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Lecture 36
Acid-Base Balance
| Term | Definition |
|---|---|
| Acids | Acids are AH- acids dissolciate into A- and H+ strong acids, like Hcl in the stomach completely dissociate weak acids,like h2co3 carbonic acid,partially dissociate |
| Bases | Bases B,can bind H+ to become BH+. the only sig. physiological base is ammonia,NH3 becomes nh4+. ammonia buffers renal filtrate,allowing more h+ excretion |
| pH | measure of pH in a sol.pH=-log[h+] inc in h+ causes dec in pH.the avg blood pH is 7.40,avg cell pH is about 7.0 blood pH below 7.35 is acidosis,blood pH above 7.45 is alkalosis. acido is far more common than alk.cells will have bigger pH shifts than blood |
| Acidosis Effects | Acidosis depresses the neurons,especially in the CNS.alkalosis makes neurons hyperexcitable.acidosis in general dec enzyme activity,but a few inc acidosis causes inc h+ excretion,and therefore dec k+ excretion inc k+ causes cardiac and neural probs. |
| Sources of H+ | small amounts in food,such as citric acid.most generated in the body:carbonic acid from co2,sulfer and phosphoric acids from proteins,metabolic acids such as lactic acids. |
| Control of H+ | h+ is controlled in 3 ways: chemical buffering,respiratory control of co2,and renal control of h+ excretion. |
| Buffers | different buffers work in diff places.buffers work by binding h+ converting A- into AH. this removes h+ from the solution and from pH.first line of h+ defense. |
| Extracellular Buffering | bicarbonate is the most important ECF buffer. hco3- bind h+ to form h2co3 which dissociates to co2 and h2o. hemoglobin in rbc's buffers h+ produced by co2 inc in venous blood. |
| Intracellular Buffering | proteins in cells bind to h+ in ICF.in some cells, especially muscle cells,phosphate helps buffer ICF. |
| Urine Buffering | phosphate and bicarbonate are dissociated acids that buffer renal filtrate. ammonia is a base that also buffers renal filtrate. |
| Respiratory Control of H+ | second line of h+ defense. works w/ non respiratory sources of h+. inc h+ or inc co2,inc depth and freq of respiration,this reduces co2 in blood,reducing h+ back toward normal. |
| Kidney Control of H+ | third line of h+ defenses.removes h+ from any non renal source in the body |
| H+ Excretion | h+ pumps in the renal tubules secrete h+ into the filtrate. urine pH is normally 6.0 but can be as low as 4.5 |
| Acid-Base Imbalances | pathological changes in the control of h+ result in pH changes.these can be compensated by the respiratory and renal sys. if not of respiratory or renal origin a sys cannot compensate for its own problem:renal probs can require renal compensation. |
| Respiratory Acidosis | abnormal co2 retention by hypoventilation. lung diseases,drugs,nerve/muscle disorders,breath holding. renal compensation by inc h+ secretion |
| Respiratory Alkalosis | dec from hyperventilation. fear/anxiety,asprin poisoning,conscious breathing. dec h+ secretion or removal of condition |
| Metabolic Acidosis | most common acid-base disorder. severe diarrhea,loss of bicarbonate. excess h+ production during fat use in diabetics. exercise leading to lactate and h+ production. kidney failure,cannot excrete h+ or conserve hco3-. |
| Metabolic Alkalosis | dec. in h+ for non-respiratory reasons.vomiting loses h+ in vomitus.excess bicarbonate ingestion.dec respiratory rate and retain h+ in kidneys to compensate. h+ retention inc k+ loss. |
Created by:
danamarie9323
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