Lab 1 Transport Across Cell Membrane PDF 2024/2025

Faculty of Medicine Academic Year: 2024/2025 Year: 1 Semester:1 Module: HUMAN BODY FUNCTION (HBF-102)  Transport Across the Cell Membrane By: Naema gomaa transport Across the Cell Membrane...

Faculty of Medicine Academic Year: 2024/2025 Year: 1 Semester:1 Module: HUMAN BODY FUNCTION (HBF-102)  Transport Across the Cell Membrane By: Naema gomaa transport Across the Cell Membrane Department: physiology 23 December 2024 Module: HBF-102 2  OBJECTIVES Differentiate between the types of transport across cell membrane. list the different types of channels. Identify the different types of carriers. Mention how macromolecules can cross cell membrane Define the term osmosis and osmotic pressure. Recognize the different 23 December 2024 types of channels Module: HBF-102 3  INTRODUCTION Transport across cell membrane is either passive transport or active transport. Passive means that it doesn't need energy for transport while active means that it needs energy. Passive transport is of two types simple diffusion or facilitated diffusion Active transport is either primary or secondary. 23 December 2024 Module: HBF-102 4  Differentiate between passive and active transport across cell membrane 23 December 2024 Module: HBF-102 5  Simple diffusion It is passive transport , doesn't need energy It doesn't need carrier. particles moves according to their concentration gradient Downhill transport, from high concentration to low concentration. It is affected by Fick's law of diffusion 23 December 2024 Module: HBF-102 6  Fick’s law of diffusion Diffusion Fick’s law of diffusion: coefficient Diffusion rate (amount of the substance moved/unit time) Solubility of the permeability coefficient X Conc. gradient X surface area substance = ------------------------------------------------------------------------------- DC  ----------------------- Thickness of membrane ----------------------  Molecular weight Increase temperature increase the rate of diffusion 23 December 2024 Module: HBF-102 7  Demonstrate diffusion in fluids and the effect of temperature on its Procedure: rate 1- Place several crystals of methylene blue in three beakers containing water that is cold (5oC), at room temperature (25oC) and hot (50oC) respectively. 2-Record the time required for the dye to become evenly dispersed 23 throughout December 2024 the beakers Module: HBF-102 8  Can charged molecules pass easily through cell membrane? Their diffusion is extremely low due to: The formation of hydrated ions with water, which have large size. The interaction between their charges and the charges on the cell membrane 23 December 2024 Module: HBF-102 9  2- Ion channels These are important ways for diffusion of ions Ions move by simple diffusion according to their electrochemical gradient leakage, voltage-gated and ligand-gated channels 23 December 2024 Module: HBF-102 10  1- leakage channels These are watery pathway through integral protein part of cell membrane They are tubed shape extending from ECF to ICF They are highly selective channels. Example: Na leakage channels and K leakage 23 December 2024 Module: HBF-102 11  Q3: Can you explain the direction of movement of ions in each channel? 23 December 2024 Module: HBF-102 12  Answer Ions moves according to its electrochemical gradient Sodium is the chief ECF cation, inside of the cell is negative compared to the outside Potassium ion is the chief intracelullar cation, 23 December 2024 so it Module: HBF-102 13  Gated channels They have gates that can open or close to various signals A- ligand gated channels : they open or close by binding certain ligand substance like neurotransmitter acetyl choline Example : Na ligand gated channels B- Voltage gated channels : they open or close by alteration of membrane electrical potential Example : Na voltage gated channels and K voltage gated channels 23 December 2024 Module: HBF-102 14  : Deduce the role of sodium channels in the mechanism of action of local anesthetics 23 December 2024 Module: HBF-102 15  Answer local anesthetics bind to voltage gated Na channels Block entry of Na to inside of the cell No generation and conduction of action potential (no pain sensation) 23 December 2024 Module: HBF-102 16  3- Facilitated diffusion It is a passive transport that follows the concentration gradient It doesn't need energy It depends on carrier protein It has a transport maximum Example ; transport of glucose 23 December 2024 Module: HBF-102 17  Transport maximum Transport maximum is the Maximal rate at which they can transport a particular solute. It depends on the number of carriers Number of carriers is affected by hormones Diabetes milletus ; decrease in glucose carriers Insulin increase the number of glucose 23 December 2024 carrier Module: HBF-102 18  Q6: From the following diagram, name the 2 different types of transport B A 23 December 2024 Module: HBF-102 19  Answer Figure A: Simple diffusion Particles diffuse directly through the cell membrane From the high concentration to the low concentration No carrier 23 December 2024 Module: HBF-102 20  Answer Figure B: Facilitated diffusion  Particles diffuse through the cell membrane using a carrier  From the high concentration to the low concentration  No energy used 21 23 December 2024 Module: HBF-102  Active transport Solutes move against concentration gradient. Needs energy. Needs carrier protein. Types : primary active transport and secondary active transport 23 December 2024 Module: HBF-102 22  Primary active transport The carrier has an ATPase activity Uphill transport Primary active Pumps  Na+-K+ pump  Ca+2 pump  H+-K+ pump 23 December 2024 Module: HBF-102 23  Q: What is the name of this carrier? and why? 23 December 2024 Module: HBF-102 24  Answer Sodium potassium pump  It is a carrier that uses ATPase enzyme directly= primary active transporter  This pump pumps sodium ions to the ECF and potassium to ICF (against their concentration 23 December 2024 Module: HBF-102 25  Secondary active  It transport is an active transport Na+-K+ pump Na+  depends on sodium K+ gradient created by sodium potassium pump  It is either cotransport or Na+ counter-transport. K+ 23 December 2024 Module: HBF-102 26  Q11 : Explain the difference between the type of transport at A and B B A 23 December 2024 Module: HBF-102 27  Exocytosis It is transport to outside the cell. Fusion of Secretion of secretory vesicle Active process , Secretory vesicle with plasma contents vesicle require energy. membrane Example ; transport of acetyl choline at Nucleus of cell motor end plate 23 December 2024 Module: HBF-102 28  Endocytosis Transport to inside of cell Active process , require energy. Example; phagocytosis of bacteria and dead tissue 23 December 2024 Module: HBF-102 29  Name this type of transport 23 December 2024 Module: HBF-102 30  Osmosis It is passive transport of water across semi-preamble membrane. diffusion of water from area of high concentration water to area of low concentration of water. Or from area of low solute concentration to area of high solute concentration 23 December 2024 Module: HBF-102dif 31  Demonstrate osmosis as a mechanism of transport across the cell membrane Procedure 1- Cut five pieces out of a potato (8 – 10 mm diameter), each measuring about 5 cm long. 2- Determine the volume of each piece by immersing it in a known volume of water in a 20 ml graduate cylinder and noting the volume rise of water in the cylinder. 23 December 2024 Module: HBF-102 32  Osmosis 3- Immerse one piece of the potato in one of the following five solutions: Distilled water, 0.4% NaCl, 0.9% NaCl, 5% NaCl and 10% NaCl. 4- After 2 hours, measure the volume of each piece of potato again and express the changes as a percent of the original volume 23 December 2024 Module: HBF-102 33  Results 23 December 2024 Module: HBF-102 34  Isotonic solutions Solute concentration inside the cell equal to solution outside the cell The amount of water enter the cell equal to amount of water transported outside the cell 23 December 2024 Module: HBF-102 35  Hypotonic solution Solutes concentration inside the cell is higher. Water is transported to inside the cell. Cell swells 23 December 2024 if Module: HBF-102 36  Hypertonic solution Solutes concentration inside the cell is lower. Water is transported to outside the cell. Cell shrinks if exposed to extracellular hypertonicity 23 December 2024 Module: HBF-102 37  Osmotic pressure Osmotic pressure of a solution is the pressure required to applied on the concentrated solution to prevent water movement from diluted side (prevent osmosis ) 23 December 2024 Module: HBF-102 38  References 23 December 2024 Module: HBF-102 39