Biochem p h of blood(may.13.2010)

1. pH of BLOOD , ITS REGULATION, ACIDOSIS & ALKALOSIS . MAY.13.2010

2. BASICS Acid-base balance is a dynamic relationship which reflects the concentration of hydrogen ions (H + ) in the body. Hydrogen ions are acids which must be maintained within strict limits Any deviation from the norm affects biochemical events. Acid-base relationship is measured in a logarithm (pH) which is inversely proportional to the hydrogen ion concentration.

3. pH ( power of H ) pH = Negative log 10 of the hydrogen ions concentration expressed in mol/L pH= - log 10 [H + ] High H + ion concentration = low pH Low H + ion concentration = high pH BASICS

4. THE pH SCALE Scale ranges from 1 to 14 1 means only hydrogen ions are present 14 means no hydrogen ions present The pH of water is 7.0 which is neutral The normal range of the human body is 7.35 - 7.45

5. Basic pH neutral Acidic Death Normal and abnormal pH ranges of blood pH’s of common substances Death Acidosis Normal Alkalosis 8.00 7.45 7.35 6.8 Battery acid Concentrated lye Water Gastric juice Lemon juice Vinegar Household ammonia Baking soda Pancreatic juice Blood Milk Urine Coffee Orange juice 14 13 12 11 10 9 8 7 6 5 4 3 2 1

6. pH OF BLOOD [7.35-7.45] Alteration outside these boundaries affects all body systems Can result in coma, cardiac failure, and circulatory collapse. Normal pH of body fluids Arterial blood is 7.4 Venous blood and interstitial fluid is 7.35 Intracellular fluid is 7.0 Alkalosis or alkalemia – arterial blood pH rises above 7.45 Acidosis or acidemia – arterial pH drops below 7.35

7. ACID AND BASES ACID : Protons (hydrogen ions H + ) donors . BASES : Protons (hydrogen ions H + ) acceptors . (Cation= positive, Anion=negative)

8. Weak acid : Partially dissociate. ( not completely break apart ) Strong acid : completely dissociate into anions and cation. STRONG AND WEAK ACID

9. ACID Strong Acid Sulfuric acid Weak acid Carbonic acid Lactic acid Pyruvic acid Citric acid Acetatoacetic acid β -hydroxybutyric acid Acetic acid Dihydrogen Phosphate Ammonium ion MAJOR SOURCES Dietary sulfate and S-containing amino acids. (Cystine, Methionine.) CO2 from TCA cycle Anaerobic glycolysis Glycolysis TCA cycle and diet(e.g., citric fruits) Fatty acid oxidation to ketone bodies Fatty acid oxidation to ketone bodies Ethanol metabolism Dietary organic phosphates Dietary nitrogen-containing compounds ACID IN THE BODY OF A HEALTHY INDIVIDUAL

10. SOURCES OF HYDROGEN IONS Most hydrogen ions originate from cellular metabolism. Breakdown of phosphorus-containing proteins releases phosphoric acid into the ECF. Anaerobic respiration of glucose produces lactic acid . Fat metabolism yields organic acids and ketone bodies . Transporting carbon dioxide as bicarbonate releases hydrogen ions.

11. BODY REGULATION OF ACID-BASE

12. The body constantly produces acids through metabolism. These acids must be constantly eliminated from the body. Three systems perform this task Buffer system Respiratory system Renal system

13. BUFFER SYSTEMS IN BODY FLUIDS

14. BUFFER SYSTEM Buffers: if pH rises, buffers bind H + ; if pH falls, buffers release H + Protein buffer : Intracellular and plasma proteins absorb H + . Provide ¾ of buffering in body. E.g., hemoglobin. Bicarbonate buffering system : Important in plasma Phosphate buffer system : important as an intracellular buffer The fastest performer, works in seconds. Bicarbonate ions combine with excess hydrogen ions to form carbonic acid in a dynamic relationship.

15. THE CARBONIC ACID-BICARBONATE BUFFER SYSTEM

16. CARBONIC ACID-BICARBONATE BUFFER SYSTEM IN REGULATIOIN OF pH

17. THE CENTRAL ROLE OF CARBONIC ACID-BICARBONATE SYSTEM IN REGULATION OF pH

18. AMINO ACID BUFFER

19. For every molecule of carbonic acid, there are 20 molecules of bicarbonate. Any change in the this 20:1 ratio is immediately corrected to maintain pH. An increase H + causes an increase in H 2 CO 3 . A decrease in H + causes a decrease in H 2 CO 3 . BUFFER SYSTEM

20. Carbonic acid is a weak, volatile acid which must be eliminated. The enzyme carbonic anhydrase causes the carbonic acid to convert to carbon dioxide and water. The CO 2 and the H 2 O are easily eliminated by the lungs and kidneys. The system also works in reverse. BUFFER SYSTEM

21. RESPIRATORY SYSTEM Works in minutes The lungs eliminate excess CO 2 by increasing respirations, causing a decrease in H + and an increase in pH. The lungs can retain more CO 2 by slowing respirations, causing an increase in H + and a decrease in pH. Respiratory center: if pH rises, respiratory rate decreases; if pH falls, respiratory rate increases. A C I D- acid- increase Al kali- alkali-lower

22. RESPIRATORY ACID-BASE REGULATION

23. RESPIRATORY ACID-BASE REGULATION

24. RENAL SYSTEM Can take hours to days to work Kidneys can retain bicarbonate ion, causing a decrease in H + and an increase in pH Kidneys can excrete bicarbonate ion, causing an increase in H + and a decrease in pH. Kidneys if pH rises, distal tubule decreases H + secretion into the urine and decreases HCO 3 - absorption into the blood (more H 2 CO 3 will dissociate into H + and HCO 3 - ); if pH falls, distal tubule increases H + secretion into the urine and increases HCO 3 - absorption into the blood

25. KIDNEY TUBULES AND pH REGULATION

26. KIDNEY TUBULES AND pH REGULATION

27. ACID-BASE DISORDERS

28. Respiratory acid base disorders Result when abnormal respiratory function causes rise or fall in CO 2 in ECF Metabolic acid-base disorders Generation of organic or fixed acids Anything affecting concentration of bicarbonate ions in ECF ACID-BASE DISORDERS

29. ACIDOSIS AND ALKALOSIS Acidosis : pH body fluids below 7.35 Respiratory: Caused by inadequate ventilation- reduced elimination of CO 2 , asthma, damage to respiratory center in brain, emphysema. Metabolic: Results from all conditions other than respiratory that decrease pH- diarrhea, vomiting, ingesting overdose of aspirin, untreated diabetes mellitus, anaerobic respiration. Alkalosis : pH body fluids above 7.45 Respiratory: Caused by hyperventilation, high altitude (reduced partial pressure of O 2 ) Metabolic: Results from all conditions other than respiratory that increase pH- severe vomiting, too much aldosterone, ingestion of substances like bicarbonate of soda.

30. Results from excessive levels of CO 2 in body fluids. RESPIRATORY ACIDOSIS

31. Relatively rare condition Associated with hyperventilation RESPIRATORY ALKALOSIS

32. Major causes are: Depletion of bicarbonate reserve Inability to excrete hydrogen ions at kidneys Production of large numbers of fixed / organic acids Bicarbonate loss due to chronic diarrhea METOBOLIC ACIDOSIS

33. Occurs when HCO 3 - concentrations become elevated Caused by repeated vomiting. METOBOLIC ALKALOSIS

34. THE RESPONSE TO METABOLIC ACIDOSIS

35. THE RESPONSE TO METABOLIC ALKALOSIS

36. ACID-BASE AND POTASSIUM IMBALANCE Acidosis H + diffuses into cells and drives out K + , elevating K + concentration in ECF H + buffered by protein in ICF, causes membrane hyperpolarization, nerve and muscle cells are hard to stimulate; CNS depression may lead to death Acidosis Hyperkalemia

37. Alkalosis H + diffuses out of cells and K + diffuses in, membranes depolarized, nerves over-stimulate muscles causing spasms, tetany, convulsions, respiratory paralysis ACID-BASE AND POTASSIUM IMBALANCE Alkalosis Hypokalemia

38. Diagnostic blood tests (Arterial Blood Gases) ABG Blood pH P CO2 Bicarbonate levels DETECTION OF ACIDOSIS AND ALKALOSIS

39. INCREASED IN BLOOD pH

40. DECREASED IN BLOOD pH

41. POINTS TO REMEMBER pH= - log 10 [H + ] High H+ ion concentration = low pH Low H+ ion concentration = high pH Normal pH OF BLOOD [7.35-7.45] Regulation of acid-base balance by 3 systems. Acid-base disorders. Regulation of acidosis and alkalosis.

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