27_LectureOutline

27_LectureOutline - Introduction Water Is 99% of fluid...

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Introduction Water Is 99% of fluid outside cells (extracellular fluid) Is an essential ingredient of cytosol (intracellular fluid) All cellular operations rely on water As a diffusion medium for gases, nutrients, and waste products Fluid, Electrolyte, and Acid–Base Balance The body must maintain normal volume and composition of Extracellular fluid (ECF) Fluid Balance Is a daily balance between Amount of water gained Amount of water lost to environment Involves regulating content and distribution of body water in ECF and ICF The Digestive System Is the primary source of water gains Plus a small amount from metabolic activity The Urinary System Is the primary route of water loss Are ions released through dissociation of inorganic compounds Can conduct electrical current in solution Electrolyte balance When the gains and losses of all electrolytes are equal Primarily involves balancing rates of absorption across digestive tract with rates of loss at kidneys and sweat glands Acid–Base Balance Precisely balances production and loss of hydrogen ions (pH) The body generates acids during normal metabolism Tends to reduce pH The Kidneys Secrete hydrogen ions into urine Generate buffers that enter bloodstream In distal segments of distal convoluted tubule (DCT) and collecting system
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The Lungs Affect pH balance through elimination of carbon dioxide Fluid Compartments Water Accounts for Roughly 60% percent of male body weight 50% percent of female body weight Mostly in intracellular fluid Water Exchange Water exchange between ICF and ECF occurs across plasma membranes by Osmosis Diffusion Carrier-mediated transport Major Subdivisions of ECF Interstitial fluid of peripheral tissues Plasma of circulating blood Minor Subdivisions of ECF Lymph, perilymph, and endolymph Cerebrospinal fluid (CSF) Synovial fluid Serous fluids (pleural, pericardial, and peritoneal) Aqueous humor Exchange among Subdivisions of ECF Occurs primarily across endothelial lining of capillaries From interstitial spaces to plasma Through lymphatic vessels that drain into the venous system ECF: Solute Content Types and amounts vary regionally Electrolytes Proteins Nutrients Waste products The ECF and the ICF Are called fluid compartments because they behave as distinct entities Are separated by plasma membranes and active transport
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Cations and Anions In ECF Sodium, chloride, and bicarbonate In ICF Potassium, magnesium, and phosphate ions Negatively charged proteins Membrane Functions Plasma membranes are selectively permeable Ions enter or leave via specific membrane channels Carrier mechanisms move specific ions in or out of cell The Osmotic Concentration of ICF and ECF Is identical Osmosis eliminates minor differences in concentration
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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27_LectureOutline - Introduction Water Is 99% of fluid...

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