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ADVANCED PHYSIOLOGY ACID BASE BALANCE

ADVANCED PHYSIOLOGY ACID BASE BALANCE. Instructor Terry Wiseth NORTHLAND COLLEGE. ACID BASE HOMEOSTASIS.

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ADVANCED PHYSIOLOGY ACID BASE BALANCE

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  1. ADVANCED PHYSIOLOGYACID BASE BALANCE InstructorTerry Wiseth NORTHLAND COLLEGE

  2. ACID BASE HOMEOSTASIS • Acid-Base homeostasis involves chemical and physiologic processes responsible for the maintenance of the acidity of body fluids at levels that allow optimal function of the whole individual

  3. ACID BASE HOMEOSTASIS • The chemical processes represent the first line of defense to an acid or base load and include the extracellular and intracellularbuffers • The physiologic processes modulate acid-base composition by changes in cellular metabolism and by adaptive responses in the excretion of volatile acids by the lungs and fixed acids by the kidneys

  4. ACID-BASE HOMEOSTASIS Acids Bases Buffers Acids = Bases Acids < Bases Acids > Bases Acids Acids

  5. ACID BASE HOMEOSTASIS • The need for the existence of multiple mechanisms involved in Acid-Base regulation stems from the critical importance of the hydrogen ion (H+) concentration on the operation of many cellular enzymes and function of vital organs, most prominently the brain and the heart

  6. ACID BASE HOMEOSTASIS • The task imposed on the mechanisms that maintain Acid-Base homeostasis is large • Metabolic pathways are continuously consuming or producing H+ • The daily load of waste products for excretion in the form of volatile and fixed acids is substantial

  7. EFFECTS OF pH • The most general effect of pH changes are on enzyme function • Also affect excitability of nerve and muscle cells pH Excitability pH Excitability

  8. ACID-BASE BALANCE

  9. ACID-BASE BALANCE • Acid - Base balance is primarily concerned with two ions: • Hydrogen (H+) • Bicarbonate (HCO3- ) HCO3- H+

  10. ACID-BASE BALANCE • Derangements of hydrogen and bicarbonate concentrations in body fluids are common in disease processes

  11. ACID-BASE BALANCE • H+ ion has special significance because of the narrow ranges that it must be maintained in order to be compatible with living systems

  12. Normal ACID-BASE BALANCE • Primarily controlled by regulation of H+ ions in the body fluids • Especially extracellular fluids

  13. ACID-BASE REGULATION

  14. ACID-BASE REGULATION • Maintenance of an acceptable pH range in the extracellular fluids is accomplished by three mechanisms: • 1)Chemical Buffers • React very rapidly(less than a second) • 2)Respiratory Regulation • Reacts rapidly (seconds to minutes) • 3)Renal Regulation • Reacts slowly (minutes to hours)

  15. ACID-BASE REGULATION • Chemical Buffers • The body uses pH buffers in the blood to guard against sudden changes in acidity • A pH buffer works chemically to minimize changes in the pH of a solution H+ OH- H+ Buffer OH- OH- H+

  16. ACID-BASE REGULATION • Respiratory Regulation • Carbon dioxide is an important by-product of metabolism and is constantly produced by cells • The blood carries carbon dioxide to the lungs where it is exhaled Cell Metabolism CO2 CO2 CO2 CO2 CO2 CO2

  17. ACID-BASE REGULATION • Respiratory Regulation • When breathing is increased,the blood carbon dioxide leveldecreases and the bloodbecomes more Base • When breathing is decreased,the blood carbon dioxide levelincreases and the blood becomes more Acidic • By adjusting the speed and depth of breathing, the respiratory control centers and lungs are able to regulate the blood pH minute by minute

  18. ACID-BASE REGULATION • Kidney Regulation • Excess acid is excreted by the kidneys, largely in the form of ammonia • The kidneys have some ability to alter the amount of acid or base that is excreted, but this generally takes several days

  19. ACID-BASE REGULATION • Enzymes, hormones and ion distribution are all affected by Hydrogen ion concentrations

  20. ACIDS

  21. ACIDS • Acids can be defined as a proton (H+) donor • Hydrogen containing substances which dissociate in solution to release H+ Click Here

  22. ACIDS • Acids can be defined as a proton (H+) donor • Hydrogen containing substances which dissociate in solution to release H+ Click Here

  23. OH- OH- OH- OH- ACIDS • Acids can be defined as a proton (H+) donor • Hydrogen containing substances which dissociate in solution to release H+ H+ H+ H+ H+

  24. OH- OH- OH- OH- ACIDS • Many other substance (carbohydrates) also contain hydrogen but they are not classified as acids because the hydrogen is tightly bound within their molecular structure and it is never liberated as free H+ H+ H+ H+ H+

  25. ACIDS • Physiologically important acids include: • Carbonic acid (H2CO3) • Phosphoric acid (H3PO4) • Pyruvic acid (C3H4O3) • Lactic acid (C3H6O3) • These acids are dissolved in body fluids Phosphoric acid Lactic acid Pyruvic acid Carbonic acid

  26. BASES

  27. BASES • Bases can be defined as: • A proton (H+) acceptor • Molecules capable of accepting a hydrogen ion (OH-) Click Here

  28. BASES • Bases can be defined as: • A proton (H+) acceptor • Molecules capable of accepting a hydrogen ion (OH-) Click Here

  29. OH- OH- OH- OH- BASES • Bases can be defined as: • A proton (H+) acceptor • Molecules capable of accepting a hydroxide ion (OH-) H+ H+ H+ H+

  30. BASES • Physiologically important bases include: • Bicarbonate (HCO3- ) • Biphosphate (HPO4-2 ) Biphosphate Bicarbonate

  31. pH SCALE

  32. pH SCALE • pH refers to Potential Hydrogen • Expresses hydrogen ion concentration in water solutions • Water ionizes to a limited extent to form equal amounts of H+ ions and OH- ions • H2OH+ + OH- • H+ion is an acid • OH-ion is a base

  33. pH SCALE • H+ion is an acid

  34. pH SCALE • OH-ion is a base

  35. pH SCALE • H+ion is an acid • OH- ion is a base

  36. H+ H+ OH- H+ OH- OH- H+ H+ OH- H+ H+ H+ H+ OH- OH- H+ OH- H+ OH- H+ H+ OH- OH- OH- H+ OH- H+ OH- OH- pH SCALE • Pure water is Neutral • ( H+ = OH-) • pH = 7 • Acid • ( H+ > OH- ) • pH < 7 • Base • ( H+< OH-) • pH > 7 • Normal blood pH is 7.35 - 7.45 • pH range compatible with life is 6.8 - 8.0 ACIDS, BASES OR NEUTRAL??? 3 1 2

  37. pH SCALE • pH equals the logarithm (log) to the base 10 of the reciprocal of the hydrogen ion (H+) concentration • H+ concentration in extracellular fluid (ECF) pH = log 1 / H+ concentration 4 X 10 -8 (0.00000004)

  38. pH SCALE • Low pH values = high H+ concentrations • H+ concentration in denominator of formula • Unit changes in pH represent a tenfold change in H+ concentrations • Nature of logarithms pH = log 1 / H+ concentration 4 X 10 -8 (0.00000004)

  39. pH SCALE • pH = 4 is more acidic than pH = 6 • pH = 4 has 10 times more free H+ concentration than pH = 5 and 100 times more free H+ concentration than pH = 6 NORMAL ACIDOSIS ALKALOSIS DEATH DEATH 6.8 7.3 7.4 7.5 8.0 Venous Blood Arterial Blood

  40. pH SCALE

  41. pH SCALE

  42. ACIDOSIS / ALKALOSIS

  43. ACIDOSIS / ALKALOSIS • An abnormality in one or more of the pH control mechanisms can cause one of two major disturbances in Acid-Base balance • Acidosis • Alkalosis

  44. ACIDOSIS / ALKALOSIS • Acidosis • A condition in which the blood has too much acid (or too little base), frequently resulting in a decrease in blood pH • Alkalosis • A condition in which the blood has too much base (or too little acid), occasionally resulting in an increase in blood pH

  45. ACIDOSIS / ALKALOSIS • Acidosis and alkalosis are not diseases but rather are the results of a wide variety of disorders • The presence ofacidosis oralkalosis providesan important clueto physicians thata seriousmetabolicproblem exists

  46. ACIDOSIS / ALKALOSIS • pH changes have dramatic effects on normal cell function • 1) Changes in excitability of nerve and muscle cells • 2) Influences enzyme activity • 3) Influences K+ levels

  47. CHANGES IN CELL EXCITABILITY • pH decrease (more acidic) depresses the central nervous system • Can lead to loss of consciousness • pH increase (more basic) can cause over-excitability • Tingling sensations, nervousness, muscle twitches

  48. INFLUENCES ON ENZYME ACTIVITY • pH increases or decreases can alter the shape of the enzyme rendering it non-functional • Changes in enzyme structure can result in accelerated or depressed metabolic actions within the cell

  49. INFLUENCES ON K+ LEVELS • When reabsorbing Na+ from the filtrate of the renal tubules K+ or H+ is secreted (exchanged) • Normally K+ issecreted in muchgreater amountsthan H+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ H+ K+

  50. INFLUENCES ON K+ LEVELS • If H+ concentrations are high (acidosis) than H+ is secreted in greater amounts • This leaves less K+ than usual excreted • The resultant K+ retention can affect cardiac function and other systems K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ H+ H+ H+ H+ H+ H+ H+

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