hormone. b. O2. c. CO2. d. Amino acid. e. Na. Passive transport filtration it is passage of water from high concentration of water to low concentration of water through capillary membrane. Passive transport filtration It is passage of water from area with high hydrostatic pressure to area with low hydrostatic pressure through capillary membrane. Question: Which of the following force that is responsible for filtration: a. Kinetic energy. b. Osmotic pressure. c. Colloidal pressure. d. Hydrostatic pressure. e. Oncotic pressure. Passive transport SOLVENT DRAG It is the diffusion of a solute following the diffusion of its solvent through the membrane, i.e. the solvent drags the solute after it. Passive transport SOLVENT DRAG This occurs in the renal tubules where there is absorption of large amounts of water through tight junction. Water drags some urea to be reabsorbed with it. Question: Define solvent drag and give one example?  Summary  Transport is a vital biological process.  There are tow types of transport : active and passive  Passive transport are five types.  Facilitated diffusion is aided transport and has transport maximum.  There are many factors that affect rate of diffusion. 60 60  References  Linda S. Costanzo: physiology, six edition, ELSEVER.  Linda S. Costanzo: BRS physiology, seventh edition, Lippincott Williams & Wilkins.  Lecture notes. 11/18/2024 HBF - 102 61 61