HCO3 pk=61 a Present in large quantities. a Open system Respiratory and renal systems act on this buffer system. Most important ECF buffer
HCO3 - ◼ pk. = 6.1. ◼ Present in large quantities. ◼ Open system. ◼ Respiratory and renal systems act on this buffer system. ◼ Most important ECF buffer
HCO, Limitations Cannot protect ECF from respiratory problems. Cannot protect ECF from elevated or decreased co2 Limited by availability of HCO3
HCO3 - Limitations ◼ Cannot protect ECF from respiratory problems. ◼ Cannot protect ECF from elevated or decreased CO2 . ◼ Limited by availability of HCO3 -
Phosphates pk, = 6.8. Low concentration in ECF better buffer in ICF, kidneys, and bone
Phosphates ◼ pk. = 6.8. ◼ Low concentration in ECF, better buffer in ICF, kidneys, and bone
Respiratory system 2nd line of defense Acts within min -maximal in 12-24 rs H2 CO3 produced converted to coal and excreted by the lungs. Alveolar ventilation also increases as pH decreases(rate and depth) Coarse, CAnNot eliminate fixed acid
Respiratory System ◼ 2nd line of defense. ◼ Acts within min. -maximal in 12-24 hrs. ◼ H2CO3 produced converted to CO2 , and excreted by the lungs. ◼ Alveolar ventilation also increases as pH decreases (rate and depth). ◼ Coarse , CANNOT eliminate fixed acid
Urinary Buffers Nephron cannot produce urine at pH≤45. in order to excrete more h+ the acid must be buffered H+ secreted into the urine tubule and combines with hpo 2- or nh HPo42+H+—H2Po4 NH3+H+—NH4+
Urinary Buffers ◼ Nephron cannot produce urine at pH < 4.5. ◼ IN order to excrete more H+, the acid must be buffered. ◼ H+ secreted into the urine tubule and combines with HPO4 2- or NH3 . ◼ HPO4 2- + H+ H2PO4 - ◼ NH3 + H+ NH4 +