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Acid Base Balance Or Homeostasis of Blood Ph Or Regulation of Blood Ph PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "ACID BASE BALANCE OR Homeostasis of Blood pH OR Regulation of Blood pH" by Dr Anissa Atif Mirza.

This medical PowerPoint presentation is about acid-base balance. The human body maintains a delicate balance of acidity and alkalinity, or pH, in the blood and other bodily fluids to ensure proper function. The acid-base balance is critical to many physiological processes, including enzymatic reactions, oxygen transport, and nerve function. The normal pH range for blood is between 7.35 and 7.45.

Several systems in the body work together to regulate blood pH, including the respiratory, renal, and buffering systems.

The respiratory system helps regulate blood pH by controlling the amount of carbon dioxide (CO2) in the blood. Carbon dioxide is a byproduct of cellular respiration and can form carbonic acid in the blood, which can lower the pH. When the pH drops, the respiratory system responds by increasing the rate and depth of breathing, which helps to eliminate excess CO2 from the body and increase the pH.

The renal system also plays a critical role in regulating blood pH. The kidneys can excrete or reabsorb hydrogen ions (H+) and bicarbonate ions (HCO3-) to help maintain the acid-base balance. When the blood becomes too acidic, the kidneys can excrete more H+ ions and reabsorb more HCO3- ions to increase the pH. Conversely, when the blood becomes too alkaline, the kidneys can excrete more HCO3- ions and retain more H+ ions to lower the pH.

The buffering system is a third line of defense against pH changes. Buffers are chemical compounds that can absorb or release H+ ions to help maintain a stable pH. The body has several buffer systems, including the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system.

In summary, the regulation of blood pH is a complex process that involves the respiratory, renal, and buffering systems working together to maintain a delicate balance. Any disruptions to this balance can have serious consequences, such as acidosis or alkalosis, which can affect many bodily functions.

Tags : Homeostasis of Blood pH, Regulation of Blood pH, acid-base balance

Published on : Jun 23, 2023 | Views : 1097 | Downloads : 4

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Slide 1-

ACID BASE BALANCEORHomeostasis of Blood pHORRegulation of Blood pHDr Anissa Atif Mirza
Slide 2-

Synopsis Introduction Sources of Acids and Bases in body What is Acid Base Balance? Mechanisms Regulating Blood pH. Significance of Maintaining Acid Base Balance Acid Base Imbalance and their conditions. Diagnostic Tests
Slide 3-

Introduction Acid Base Balance is a physiological and biochemical mechanism associated to body/blood pH.
Slide 4-

What Is pH? pH is a Hydrogen ion concentration. pH = - log [H+] Different compartment of human body has specific pH. pH has role in Enzyme activity.
Slide 5-

Why blood pH is Altered?
Slide 6-

Addition of various acids or alkalies by metabolic activities alters body/blood pH.
Slide 7-

Sources and Types of Acids and Alkalies Added During Metabolic Life Processes
Slide 8-

8 Acids are H+ donors. Bases are H+ acceptors, or give up OH- in solution.
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Acids and Bases can be strong or weak: A strong acid or base is one that dissociates completely in a solution - HCl, NaOH, and H2SO4 A weak acid or base is one that dissociates partially in a solution -H2CO3, C3H6O3, and CH2O, Lactate.
Slide 11-

Acidic Substances of body: Carbonic acid(H2CO3) Phosphoric acid( H3PO4) Sulphuric acid (H2SO4) Organic Acids: Lactate, Acetoactate, Pyruvate Alkaline Substances of body: Citrate Bicarbonates.
Slide 12-

What is Acid Base Balance?
Slide 13-

Homeostatic Mechanisms That Regulate Blood/Body pH
Slide 14-

Acid Base balance is a homeostatic mechanism Carried out to regulate the altered pH of blood and other body compartments to its normal constant range.
Slide 15-

Maintenance of Acid Base balance Is a prime requisite to maintain normal healthy and active life.
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Acid-Base Balance It is the regulation of HYDROGEN ions. (The more Hydrogen ions, the more acidic the solution and the LOWER the pH) The acidity or alkalinity of a solution is measured as pH
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Acid Base Balance Regulates pHWhy it is Very Essential To Regulate pH?
Slide 18-

pH of blood and other body compartments are precisely regulated. pH is always tried to be maintained to its normal constant range.
Slide 19-

Acid Base Balance maintains the blood pH at normal constant narrow range of 7.35-7.45.
Slide 20-

pH of the medium directly affects the enzyme activities Optimum pH is an essential requisite for enzyme activities and normal metabolism.
Slide 21-

It is prerequisite for regulating blood/body pH: To maintain normal/optimal Enzyme activities Normal metabolism Normal Coordination Normal Health
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22 Factors Regulating Acid Base Balance
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Acid Base Balance is Regulated By First Line of Defense Blood Buffer System Second Line of Defense Respiratory Mechanism Third Line of Defense Renal Mechanism
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24 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)
Slide 25-

Role of Blood Buffer System First line of defense in mechanism of Acid Base Balance. Acids (H+) added are neutralized by the salt part of buffer.
Slide 26-

Extracellular Buffers Bicarbonate Buffer NaHCO3/H2CO3 (20:1 at 7.4 pH) Phosphate Buffer Na2HPO4/NaH2PO4 (4:1 at 7.4 pH) Protein Buffer Na-Protein/H-Protein
Slide 27-

Intracellular Buffers Bicarbonate Buffer KHCO3/H2CO3 Phosphate Buffer K2HPO4/KH2PO4 Protein Buffer K-Hb/H-Protein
Slide 28-

Mechanism Action of Buffer Systems Buffers mixture of weak acids and its salts Resist change in pH of blood when small amount of acids or alkalis added to the medium.
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Buffers act quickly but not permanently
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30 Bicarbonate Buffer SystemRespiratory Buffer System Acid - Base balance is primarily concerned with Bicarbonate Buffer mechanism : H2CO3/ Hydrogen (H+) Bicarbonate (HCO3- ) (Alkali Reserve) H+ HCO3-
Slide 31-

Bicarbonate Buffer Bicarbonate Buffer- Chief Buffer system of Blood. NaHCO3 the salt part of buffer neutralizes the strong and non volatile acids added to blood. It constitutes Alkali reserve(HCO3-)
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33 Bicarbonate Buffer Sodium Bicarbonate (NaHCO3) and carbonic acid (H2CO3) Maintain a 20:1 ratio : HCO3- : H2CO3 HCl + NaHCO3 ↔ H2CO3 + NaCl NaOH + H2CO3 ↔ NaHCO3 + H2O
Slide 34-

Action of Bicarbonate (NaHCO3) converts strong dissociable acid into weak non dissociable acid (H2CO3) and a neutral salt without altering the pH.
Slide 35-

Weak acid H2CO3 formed during buffering action of Bicarbonate buffer is then expired out by Lungs. Thus Bicarbonate buffer is connected to the respiratory system Bicarbonate buffer is also termed as Respiratory buffer.
Slide 36-

Alkali reserve is represented by the concentration of NaHCO3 in the blood. Alkali reserve concentration(HCO3-) determines the strength of buffering action towards added H+ ions by acids. More the concentration of Alkali reserve ,more is the buffering action and vice a versa.
Slide 37-

The blood buffers are effective as long as The acid load added is not very high and The alkali reserve (HCO3 -) is not exhausted.
Slide 38-

38 Phosphate Buffer/Urine Buffer Na2HPO4/NaH2PO4 (4:1 at 7.4 pH) H+ + HPO42- ↔ H2PO4- OH- + H2PO4- ↔ H2O + H2PO42-
Slide 39-

Phosphate Buffer Mechanism When H+ ions added they are neutralized/fixed by Na2HPO4 (Alkaline Phosphate) and converted to NaH2PO4 (Acid Phosphates). These acid phosphates then excreted out through kidneys as acidic urine.
Slide 40-

Thus Phosphate Buffer is connected to Excretory system . Phosphate Buffer also termed as Urine Buffer.
Slide 41-

When an alkali enters it is buffered by the acid phosphate NaH2PO4 which converted to Na2HPO4 alkaline phosphate. Excreted in urine making it alkaline urine.
Slide 42-

42 Protein Buffers Includes hemoglobin, work in blood. Carboxyl group gives up H+ Amino Group accepts H+ The Imidazole group of Histidine present in Hb structure has buffering capacity.
Slide 43-

Role of Respiratory Mechanisms Respiratory system plays second line of defense mechanism of Acid Base Balance. Role of respiration in acid base balance is short term regulatory process.
Slide 44-

H2CO3 formed from Bicarbonate Buffer, is exhaled out through respiratory system. Increased H2CO3 stimulates the respiratory centre in Medulla Oblongata. This in turn stimulates hyperventilation which promptly removes H2CO3 from blood by expiration.
Slide 45-

Exhalation of H2CO3 is as carbon dioxide by activity of enzyme Carbonic Anhydrase of Lungs. H+ + HCO3- ↔ H2CO3 ↔ CO2 + H20
Slide 46-

Respiratory mechanism is powerful, but only works with volatile acids. Doesn’t affect fixed acids like lactic acid.
Slide 47-

Blood pH can be adjusted through respiratory mechanism By changing rate and depth of breathing.
Slide 48-

Low H2CO3 concentration in blood depresses respiratory centre ,causes hypoventilation i.e slow and shallow respiration. This retains H2CO3 in blood.
Slide 49-

If Nervous centre / Respiratory system fails. Acid Base Balance fails.
Slide 50-

50 Generation of bicarbonate by RBC LACK OF AEROBIC ACTIVITY,DIFFUSION OF CARBONDIOXIDE,H+ BUFFERED BY HHb.
Slide 51-

51 Events in lungs and tissue HCO3- HCO3- H2CO3 CO2 H2O EXPIRED AIR METABOLISM HHb HHb HbO2 HbO2 H+ H+ O2 O2 CO2 H2O H2CO3 lung tissue Isohydric transport of co2
Slide 52-

52 Role of Renal Mechanism Renal mechanism is the third line of defense mechanism. Role of renal mechanism is long term regulatory process.
Slide 53-

The acid and alkaline phosphates formed during phosphate buffering mechanism are filtered from blood and excreted out through urine. Thus the phosphate buffer system is directly connected to renal mechanism.
Slide 54-

Renal mechanism conserve and produce Bicarbonate ions ( Alkali reserve). Renal Mechanism is the most effective regulator of blood pH. If kidneys fail, pH balance fails.
Slide 55-

Renal System maintains Acid Base Balance through: Reabsorption of Bicarbonate (HCO3-) ions. Excretion of H+ ions Excretion of titrable acids(Acid Phosphates) Excretion of Ammonium ions (Glutaminase activity)
Slide 56-

56 REABSORPTION OF BICARBONATE ~Conservation of Bicarbonate ~Urine is free of HCO3- ~Simultaneous excretion of H+
Slide 57-

57 EXCRETION OF TITRABLE ACIDS ~measure of acid excreated by kidney ~no. of millilitres of N/10 NaOH required to titrate 1 litre of urine to pH 7.4 ~role of phosphate buffer
Slide 58-

58 Excretion Of H+ ions ~Elimination of nonvolatile acid ~Excretion of H+ ~Occurs in PCT ~Regeneration of bicarbonate ~H+ combine with non carbonate base and excreated
Slide 59-

59 EXCRETION OF AMMONIUM ION NH3 is obtained from Deamination of Glutamine NH4+ cant diffuse back 2/3 of body acid load liberated in the form of NH4+
Slide 60-

60 Rates of correction Buffers function almost instantaneously Respiratory mechanisms take several minutes to hours Renal mechanisms may take several hours to days
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62
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63
Slide 64-

MECHANISM FOR REGULATION OF ACID BASE BALANCE Buffer system: temporary solution Respiratory mechanism provide short time regulation Renal mechanism : permanent solution Urine pH < plasma pH ,4.5-9.5 Eliminate nonvolatile acid, buffered by cation (principally Na+) Maintain alkali reserve
Slide 65-

Acid Base ImbalanceORConditions Of Acid Base Disturbances
Slide 66-

66 The Body and pH Homeostasis of blood pH is tightly controlled by mechanisms of Acid Base Balance. Extracellular fluid = 7.4 Blood pH regulated to = 7.35 – 7.45
Slide 67-

Occurrence of Acid Base Imbalance When Factors involved in homeostatic mechanisms to regulate Acid Base Balance fails to work efficiently. Does not maintain the altered pH of blood to normal constant range. Results into Acid Base Imbalance.
Slide 68-

ACIDOSIS / ALKALOSIS Two major disturbances in Acid-Base balance Acidosis Alkalosis
Slide 69-

Conditions Of Acid Base Imbalance Acidosis /Acidemia ( Decreased pH/Increased H+ ions) Alkalosis/Alkalemia (Increased pH/Decreased H+ ions)
Slide 70-

Acidosis (Acidemia) below 7.35 Alkalosis (Alkalemia) above 7.45 Blood pH < 6.8 or > 8.0 death occurs
Slide 71-

71 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.
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72
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74
Slide 75-

Effect of Altered pH Altered pH may seriously disturbs the vital processes. Might lead to fatality.
Slide 76-

Most enzymes function only with narrow pH ranges. Extremes of pH affects the enzymatic action by protonation or deprotonation at the active sites of Enzymes. Makes Enzymes inactive.
Slide 77-

Inactivated Enzymes affect metabolic reactions and metabolic pathways. Metabolism gets deranged . Leads to metabolic syndromes.
Slide 78-

78 pH also affect excitability of Nerve and Muscle cells pH pH Excitability Excitability
Slide 79-

79 ACID-BASE REGULATION Enzymes, Hormones and ion distribution are all affected by Hydrogen ion concentrations
Slide 80-

80 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/Retention of K+
Slide 81-

CHANGES IN CELL EXCITABILITY pH decrease (more acidic) depresses the central nervous system Can lead to loss of consciousness pH increase (more basic)causes over excitability of nervous system. Tingling sensations, nervousness, muscle twitches
Slide 82-

82 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
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83 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+ Na+ Na+ Na+ Na+ Na+ Na+ H+ H+ H+ H+ H+ H+ H+ K+ K+ K+ K+ K+
Slide 84-

84 Small changes in pH can produce major disturbances Acid-base balance can also affect Electrolytes (Na+, K+, Cl-) Can also affect Hormones
Slide 85-

ACID-BASE IMBALANCE Derangements of Hydrogen/Carbonic acid (H+/H2CO3) Bicarbonate (HCO3-) concentrations In body fluids are common in conditions of Acid Base Imbalance
Slide 86-

Acid-Base Imbalances pH< 7.35 Acidosis pH > 7.45 Alkalosis
Slide 87-

87 4 Types of Primary Acid-Base Disorders
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Slide 90-

90 RESPIRATORY ACIDOSIS
Slide 91-

Respiratory Acidosis Primary Carbonic acid excess Increased H2CO3/Increased pCO2 Defect in respiratory centre of brain Defect in respiratory organ system Decreased elimination of H2CO3 by the lungs. Hypoventilation
Slide 92-

92 Increased blood levels of CO2 above 45 mm Hg. Hypercapnia – high levels of pCO2 in blood
Slide 93-

93 RESPIRATORY ACIDOSIS Respiratory acidosis develops when the lungs don't expel CO2 adequately. This can happen in diseases that severely affect the lungs.
Slide 94-

Chronic conditions: Depression of respiratory center in brain that controls breathing rate – drugs or head trauma Paralysis of respiratory or chest muscles Emphysema Asthma Pneumonia Pulmonary edema Obstruction of respiratory tract Congestive Cardiac Failure
Slide 95-

HYPOVENTILATIONCauses Respiratory Acidosis Hypo = “Under” Elimination of CO2 H+ pH
Slide 96-

96 RESPIRATORY ACIDOSIS breathing is suppressed holding CO2 in body pH = 7.1 H2CO3 HCO3- 2 20 : CO2 CO2 CO2 CO2
Slide 97-

97 RESPIRATORY ACIDOSIS 1) Obstruction of air passages Vomit, Anaphylaxis, Tracheal Cancer
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98 RESPIRATORY ACIDOSIS 2) Decreased Respiration Shallow, slow breathing Depression of the respiratory centers in the brain which control breathing rates Drug overdose
Slide 99-

99 RESPIRATORY ACIDOSIS 4) Collapse of lung Compression injury, open thoracic wound Left lung collapsed
Slide 100-

100 Respiratory Acidosis Acute conditions: Adult Respiratory Distress Syndrome Pulmonary edema Pneumothorax
Slide 101-

101 Compensation for Respiratory Acidosis Kidneys eliminate hydrogen ion and retain bicarbonate ions.
Slide 102-

102 Signs and Symptoms of Respiratory Acidosis Breathlessness Restlessness Lethargy and disorientation Tremors, convulsions, coma Respiratory rate rapid, then gradually depressed Skin warm and flushed due to vasodilation caused by excess CO2
Slide 103-

103 Treatment of Respiratory Acidosis Restore ventilation IV lactate solution Treat underlying dysfunction or disease
Slide 104-

104 RESPIRATORY ALKALOSIS
Slide 105-

105 Respiratory Alkalosis Primary Carbonic acid deficit Decreased H2CO3 pCO2 less than 35 mm Hg (hypocapnea) Most common acid-base imbalance Primary cause is hyperventilation Washes out excessive quantity of H2CO3 through expiration process of lungs.
Slide 106-

Stimulation of respiratory centre in brain Hyperventilation
Slide 107-

107 Respiratory Alkalosis Conditions that stimulate respiratory center: Oxygen deficiency at high altitudes Pulmonary disease and Congestive heart failure – caused by hypoxia Respiratory center lesions Acute anxiety Fever, anemia Early salicylate intoxication Cirrhosis Gram-negative sepsis/Meningitis
Slide 108-

108 RESPIRATORY ALKALOSIS Anxiety is an emotional disturbance The most common cause of hyperventilation, and thus respiratory alkalosis, is noted in anxiety
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109 RESPIRATORY ALKALOSIS Respiratory center lesions Damage to brain centers responsible for monitoring breathing rates Tumors Strokes
Slide 110-

110 RESPIRATORY ALKALOSIS High Altitude Low concentrations of O2 in the arterial blood reflexly stimulates ventilation in an attempt to obtain more O2 Too much CO2 is “blown off” in the process
Slide 111-

111 RESPIRATORY ALKALOSIS Fever Rapid shallow breathing blows off too much CO2
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112 RESPIRATORY ALKALOSIS Salicylate poisoning (Aspirin overdose) Ventilation is stimulated without regard to the status of O2, CO2 or H+ in the body fluids
Slide 113-

113 RESPIRATORY ALKALOSIS Kidneys compensate by: Retaining hydrogen ions Increasing bicarbonate excretion H+ HCO3- HCO3- HCO3- HCO3- HCO3- HCO3- HCO3- HCO3- HCO3- HCO3- H+ H+ H+ H+ H+ H+ H+ H+ H+ H+
Slide 114-

114 HYPERVENTILATION Causes Respiratory Alkalosis Hyper = “Over” Elimination of CO2 H+ pH
Slide 115-

115 Compensation of Respiratory Alkalosis If kidneys are functioning normal The conditions of respiratory acidosis or alkalosis are compensated. Kidneys conserve hydrogen ion Excrete bicarbonate ion
Slide 116-

116 Treatment of Respiratory Alkalosis Treat underlying cause Breathe into a paper bag IV Chloride containing solution Cl- ions replace lost bicarbonate ions
Slide 117-

117 METABOLIC ACIDOSIS
Slide 118-

118 Metabolic Acidosis Primary Alkali deficit Bicarbonate deficit - blood concentrations of bicarbonate drop below 22mEq/L Causes: Loss of bicarbonate through diarrhea or renal dysfunction. Overproduction production of acids (lactic acid or ketones) Failure of kidneys to excrete H+
Slide 119-

119 METABOLIC ACIDOSIS Occurs when there is a decrease in the normal 20:1 ratio Decrease in blood pH and bicarbonate level Excessive H+ or decreased HCO3-
Slide 120-

120 METABOLIC ACIDOSIS Any acid-base imbalance not attributable to CO2 is classified as metabolic Metabolic production of Acids Or loss of Bases
Slide 121-

121 METABOLIC ACIDOSIS The causes of metabolic acidosis can be grouped into five major categories 1) Ingesting an acid or a substance that is metabolized to acid 2) Abnormal Metabolism 3) Kidney Insufficiencies 4) Strenuous Exercise 5) Severe Diarrhea
Slide 122-

122 METABOLIC ACIDOSIS 1) Ingesting An Acid Most substances that cause acidosis when ingested are considered poisonous Examples includewood alcohol(methanol) andantifreeze(ethylene glycol) However, even an overdoseof aspirin (acetylsalicylic acid)can cause metabolic acidosis
Slide 123-

METABOLIC ACIDOSIS 2) Abnormal Metabolism The body can produce excess acid as a result of several diseases Ketoacidosis Type I Diabetes Mellitus Uncontrolled Diabetes mellitus Prolonged Starvation Lacticacidosis Shock Haemorrhage Violent Exercise-
Slide 124-

124 METABOLIC ACIDOSIS Unregulated diabetes mellitus causes ketoacidosis Body metabolizes fat rather than glucose Accumulations of metabolic acids (Keto Acids) cause an increase in plasma H+
Slide 125-

METABOLIC ACIDOSIS 3) Kidney Insufficiencies This type of kidney malfunction is called renal tubular acidosis or uremic acidosis and may occur in people with kidney failure or with abnormalities that affect the kidneys' ability to excrete acid
Slide 126-

126 METABOLIC ACIDOSIS 3) Kidney Insufficiencies Kidneys may be unable to rid the plasma of even the normal amounts of H+ generated from metabolic acids Kidneys may be also unable to conserve an adequate amount of HCO3- to buffer the normal acid load
Slide 127-

127 METABOLIC ACIDOSIS 4) Strenuous Exercise Muscles resort to anaerobic glycolysis during strenuous exercise Anaerobic respiration leads to the production of large amounts of lactic acid C6H12O6 2C3H6O3 + ATP (energy) Enzymes Lactic Acid
Slide 128-

METABOLIC ACIDOSIS 5) Severe Diarrhea Fluids rich in HCO3- are released and reabsorbed during the digestive process During diarrhea this HCO3- is lost from the body rather than reabsorbed
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METABOLIC ACIDOSIS 5) Severe Diarrhea The loss of HCO3- without a corresponding loss of H+ lowers the pH Less HCO3- is available for buffering H+ Prolonged deep (from duodenum) vomiting can result in the same situation
Slide 130-

130 Symptoms of Metabolic Acidosis Headache, lethargy Nausea, vomiting, diarrhea Coma Death
Slide 131-

131 Compensation for Metabolic Acidosis Increased ventilation. Renal excretion of hydrogen ions if possible. K+ exchanges with excess H+ in ECF. H+ into cells, K+ out of cells.
Slide 132-

132 Treatment of Metabolic Acidosis IV lactate solution
Slide 133-

133 METABOLIC ALKALOSIS
Slide 134-

134 Metabolic Alkalosis Bicarbonate Excess - concentration in blood is greater than 26 mEq/L Causes: Excess vomiting = loss of stomach acid Excessive use of alkaline drugs Certain diuretics Endocrine disorders Heavy ingestion of antacids Severe dehydration Cushings Syndrome Prolonged exposure to x rays and UV rays
Slide 135-

135 METABOLIC ALKALOSIS Elevation of pH due to an increased 20:1 ratio May be caused by: An increase of bicarbonate A decrease in hydrogen ions Imbalance again cannot be due to CO2 Increase in pH which has a non-respiratory origin 7.4
Slide 136-

136 METABOLIC ALKALOSIS Can be the result of: 1) Ingestion of Alkaline Substances 2) Vomiting ( loss of HCl )
Slide 137-

137 METABOLIC ALKALOSIS Baking soda (NaHCO3) often used as a remedy for gastric hyperacidity NaHCO3 dissociates to Na+ and HCO3-
Slide 138-

138 Compensation for Metabolic Alkalosis Alkalosis most commonly occurs with renal dysfunction, so can’t count on kidneys. Respiratory compensation difficult – hypoventilation limited by hypoxia.
Slide 139-

139 Symptoms of Metabolic Alkalosis Respiration slow and shallow Hyperactive reflexes ; tetany Often related to depletion of electrolytes Atrial tachycardia Dysrhythmias
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140 Treatment of Metabolic Alkalosis Electrolytes to replace those lost IV chloride containing solution Treat underlying disorder
Slide 141-

141 Acidosis Principal effect of acidosis is depression of the CNS through ↓ in synaptic transmission. Generalized weakness Deranged CNS function the greatest threat Severe acidosis causes Disorientation Coma Death
Slide 142-

142 Alkalosis Alkalosis causes over excitability of the central and peripheral nervous systems. Numbness Light headedness Severe Alkalosis causes : Nervousness muscle spasms or Tetany Convulsions Loss of consciousness Death
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Compensation Of Acid Base Imbalance The body response to acid-base imbalance is called compensation May be complete compensation if altered pH brought back within normal limits Partial compensation if pH range is still outside norms. Uncompensated if pH range is very out from norms.
Slide 144-

If underlying problem is respiratory, renal mechanisms can bring about metabolic compensation. If underlying problem is metabolic, hyperventilation or hypoventilation can help : respiratory compensation.
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145 ACIDOSIS deep vomiting from GI tract kidney disease (uremia) increase in plasma H+ concentration depression of nervous system
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146 ALKALOSIS overexcitability of nervous system
Slide 147-

Organ dysfunction And Acid Base Imbalance CNS – respiratory acidosis (suppression) and alkalosis (stimulation) Pulmonary – respiratory acidosis (COPD) and alkalosis (hypoxia, pulmonary embolism) Cardiac – respiratory alkalosis, respiratory acidosis, metabolic acidosis (pulmonary edema) GIT – metabolic alkalosis (vomiting) and acidosis (diarrhea) Liver – respiratory alkalosis, metabolic acidosis (liver failure) Kidney – metabolic acidosis (RTA) and alkalosis (1st Aldosterone)
Slide 148-

Organ Dysfunction Endocrine Diabetes mellitus – metabolic acidosis Addisons Disease/Adrenal insufficiency – metabolic acidosis.(Decreased H+ ions excretion) Cushing’s Syndrome – metabolic alkalosis (Increased Cortisol- Increased H+ ions excretion) Primary aldosteronism – metabolic alkalosis Drugs/toxins Toxic alcohols – metabolic acidosis ASA/Aspirin – metabolic acidosis and respiratory alkalosis( Causes Hyperventilation) Theophylline overdose – respiratory alkalosis
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149 ACID – BASE DISORDERS
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150
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Anion Gap
Slide 152-

Sum of anion and cations is always equal Sodium and Potassium accounts for 95% of cations Chloride and bicarbonate accounts for 68% of anions There is difference between measured anion and cation The unmeasured anions constitute the ANION GAP.
Slide 153-

They are protein anions ,sulphates ,phosphates and organic acid(Unmeasured Anions) AG can be calculated as (Na+ + K+)—(HCO3- + Cl-) High anion gap acidosis: renal failure, DM Normal anion gap acidosis: diarrhea Hyperchloremic acidosis
Slide 154-

Calculation Of Anion Gap Na ++ K+ = Cl- + HCO3 - + A- 136+ 4 = 100 + 25 A- = 15 mEq/L
Slide 155-

Normal AG is typically 12 ± 4 mEq/L. If AG is calculated using K+, the normal AG is 16 ± 4 mEq/L
Slide 156-

Significance of Anion Gap Calculation Calculation of Anion gap and its values help in diagnosing conditions of Acid Base Balance and Imbalance.
Slide 157-

The anion gap is increased in conditions such as metabolic acidosis: That result from elevated levels of metabolic acids (metabolic acidosis) Lactic acidosis Diabetic Ketoacidosis Renal Failure
Slide 158-

A low anion gap occurs in conditions that cause a fall in unmeasured anions (primarily albumin) OR a rise in unmeasured cations
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Calculate the Anion Gap 1. Calculate the anion gap as described. 2. An anion gap ,over 25 suggests a severe metabolic acidosis. 3. Causes of an high anion gap: ethylene glycol, lactic acid, methanol, paraldehyde, aspirin, renal failure, ketoacidosis (diabetic or ethanol).
Slide 161-

Anion Gap Acidosis: Anion gap >12 mmol/L; caused by a decrease in [HCO3 -] Balanced by an increase in an unmeasured acid ion from either endogenous production or exogenous ingestion (normochloremic acidosis).
Slide 162-

1. Normal gap 2. Increased gap Renal “HCO3” losses 2. GI “HCO3” losses Proximal RTA Distal RTA Diarrhea 1.  Acid prod 2.  Acid elimination Lactate DKA Ketosis Toxins Alcohols Salicylates Iron Renal disease Metabolic Acidosis and the Anion gap
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Henderson Hasselbalch Equation pH= pka +log [HCO3-]/[H2CO3] At pH 7.4 the ratio of HCO3-/H2CO3 is 1:20. A buffer is most effective when pH=pKa When concentration of salt and acid are equal.
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Significance of Henderson Hasselbalch Equation The equation helps in calculating pH of Buffers. The equation helps in assessing status of Acid Base balance.
Slide 166-

Stepwise Approaches History & physical examination Arterial blood gas for pH, pCO2, (HCO3) Use the HCO3 from ABG to determine compensation Serum Na, K, Cl, CO2 content Use CO2 content to calculate anion gap Calculate anion gap Anion gap = {Na - (Cl + CO2 content)} Determine appropriate compensation Determine the primary cause
Slide 167-

DIAGNOSTIC LAB VALUES & INTERPRETATION
Slide 168-

Arterial Blood Gas(ABG )Analyzer determines Acid Base Balance and Imbalance.
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169 Diagnosis of Acid-Base Imbalances Note whether the pH is low (acidosis) or high (alkalosis) Decide which value, pCO2 or HCO3- , is outside the normal range If the cause is a change in pCO2,/H2CO3 the problem is respiratory. If the change is in HCO3- the problem is metabolic.
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Normal Arterial Blood Gas (ABG)Lab Values: Arterial pH: 7.35 – 7.45 HCO3-: 22 – 26 mEq/L PCO2: 35 – 45 mmHg TCO2: 23 – 27 mmol/L PO2: 80 – 100 mmHg Base Excess: -2 to +2 Anion Gap: 12 – 14 mEq/L
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171 Example A patient is in intensive care because he suffered a severe myocardial infarction 3 days ago. The lab reports the following values from an arterial blood sample: pH 7.3 HCO3- = 20 mEq / L ( 22 - 26) pCO2 = 32 mm Hg (35 - 45)
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172 Diagnosis Metabolic acidosis With compensation
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Questions Long Essays. What is acid-base balance? Describe the homeostatic mechanism by which the blood pH is regulated. Short Notes Blood Buffer System. Role of Kidney in acid-base balance. Hb as Buffer system. Acid-Base imbalance. Metabolic Acidosis. Difference between acidosis & alkalosis. Anion Gap.
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174 ENDACID - BASE BALANCETHANKS
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