BIO%20203.09%20Lecture%205s

BIO%20203.09%20Lecture%205s - BIO 203: Lecture 5 - Water...

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1 BIO 203: Lecture 5 - Water and Ion Balance Prof. William Collins Office: 534 Life Sciences Building Office Hours: Mondays, 9:00 - 10:00 PM (on-line) Tuesdays, 11:30 AM - 12:30 PM Thursdays, 4:00 - 5:00 PM Water and Ion Balance What is the Basic Biological Need: All cells need to exist in an aqueous environment (Basic Principle #1) H 2 Homeostasis, budget Tightly associated with temperature regulation… Evaporative cooling critical to maintaining T B under conditions of high T amb and/or high MR (e.g., during exercise).
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2 Body fluids (BF)--Compartmentalized • Intracellular fluids (ICF ) {hi K + } • Extracellular fluids (ECF ) {hi Na + } Interstitial fluids (IF) Plasma (liquid (non-cellular) portion of blood) • Body Fluid (BF) == ECF Distribution of fluids in the body (human) clump compartments together 60 kg person 20 kg solutes 40 L H 2 O 25 L ICF 15 L ECF 12 L IF 3 L Plasma 2 L RBCs 23 L other cells 5 L Blood
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3 Physical Laws/Concepts - Solutes vs Solvent Solvent: H 2 O - Forms bulk of body composition Solutes: dissolved substances NaCl Na + + Cl - {Ions} Sucrose Sucrose Concentration = # molecules of solute/volume or mass of solvent H 2 O (solvent) NaCl Sucrose Na + Cl - S Solutes Physical Laws/Concepts - Diffusion Diffusion is the movement of a substance from a region of high concentration to a region of low concentration Passive process!! Does not require the input of energy. Random thermal motions (function of temperature) Transport equation (Fick’s law of diffusion (simplest form)) D s : diffusion coefficient - describes how readily the solute moves ( C 2 - C 1 ) : concentration gradient of solute - driving force of diffusion dQ S dt "# D S $ ( C 2 # C 1 )
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4 Physical Laws/Concepts - Diffusion 2 1 C 2 > C 1 Driving force; 2 1 Net diffusion; 2 1 All solutes (including H
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BIO%20203.09%20Lecture%205s - BIO 203: Lecture 5 - Water...

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