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Transcript
Chapter 5 Membrane Dynamics Outline Cell Membranes Movement across membranes Distribution of water and solutes in the body Osmosis Lab Proteins: role in communication Proteins act as “passageways” Channel Proteins Open Gated* Carrier Proteins Open and Gated Channels Normally closed Normally open These are types of “gates” Chemical gates Voltage gates Mechanical gates Gated channels almost always closed Cystic Fibrosis Trans-membrane Receptor CF: autosomal recessive CFTR mutation Blocks Cl- Carrier Proteins Like a revolving door! Movement across membranes I. Passive transport: no ATP Non-carrier mediated Carrier mediated Diffusion: passive Without membrane Passive diffusion Across membrane: no carrier Passive transport Passive movement can require a carrier Specific Can saturate II. Active Transport Active Transport Requires a TRANSPORTER AND Requires ENERGY Primary Active Transport Is this a symport or antiport? Let’s look at both primary and secondary together! NOTICE Na+ gradient is potential energy Figure 5-28 (insert) Distribution of water and solutes in the body Osmosis Movement of water across a semi-permeable membrane Compare osmolarity of one solution to another solution. Isosmotic Hyperosmotic Hyposmotic Number of particles are A B Term Used Particle # Particle # 300 300 A & B are Isomotic #>300 300 A Hyperosmotic to B #<300 300 A Hyposmotic to B A A B B Now, look at the following terms Isotonic Hypotonic Hypertonic Tonicity defines what a solution would do to the cell volume (size). To cell size and tonicity: You must understand the terms But I’m so tired… Non-penetrating versus Penetrating solutes 3 Beakers with various concentrations of nonpenetrating solutes and RBCs Here’s your experiment: 600 mOsm You place red blood cells in the three Beakers and view them later under the microscope. Now what will you observ 300 mOsm 200 mOsm Tonicity defines the affect on cell size or shape. Crenation No change Swelling Hypertonic 600 mOsm Isotonic 300 mOsm Hypotonic 200 mOsm Non Penetrating What if… A cell of 6 Osm is placed in a solution also of 6 Osm then what is the tonicity? Oops, that’s tricky! There is no way to know the tonicity with the information given! Why?? Look and penetrating versus non-penetrating But what eventually happens to H20? Clinical Application Physio A. 0.9% saline SMC A. 0.9% saline: is isosmotic and isotonic 0.9% saline is non penetrating= 300 mOsm Transport of Macromolecules Transport of Macromolecules White blood cells Phagocytosis Receptor-Mediated Endocytosis all cells can carry out endocytosis Transport errors… Membrane Potential Cell charge and cell function are related The cell membrane separates charges Measurement of this charge What ions may cause this charge? Nernst Equation: You can calculate this answer. Eion= 61/z log [ion]out/[ion]in 61 is a constant Z is charge of ion Ion ICF K+ mM 150 Na+ mM 15 ECF 5 150 Now let’s now integrate the concept of cell membranes and a physiological process… Cell function and Charge