pH 0.0 / 5 ? OtherPhysiology/BiochemistryUniversityNone Created by: Jennifer WelshCreated on: 25-02-15 17:36 What does the pH scale measure? Hydrogen ion concentration 1 of 29 Why does pH need to be regulated? Adding/removing H+ from proteins causes conformational change (denaturation) and effects the functioning of enzymes which can be irreversible 2 of 29 What is the maximum tolerated range of pH? 6.8-7.8 3 of 29 What are the typical mammalian pH values in extracellular fluid? 7.36-7.44 4 of 29 What are the typical mammalian pH values in intracellular fluid? 7.10-7.20 5 of 29 What is a conjugate acid? A base that will accept a proton 6 of 29 Define a weak acid/alkali It doesn't dissociate fully in solution 7 of 29 Where do H+ come from in body fluids? Volatile acids derived from CO2 and non volatile acids produced during metabolism eg phosphoric acid and lactic acid 8 of 29 Carnivores are net _______ producers acid 9 of 29 What are carbohydrates and fats broken down to? CO2 and H2O 10 of 29 What are proteins broken down to? HCl and H2SO4 or HCO3- 11 of 29 What are organic anions broken down to? HCO3- 12 of 29 How can H+ concentration be regulated? Buffer systems in the body, respiratory centres respond to changes in H+ concentration (mins) and kidneys can adjust [H+] (hours) 13 of 29 What do buffers do? They minimise the change in pH when acid or base is added 14 of 29 What are amphoteric buffers? These accept or donate protons 15 of 29 How can we predict changes in pH? pH=pK + log[base]/[acid] 16 of 29 When do buffers work best? When pH=pK as changes in [H+] do not have much effect on pH 17 of 29 What buffering systems are in the body? Dilution in whole body water, buffering in blood, buffers in ECF, ICF buffers, carbonate in bone and ion exchange in bone 18 of 29 What buffers are in the blood? HCO3-, haemoglobin and inorganic phosphates 19 of 29 What buffers are in ECF? Mostly HCO3- 20 of 29 What buffers are in ICF? Protein, inorganic phosphate and organic phosphate 21 of 29 Why is carbonate in bone a buffer? Contributes HCO3- to plasma and ECF 22 of 29 How does ion exchange in bone act as a buffer? H+ exchanged for Na+, Ca2+, K+ and Mg2+ 23 of 29 How do kidneys control [H+] in ECF? They produce acid or alkaline urine 24 of 29 What urinary buffers are there? Inorganic phosphate and ammonia/ammonium (they act to attenuate pH changes in urine and allow the excretion of more H+) 25 of 29 Name some inorganic phosphates Na2HPO4 (alkaline) and NaH2PO4 (acid) 26 of 29 What type of homeostatic mechanisms are there for pH? Compensation and correction 27 of 29 Define compensation Rapid, short term pH regulation 28 of 29 Define correction Longer term, retuning HCO3- and pCO2 to normal levels 29 of 29
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