Can restore normal pH FAST milliseconds Buffer system composed of weak acid and

Can restore normal ph fast milliseconds buffer system

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Can restore normal pH FAST - milliseconds Buffer system composed of weak acid and weak base 3 major chemical buffers in the body: Bicarbonate system Phosphate system Protein system The amount of acid or base neutralized depends on concentration of buffer and pH of working environment
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24-58 Bicarbonate Buffer System a solution of carbonic acid and bicarbonate ions Carbonic acid and bicarbonate ions participate in a reversible reaction CO 2 + H 2 O H 2 CO 3 HCO 3 + H + Direction of reaction determines whether it raises or lowers pH CO 2 + H 2 O H 2 CO 3 HCO 3 + H + Lowers pH by releasing H + CO 2 + H 2 O H 2 CO 3 HCO 3 + H + Raises pH by binding H + integrated with lungs & kidneys to regulate pH and CO 2 - to lower pH, kidneys excrete HCO 3 & lungs retain CO 2 - to raise pH, kidneys excrete H + & lungs excrete CO 2
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24-59 Phosphate Buffer system a solution of HPO 4 2− and H 2 PO 4 H 2 PO 4 HPO 4 2− + H + Reactions that proceed to the right liberate H + and pH, and reactions that proceed to the left will pH Phosphates are important buffers in ICF and renal tubules Protein Buffer System Proteins , more concentrated than bicarbonate or phosphate systems, especially in the ICF accounts for ~3/4 all chemical buffering in body fluids Protein buffering ability due to side groups of amino acid residues pH carboxyl (−COOH) groups release H + when pH gets too low, amino (−NH 2 ) groups bind H
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24-60 Respiratory Control of pH Strong buffering capacity due to bicarbonate buffer system CO 2 + H 2 O   H 2 CO 3 HCO 3 - + H + addition of CO 2 to body fluids H + , lowering pH removal of CO 2 H + , raising pH Respiratory system neutralizes 2-3X more acid v. chemical buffers Chapter 22 ... CO 2 is constantly produced by aerobic metabolism, and normally eliminated by the lungs at an equivalent rate CO 2 and pH stimulate pulmonary ventilation, whereas pH inhibits pulmonary ventilation CO 2 from metabolism + H 2 O H 2 CO 3 HCO 3 + H + Lowers pH by 'releasing' H + CO 2 expired + H 2 O H 2 CO 3 HCO 3 + H + Raises pH by 'binding' H +
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24-61 Renal Control of pH Kidneys neutralize more acid or base than either the respiratory system or chemical buffers Renal tubules secrete H + into tubular fluid & excrete Most H + binds to bicarbonate, ammonia, and phosphate buffers Bound and free H + excreted in urine, i.e., H + expelled from body Other buffer systems H + concentration by binding H +
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Secretion and Neutralization of H + by the Kidney K + Na + NaHCO 3 HCO 3 Na + Urine Carbonic Anhydras e CO 2 Aerobic Respiration Na + HCO 3 + CO 2 H 2 CO 3 H 2 CO 3 H 2 O Antiport Diffusion thru channel Diffusion thru lipid membrane Key + CO 2 2 1 8 5 10 11 6 7 9 4 3 1 In blood: H + + HCO 3 H 2 CO 3 2 H 2 CO 3 H 2 O + CO 2 , which enter the tubule cell 3 4 Carbonic Anhydrase combines H 2 O + CO 2 to re-form H 2 CO 3 5 H 2 CO 3 HCO 3 + H + ; HCO 3 returns to blood 6 Na + -H + antiport exchanges H + for Na + 7 from glomerular filtrate NaHCO 3 Na + + HCO 3 ; Na + transported into tubule cell 8 Na + leaves cells by Na + -pump at basolateral side into blood 9 HCO 3 + H + from tubule H 2 CO 3 10 At brushborder, H 2 CO 3 H 2 O + CO 2
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