filtrate for elimination in urine bicarbonate ions HCO3 are transported to

Filtrate for elimination in urine bicarbonate ions

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filtrate for elimination in urine - bicarbonate ions (HCO3-) are transported to interstitial fluid & then into the blood ** see figure 25.10: production of bicarbonate ions from glutamine in the proximal tubule - hydrogen ion secretion in distal tubule & collecting system major acidification of urine occurs in late distal tubule collecting system hydrogen ions are actively transported into the filtrate by intercalated cells - 1. CO2 diffuses from the blood & interstitial fluid into distal tubule cells where t reacts w/ water & forms carbonic acid - 2. carbonic acid dissociates into hydrogen ions & bicarbonate - 3. hydrogen ions are transported into the filtrate for elimination - 4. bicarbonate is transported into the interstitial fluid then blood - ** see figure 25.11: secretion of hydrogen ions in the distal tubule & collecting duct acid-base imbalances: - occurs when compensatory mechanisms are unable to cope w/ additional acids or bases leads to a pH outside the normally maintained narrow range
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body attempts to correct both acidosis & alkalosis through both respiratory & urinary systems - respiratory & urinary compensation - mechanisms are incapable of completely correcting pH change - correction of the underlying root cause is the only way to completely correct with imbalance - acidosis: a body fluid pH <7.35 acidemia refers to low blood pH specifically acidosis develops when more hydrogen ions are adde than the buffer system can bind - or when the # of buffer molecules (such as bicarbonate) decreases causes neurons to become less excitable & leads to signs & symptoms of nervous system depression compensatory mechanisms has the same goal, regardless of the cause - reduce the # of hydrogen ions - increase the # of base ions (especially bicarbonate) - respiratory acidosis & compensation: decrease in pH of body fluids due to excess CO2 caused when ventilation decreases (hypoventioation) - leads to accumulation of CO2 as less gas is exhaled, interfering w/ the carbonic acid- bicarbonate buffer system - leads to a shift that favors production of carbonic acid & a lowering blood pH - general causes are suppressed ventilation from brainstem dysfunction, blockage of air passages in the lungs, & decreased gas exchange in the alveoli respiratory compensation begins within minutes of decreased pH - excess hydrogen ions in ECF stimulate chemoreceptors in the brain that trigger an increase in the rate & depth of ventilation increases the amount of CO2 exhaled, indirectly lowering hydrogen ion concentration renal compensation is more effective than respiratory compensation but can take several hours to days to have an effect - metabolic acidosis & compensation: addition of hydrogen ions to ECF (from acids other than CO2) OR a loss of bicarbonate can be caused by addition of metabolic acids (ketones, uric acid, lactic acid, or methanol) all of which lead to excess hydrogen ions & a drop in pH production of excess metabolic acid can also occur as is the case w/ diabetic ketoacidosis -
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