BIOLOGY 3U03 Chapter 5: 5. Acid Base Balance
4 Feb 2017
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Maintained at a low level: variation varies only one millionth as much as na, also regulated at much lower concentrations than sodium. Acids: h+ donor (hcl, h2co3 carbonic acid) Most acids and bases involved in normal acid-base regulation in ecf are weak: do(cid:374)"t full(cid:455) disso(cid:272)iate high proportion remains in undissociated state. Ph = log (1/[h+]) = -log[h+] inversely related to h+ concentration. Blood concentration of h = 40 +- 4eg/l: therefore a normal ph of 7. 4. Cells are metabolising producing co2 and cell potential is (cid:374)egati(cid:448)e i(cid:374) respe(cid:272)t to (cid:449)hat"s outside - favors accumulation of cations (h) favoring a slightly more acidic ph. Focus on ecf ph normal arterial blood plasma pha ~ 7. 4. Icf (cytoplasmic ph ~ 7. 00) depnds critically on ecf ph ~ 7. 40. Act to minimize changes in free [h+] and [oh-: protein system (hemoglobin [hb], plasma proteins) Oh- + hpr h2o + pr: co2/hco3.
