Fluid Electrolyte and acid base Imbalance BY Mihretie
Fluid, Electrolyte and acid base Imbalance BY: Mihretie G. (MSc. N) 12/23/2021 1
Learning objectives On completion of this chapter, the learner will be able to: Ø Describe the role of the vital organs in regulating the body’s fluid composition and volume. . Ø Plan effective care of patients with the following imbalances: üfluid volume deficit and fluid volume excess; üsodium deficit (hyponatremia)and sodium excess (hypernatremia); üpotassium deficit (hypokalemia) and potassium excess (hyperkalemia). 12/23/2021 2
Fundamental concepts Ø The human body functions when certain conditions are kept with in a narrow range of normal value. – Body temperature – Electrolytes – Blood PH – Blood volume Ø Body fluid contains: – water – Electrolytes – Non electrolytes (glucose, urine), and – other substances 12/23/2021 3
Body fluid compartments Ø Approximately 55 -60%of a typical adult’s weight consists of fluids. Ø These fluids are distributed in to different compartments: Ø Intracellular fluid(ICF) compartment üIs fluid with in the cells üLocated mainly (primarily) in skeletal muscle mass üContains approximately 2/3 (28 L)of the total body fluid üConstitute 45%of body weight 12/23/2021 4
Ø Extra cellular fluid(ECF) compartment üIs fluid outside cells üContains approximately 1/3(15 L) of body fluid Ø further divided in to ü Intravascular space üInterstitial space ü Trans-cellular space 12/23/2021 5
FLUILD SHIFT Ø Is the term used to classify the distribution of water. This is of three types: Ø First space fluid shift Ønormal distribution of fluid Ø Second spacing ØIs an excess accumulation of interstitial fluid Ø Third spacing ØIs losing of ECF in to spaces that do not have contribution in the equilibrium of ICF and ECF. 12/23/2021 8
• Third spacing occurs in: ü Ascites ü ü Burns Peritonitis Bowl obstruction Massive bleeding in to joint or body cavities 12/23/2021 9
S/S of third spacing ed urine out put ed heart rate ed BP Edema ed CVP ed Body weight Imbalances in fluid intake and out put 12/23/2021 10
Functions of fluid Ø Water provides about 90 -93% of the volume in the extra cellular compartment. Its functions include: – Providing form for body structures – Acts as transport vehicle – Aids in the hydrolysis of food – Acts as medium and reactant for chemical reactions – Acts as a lubricant – Cushions and acts as shock absorber 12/23/2021 11
The sources of fluid gains Ø Absorption from GIT Ø Ø Ø • ü ü Parenterally administered fluids Metabolic oxidation of foods Bathing in fresh water Routs of fluid losses Kidney (1 ml/kg/hr in all age groups Insensible loss üSkin üLungs ü Stool (GIT) 12/23/2021 12
Average in take and out put of fluids in adults • Intake Oral intake – As liquid -------1300 ml – In food --------1000 ml Metabolic oxidation ------300 ml Out put Urine-----1500 ml Stool------200 ml Insensible Lung-------300 ml Skin----600 ml • Total gain---------2600 ml Total lose-----2600 ml 12/23/2021 13
Regulation of body fluids Ø physiologic mechanisms assist in the regulation of body fluids include: i. Thirst level-primarily regulates intake Øoccurs when an increase in the extra cellular osmolality causes osmoreceptors (nerve cells in hypothalamus) to shrink. 12/23/2021 14
ii. Renal concentrating mechanisms Ø The kidney controls the concentration of most of the constitutes in body fluid, including water and electrolytes. Mediated by the function of ü Osmo receptors ü Baro receptors ü Adrenal functions-Renin- angiotensin- aldesterone system ü Release of atrial natriuretic peptide 12/23/2021 15
Organs involved in the homeostasis of body fluid include: • Kidneys • Heart and blood vessels • Lungs • Posterior pituitary gland-store and release ADH • Adrenal gland(cortex)-secretes aldostrone which increases sodium retention and potassium loss • Parathyroid gland-PTH(parathyroid hormone) regulates calcium and phosphorus balance 12/23/2021 16
Normal laboratory values used in evaluating fluid and electrolyte status in adults Serum test Cations Reference range • Sodium (Na+) ----------------135 -145 m. Eq/l • Potassium (K+)-----------------3. 5 -5. 5 m. Eq/l • Calcium (Ca 2+)-----------------8. 6 -10 m. Eq/l • Magnesium (Mg 2+)--------------1. 3 -2. 5 m. Eq/l • Anions • Chloride (Cl-)-----------------97 -107 m. Eq/l • Bicarbonate (HCO 3 -)--------------20 -30 m. Eq/l 12/23/2021 17
• • Phosphate (PO 43 -)---------------2. 8 -4. 5 m. Eq/l Osmolality------------------280 -300 m. Eq/l Blood urea nitrogen (BUN)----------5 -20 mg/dl Creatinine------------------F: 0. 5 -1. 1 mg/dl M: 0. 6 -1. 2 mg/dl BUN to creatinine ratio-----------10: 1 -15: 1 Hematocrite------------F: 35 -47% M: 42 -52% Glucose--------------------70 -105 mg/dl Albumin---------------------3. 5 -5. 0 g/dl 12/23/2021 18
Urine tests • Sodium(Na+)-------------------------75 -220 m. Eq/l • Potassium(K+)-------------------------25 -123 m. Eq/l • Chloride(Cl-)-------------------------110 -250 m. Eq/l • Specific gravity------------------------1. 016 -1. 022 • Osmolality---------------------------250900 m. Osml/kg H 2 O • PH--------------------------------Random: 4. 58. 0 Typical urine: <5 -6 12/23/2021 19
Fluid volume disterbances Fluid volume deficit (FVD) Hypovolemia Ø occurs when water and electrolytes are lost in the same proportion Ø so that the ratio of serum electrolytes to water remains the same. Ø should not be confused with dehydration Causes Inadequate fluid intake Unconsciousness/coma or inability to express thirst Oral trauma or inability to swallow Impaired thirst mechanism Withholding of fluid for therapeutic reason 12/23/2021 20
Excessive fluid losses • GI losses Vomiting Diarrhea GI suctioning Fistula drainage • Urine losses Diuretic therapy Osmotic diuresis (hyperglycemia) Salt wasting renal disease 12/23/2021 21
Ø Skin losses (salt water) üFever üExposure to hot environment üBurs and wounds that remove skin Ø Third space losses üIntestinal obstruction üEdema, ascites, burns (for the firs several days) Ø Other risk factors § Diabetic incipidus § Hemorrhage 12/23/2021 22
Clinical manifestations Ø Acute weight loss (% body weight) ü Mild FVD: 2% loss ü Moderate FVD: 2 -5%loss ü Severe FVD: 6% or more loss Ø Thirst, anorexia, nausea Ø Urine out put(oliguria) Ø Urine osmolality Ø Specific gravity 12/23/2021 23
Ø Serum osmolality ü Hematocrite ü BUN Ø Vascular volume üTachycardia, weak thready pulse üPostural hypotension üVein filling and vein refill time üHypotension and shock Ø Volume in extra cellular space üDepressed fontanel üSunken eyes and soft eyeballs 12/23/2021 24
Diagnosis Hx Physical exam ed BUN to creatnine ratio(>20: 1) ed hematocrite Electrolyte changes may occur Urine osmolality Ø ed as kidney attempt to conserve water Ø ed with DI 12/23/2021 25
Medical management • Isotonic fluid replacement Ø 0. 9%nacl solution, ringer’s lactate • After the patient becomes normotensive, a hypotonic solution Ø 0. 45%Nacl solution often used ü provide both electrolytes and water üfacilitates renal excretion of metabolic wastes • Determine the presence of renal tubular damage due to FVD 12/23/2021 26
Nursing management Ø Monitoring intake and out put at least every 8 hours Ø Monitoring daily body weight (at the same time of day) Ø Monitoring vital signs Ø Pulse-weak and rapid Ø Bp-postural hypotension Ø Temperature Ø Respiration-rapid shallow 12/23/2021 27
• Avoid orthostatic hypotension or possible syncope. Do not allow the patient to sit or standup quickly as long as circulation is compromised • Monitoring skin and tongue turgor – Mouth care every 4 hours • central venous pressure • level of consciousness • breath sounds • skin color Prevention • Identifying at risk and taking measures to minimize fluid loss 12/23/2021 28
fluid volume excess/ hypervolemia Ø Refers to an isotonic expansion of the ECF caused by the abnormal retention of water and sodium in approximately the same proportion in which they exist in the total body fluid. Causes/ contributing factors Ø Excessive sodium and water in take § Dietary intake § Ingestion of medications containing g sodium § Inadequate renal losses § Renal disease (renal failure) § Increased corticosteroid level Ø Congestive heart failure 12/23/2021 29
Clinical manifestations ü Acute weight gain (in excess of 5%) ü Pitting edema of the extremities ü Puffy eyelids ü Pulmonary edema üShortness of breathing (dyspnea) üRales, wheezing ü Cough Tachycardia-full and bounding pulse ü ed BP and CVP ü Distended neck veins ü ed Urinary out put 12/23/2021 30
Diagnosis Ø Hx Ø Ø Physical exam ed BUN Hematocrite may be ed ed Urine specific gravity (because of urine sodium level) Ø ed Serum osmolality Ø Chest X-ray reveals pulmonary congestion 12/23/2021 31
Medical management Management is directed towards the causes Ø If related to excessive administration, discontinuing the infusion Ø Diuretics (thiazides/ loop diuretics) Ø Restricting fluid and sodium intake Ø Hemodialysis/peritoneal dialysis, if pharmacologic and dietary management cannot act effectively 12/23/2021 32
Nursing management Monitoring Daily input and out put Daily body weight Degree of edema in most dependent body parts Promoting rest (bed rest favors diuresis of edema fluid) Restricting sodium intake Regular positioning (to prevent skin break down) Teaching the patient about the edema Ex. raising extremities. 12/23/2021 33
Electrolyte imbalances Ø Electrolytes in body fluids are active chemicals (cations, which carry positive charges, and anions, which carry negative charges). 12/23/2021 35
• The major cations in • The major anions are: body fluid are: – chloride, – sodium, – bicarbonate, – potassium, – phosphate, – sulfate, and – calcium, – proteinate ions. – magnesium, and – hydrogen ions. 12/23/2021 36
Ø Functions of electrolytes include. ü regulating water balance ( Na+) ü acid-base regulation (e. g. HCo-3 Na+, Cl) ü enzyme reaction (e. g. Mg 2+) ü neuromuscular function( e. g. k+, Ca 2+, Na+) Ø risk factors: üOlder clients üCRD, or endocrine disorder üMentally impaired clients ü medications that alter fluid and electrolyte status. 12/23/2021 37
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Alteration in Sodium Balance Ø Functions of SODIUM üThe osmolality of the ECF üNormal neuromuscular function üAcid base balance üNumerous vital chemical reactions. 12/23/2021 39
Sodium deficit /Hyponatremia/ Ø serum sodium level below normal (< 135 m. Eq/L [135 mmol/L]). Ø Can occur with FVD or FVE /hypo-osmotic dehydration or hypoosmotic rehydration/. Contributing factors üvomiting, diarrhea, fistulas, or sweating ü overuse of diuretics, particularly in combination with a lowsalt diet. üAdrenal insufficiency üExcess ADH, SIADH 12/23/2021 40
Clinical features Ø Skin- Poor skin turgor, dry mucosa, decreased saliva Ø CVS- orthostatichypotension, ↑ pulse. Ø Neurologic changes Øsigns of ICP, such as lethargy, confusion, muscle twitching, focal weakness, hemiparesis, papilledema, and seizures, Ø GI-anorexia, nausea, and abdominal cramping Ø MSK- muscle cramps, and a feeling of exhaustion Ø Lab. findings Ø ↓ serum and urine sodium, ↓ urine specific gravity 12/23/2021 41
Medical management Ø Sodium replacements üIncrease oral intake üLactated Ringer’s solution or isotonic saline (0. 9% Na. Cl) üHyponatremia associated with FVD üIV saline infusion üIf sever hyponatremia infusion of hypertonic solution (2% - 3% saline) » Hyponatremia associated with FVE • Osmotic diuresis 12/23/2021 42
Ø If hyponatremia associated with SIADH § agents that antagonize ADH such as lithium & demeclocycline (declomycin) ü Duretics, Dietary therapy, Water restriction Nursing management § Early detection of clinical features § Monitoring intake and output, and daily body weight, § Encourage foods & fluids with a high sodium content § Restriction of fluid intake if the primary problem is water retentions 12/23/2021 43
Sodium excess /hypernatremia/ Ø is a higher-than-normal serum sodium level (exceeding 145 m. Eq/L [145 mmol/L]. Ø It can be caused by a gain of sodium in excess of water or by a loss of water in excess of sodium. Ø can occur with normal fluid volume or with FVD or FVE /hyperosmotic dehydration or hyper-osmotic rehydration/. 12/23/2021 44
Causes/ contributing factors Ø Fluid deprivation Ø Administration of hypertonic enteral feedings without adequate water supplements Ø watery diarrhea Ø Diabetic incipidus Ø Cushing's disease Ø greatly increased insensible water loss Ø Increased sweating Ø heat stroke Ø near-drowning in sea water Ø IV administration of hypertonic saline or excessive use of sodium bicarbonate also causes 12/23/2021 45
Clinical features ØThirst, Dehydration Ødry, swollen tongue and sticky mucous membranes ØNeurologic symptoms • moderate hypernatremia Ø restlessness and weakness • severe hypernatremia Ødisorientation, delusions, and hallucinations. ØPermanent brain damage Lab. Findings: • ↑ serum sodium, ↓ urine sodium, • ↑ urine specific gravity and osmolality 12/23/2021 46
Medical Managment Ø Gradually lowering of the serum sodium level Ø Drug therapy üHypotonic IV infusion of Na. Cl solution (if caused by fluid loss) üDiuretics (such as furosemide /lasix, if caused by inadequate renal excretion of sodium üNon saline isotonic solution (e. g. D 5 W) to replace water without sodium. üTreatment of underlined disease process 12/23/2021 47
Nursing management Ø Promotion of sodium balance & prevention of complications resulting from hypernatremia Ø Monitor for indication of dehydration Ø Monitor V/S, body wt & trends, intake & out put Ø Maintain patient IV access Ø Monitor patient’s response to parentral fluid administration Ø Maintain sodium restriction 12/23/2021 48
Alteration in potassium balance Ø Potassium is the major intracellular electrolyte. Ø Potassium is important in neuromuscular function. Ø Influences both skeletal and cardiac muscle activity. ØFor example, alterations in its concentration change myocardial irritability and rhythm. Ø The normal serum potassium concentration ranges from 3. 5 to 5. 5 m. Eq/L (3. 5– 5. 5 mmol/L) 12/23/2021 49
Ø The kidneys are the primary regulators of potassium balance /80% of the potassium is excreted via urine/. Ø Renal excretion of potassium can be affected by: ØSerum potasium level ØAldosterone Ø Because the kidneys do not conserve potassium as well as they conserve sodium, potassium may still be lost in urine in the presence of a potassium deficit. Ø 20% of potassium is lost through the bowel and in sweat. 12/23/2021 50
Potasium deficit /Hypokalemia/ • Occur when the serum potassium level is below 3. 5 m. Eq/L (3. 5 mmol/L) Contributing factors üDiarrhea, vomiting, gastric suction ü corticosteroid administration ü hyperaldosteronism übulimia üdiuretics ü alkalosis üstarvation 12/23/2021 51
Clinical features Ø Ø Ø GI-Fatigue, anorexia, nausea and vomiting, abdominal distention, decreased bowel motility. GUT- polyuria, dilute urine CVS- ventricular asystole or fibrillation, ↓ BP MSK-muscle weakness, hypoactive reflexes, paresthesias, leg camps Ø ECG: ü flattened T waves, ü prominent U waves, ü ST depression, ü prolonged PR interval. 12/23/2021 52
Medical management Ø ed daily dietary intake Ø Potassium sparing diuretics. e. g. spironulactone Ø (eg, aldactone), triamterne (dyrenium) & Ø amilorid (midamor) Ø Potassium supplements (KCl, potassium glauconate, Ø 12/23/2021 potassium citrate or combination of these) 53
Nursing Alert! Ø Potassium infusion rate should not exceed 20 m. Eq/hr under any circumstances Ø Potassium never administered as an IM or SC injection and IV push Ø Because KCl can cause nausea and vomiting it should not be taken in an empty stomach Ø Avoid potassium-excreting diuretics like loop diuretics and thiazides 12/23/2021 54
Potasium excess/Hyperkalamia/ Ø Occur when the serum potassium level exceeds 5. 5 mmol/L Ø seldom occurs in patients with normal renal function. Ø is often due to iatrogenic reasos Ø less common, but more dangerous than hypokalemia /cardiac arrest is more frequently associated with high serum potassium levels/. 12/23/2021 55
Causes Ø decreased renal excretion Ø hypoaldosteronism and Addison’s disease Ø Medications such as potassium chloride, heparin, ACE inhibitors, captopril, NSAIDs, and potassium-sparing diuretics. Ø a high intake of potassium in patients with impaired renal function Ø improper use of potassium supplements Ø metabolic acidosis Ø crush injury Ø burns Ø stored bank blood transfusions Ø rapid IV administration of potassium 12/23/2021 56
Clinical features Ø Vague muscular weakness, tachycardia → bradycardia Ø dysrhythmias, flaccid paralysis, paresthesias, intestinal colic, cramps, irritability, anxiety. Ø Lab- sed serum potassium level Ø ECG: ü tall tented T waves ü prolonged PR interval and QRS duration, ü absent P waves ü ST depression. 12/23/2021 57
Hypokalemia hyperkalemia • ECG: Ø Flattened T waves, Ø Prominent U waves, Ø ST depression, Ø prolonged PR interval. Ø Tall tented T waves Ø Prolonged PR interval and QRS duration, Ø Absent P waves Ø ST depression. 12/23/2021 58
Medical management Ø Restriction of dietary potassium & potassium containing medications Ø Emergency pharmacologic therapy Ø When serum K+ level are dangerously elevated, it may be necessary to administer IV calcium gluconate. Ø Na. HC 03–to alkalinize plasma & cause a temporary shift of K+ in to the cells Ø Na+ also antagonizes the effect of K+ on heart Ø Insulin & hypertonic dextrose solution also cause a temporary shift of K+ in to the cells. Ø Monitor ECG 12/23/2021 59
Nursing Management Ø Patients at risk for potassium should be identified so they can be monitored closely for signs of hyperkalemia such as: Ømuscle weakness Ødysrhythmias. ØParesthesias Ø GI symptoms such as nausea and intestinal colic Ø For patients at risk, serum potassium levels are measured periodically. 12/23/2021 60
Alteration in calcium balance Significance of calcium Ø More than 99% of the body’s calcium is located in the skeletal system Ø is a major component of bones and teeth. Ø The normal total serum calcium level is 8. 5 to 10. 5 mg/d. L(2. 1– 2. 6 mmol/L). Ø It exists in plasma in three forms: ü ionized üBound üComplexed 12/23/2021 61
Ø absorbed from foods in the presence of normal gastric Ø acidity and vitamin D. Ø excreted primarily in the feces, the remainder in urine. Ø The serum calcium level is controlled by PTH and calcitonin. Ø plays a major role in: ü transmission nerve impulses and helps to regulate muscle contraction and relaxation. üactivating enzymes üblood coagulation. 12/23/2021 62
Calcium deficit (hypocalcemia) Ø Serum calcium <8. 5 mg/d. L Causes Ø Hypoparathyroidism Ø Malabsorption Ø pancreatitis Ø Alkalosis Ø vitamin D deficiency generalized peritonitis – massive transfusion of citrated blood – chronic diarrhea – decreased parathyroid hormone, and – diuretic phase of renal failure 12/23/2021 63
Clinical features ü Numbness, tingling of fingers, and toes ü positive Trousseau’s sign ü Chvostek’s sign ü seizures ü hyperactive deep tendon reflexes ü carpopedal spasms ü irritability & anxiety ü Bronchospasm ü impaired clotting time ü ↓ prothrombin ü ECG: ü prolonged QT interval and lengthened ST. 12/23/2021 64
Medical and Nursing managements Ø Acute symptomatic hypocalcaemia is life-threatening and requires üIV administration of calcium gluconate, calcium chloride, üDilute in D 5 W and given as a slow IV bolus or a slow IV infusion using a volumetric infusion pump. üObserver the IV site for any evidence of infiltration üDo not use a 0. 9% sodium chloride /it increase renal calcium loss/. 12/23/2021 65
Ø Avoid Solutions containing phosphates or bicarbonate because they will cause precipitation when calciumis added. ü Vitamin D therapy ü Antacids such as- Aluminum hydroxide, calcium acetate, or calcium carbonate ü Increasing the dietary intake of calcium to at least 1, 000 to 1, 500 mg/dy 12/23/2021 66
Calcium excess (hypercalcemia) Ø Serum calcium >10. 5 mg/d. L Causes ü Hyperparathyroidism ü prolonged immobilization ü overuse of calcium supplements ü Thiazide diuretics ü vitamin D excess ü oliguric phase of renal failure ü corticosteroid therapy ü digoxin toxicity 12/23/2021 67
Clinical features Ø GI- constipation, anorexia, nausea and Vomiting Ø GUT- polyuria and polydipsia, flank pain, calcium stones Ø CVS- Arrithymia & Bradicardia Ø MSK- Muscular weakness, deep bone pain, pathologic fractures Ø CNS- lethargy(a state of physical slowness and mental dullness resulting from tiredness, disease, or drugs ) 12/23/2021 68
Medical management Ø Administering fluids to dilute serum calcium Ø 0. 9% sodium chloride solution Ø IV phosphate Ø promotecalsium excretion by the kidneys Ø Furosemide (Lasix) Ø mobilizing the patient Ø restricting dietary calcium intake Ø Administering Calcitonin Ø Treatment of underlined diseases 12/23/2021 69
Nursing management Ø monitor for hypercalcemia in patients at risk Ø Promote patient mobility Ø encourage fluid intakes Ø Encourage adequate fiber in the diet Ø Safety precautions if mental symptoms of hypercalcemia are present Ø Assesse patient for signs and symptoms of digitalis toxicity. 12/23/2021 70
Alteration in magnesium balance Ø Significance of magnesium Ø most abundant intracellular cation. /Next to potassium/ Ø is activator for many intracellular enzyme systems Ø Important in neuromuscular function Øan excess of magnesium diminishes the excitability of the muscle cells, whereas a deficit increases neuromuscular irritability and contractility. Ø have a direct vasodilator effect on peripheral arteries and arterioles. 12/23/2021 71
Magnesium deficit (hypomagnesaemia) Ø Serum magnesium <1. 5 mg/d. L Causes üGI suction & diarrhea üHyperparathyroidism ü hyperaldosteronism üdiuretic phase of renal failure üdiabetic ketoacidosis ümalabsorptive disorders ü refeeding after starvation üchronic laxative use ü rapid administration of citrated blood 12/23/2021 72
Clinical features – Neuromuscular irritability – Positive Trousseau’s and Chvostek’s signs – insomnia and mood changes – Vomiting &anorexia – increased tendon reflexes 12/23/2021 73
Medical and Nursing managements Ø Encouraging magnesium rich diet Ø IV administration of magnesium sulfate by an infusion at a rate not to exceed 150 mg/min. Ø Determine the risk for hypomagnesaemia and observe for its signs and symptoms Ø Assess the presence of dysphagia before oral administration of food and medication 12/23/2021 74
Magnesium excess (hypermagnesemia) Ø Serum magnesium >2. 7 mg/d. L Causes/ contributing factors üOliguric phase of renal failure üadrenal insufficiency ü excessive IV magnesium administration üDKA üExcessive use of antacids 12/23/2021 75
Clinical features ØFlushing & diaphoresis Ø hypotension Ø drowsiness Ø hypoactive reflexes Ø depressed respirations Ø cardiac arrest and coma 12/23/2021 76
Acid base balance and imbalances Objectives… Ø Explain the role of the lungs, kidneys, and chemical buffers inmaintaining acid–base balance. Ø Compare metabolic acidosis and alkalosis with regard to causes, clinical manifestations, diagnosis, and management. Ø Compare respiratory acidosis and alkalosis with regard to causes, clinical manifestations, diagnosis, and management. Ø Interpret arterial blood gas measurements. Ø 12/23/2021 77
Ø What is PH? Ø The normal PH value is: – 7. 4 for arterial blood – 7. 35 for venous blood and intestinal fluid, and – 7. 0 for intercellular fluid. • Acid-base balance is situation in which the PH of the blood is maintained between 7. 35 and 7. 45. • Imbalances occur in the form of: – Alkalosis- arterial blood PH rises above 7. 45 – Acidosis- A drop in arterial Ph to below 7. 35 12/23/2021 78
Acid Base Regulatory Mechanisms • Chemical Acid-Base Control /buffer system § Bicarbonate § phosphate § Proteins • Respiratory Acid Base Control § Carbon dioxide • Renal Acid Base Control – Bicarbonate, acids, ammonium 12/23/2021 79
Chemical Mechanisms (Buffers Ø Buffers are the first line of defense against changes in H+ concentration. Ø By acting as ‘H+ sponges’; buffers can bind H+ when the concentration is too high or release H+ when concentration is too low. Ø Fluid buffers are composed of chemicals (e. g. bicarbonate, phosphate) & proteins (e. g. albumin, globulins, hemoglobin). 12/23/2021 81
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Phosphate Buffer System Ø This system is an effective buffer in urine and intracellular fluid (ICF) Ø Works much like the bicarbonate system Ø System involves: Ø Sodium Monohydrogen phosphate (Na 2 HPO 42 -) Ø H+ + HPO 42 - H 2 PO 4 - 12/23/2021 83
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