Download - Keseimbangan Asam-Basa dan Elektrolit.ppt
ELECTROLYTES & ELECTROLYTES & ACID-BASE HOMEOSTASISACID-BASE HOMEOSTASIS
(Keseimbangan Asam-Basa dan Elektrolit)(Keseimbangan Asam-Basa dan Elektrolit)
FAKULTAS KEDOKTERAN GIGIUNIVERSITAS ANDALAS
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Electrolyte BalanceElectrolyte Balance• Electrolytes are salts, acids, and bases,
but electrolyte balance usually refers only to salt balance
• Salts are important for:– Neuromuscular excitability– Secretory activity– Membrane permeability– Controlling fluid movements
• Salts enter the body by ingestion and are lost via perspiration, feces, and urine
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Electrolytes – The Ion Components Inside and Electrolytes – The Ion Components Inside and Outside the Cells Are Not the Same.Outside the Cells Are Not the Same.
Electrolyte Symbol Reference range(serum)
Potassium K+ 3.7-5.2 mEq/L
Magnesium Mg2+ 1.8-2.4 mg/dL
Phosphate PO4- 4.5-6.0 mg/dL ( 11 yrs)3.0-4.5 mg/dL ( 12 yrs)
Sodium Na+ 136-145 mEq/L
Chloride Cl- 98-108 mEq/LBicarbonate HCO3- 22-32 mEq/LCalcium Ca2+ 8.9-10.2 mg/L
ICF
ECF
Adapted from Sara Duesterhoeft’s lecture, 2002.
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Sodium in Fluid and Electrolyte Sodium in Fluid and Electrolyte BalanceBalance
• Sodium holds a central position in fluid and electrolyte balance
• Sodium salts:– Account for 90-95% of all solutes in the ECF– Contribute 280 mOsm of the total 300 mOsm
ECF solute concentration• Sodium is the single most abundant cation in
the ECF
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SodiumSodium• Plays major role in maintaining ECF
concentration (osmolality) and volume
• Sodium is the only cation exerting significant osmotic pressure
• Important in generation and transmission of nerve impulses
• Important in acid-base balance
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HypernatremiaHypernatremia• Hypernatremia due to
– Water loss or– Sodium gain
• Hypernatremia results in– Hyperosmolality → water shifts out of cells →
cellular dehydration
• Primary protection against hypernatremia is thirst
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HypernatremiaHypernatremia
• Manifestations include thirst, lethargy, seizures, and coma
• Hypernatremia secondary to water deficiency often due to inability to get fluids
• Also due to deficiency in ADH
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HyponatremiaHyponatremia• Due to:
– loss of Na-containing fluids, or – water excess (dilutional hyponatremia)
• Hyponatremia → hypoosmolality → water moves into cells
• Clinical manifestations include confusion, nausea, vomiting, seizures, and coma
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PotassiumPotassium• Potassium major ICF cation
• Potassium is necessary for– Transmission and conduction of nerve
impulses – Normal cardiac rhythms– Skeletal muscle contraction– Acid-base balance
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PotassiumPotassium
• Critical to action membrane potential
– Sources of potassium • Fruits and vegetables (bananas and
oranges)• Salt substitutes • Potassium medications (PO, IV)• Stored blood
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HyperkalemiaHyperkalemia
• Causes– Increased retention
• Renal failure• Potassium sparing diuretics
– Increased intake– Mobilization from ICF
• Tissue destruction • Acidosis
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HyperkalemiaHyperkalemia
• Clinical Manifestations :– Skeletal muscles weak or paralyzed
– Ventricular fibrillation or cardiac standstill
– Abdominal cramping or diarrhea
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HypokalemiaHypokalemia
• Causes– Increased loss
• Certain diuretics • GI losses• Movement into cells
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HypokalemiaHypokalemiaClinical ManifestationsClinical Manifestations
• Potentially lethal ventricular arrhythmias • Increased digoxin toxicity in those taking
the drug• ECG changes• Skeletal muscle weakness and paralysis • Muscle cell breakdown
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HypokalemiaHypokalemiaClinical ManifestationsClinical Manifestations
• Decreased GI motility
• Altered airway responsiveness
• Impaired regulation of arterial blood flow
• Diuresis
• Hyperglycemia
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Kalsium & FosforKalsium & Fosfor
• Keduanya membentuk garam appatite didalam tulang & gigi (80-90%).
• Absorpsi paling baik jika perbandingan dalam lumen usus Ca : P = 1 : 1 s/d 1 : 3
• Bila perbandingan > 3, maka absorpsi Ca terhambat (Rachitis).
• Makanan penyebabnya disebut rachitogenik
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Interaksi yang MenghambatInteraksi yang Menghambat
• Beras mengandung asam fitat (P) sehingga mengikat Ca membentuk Ca-fitat.
• Sayuran & buah yang mengandung asam oksalat juga akan menghambat absorpsi Ca.
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Fungsi CaFungsi Ca
• Penggumpalan darah• Kontraksi otot• Penghantar stimulus saraf• Aktifitas enzim tertentu• Membentuk hidroksiapatit pada tulang
dan gigi
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Fungsi PFungsi P
• Ikatan fosfat berenergi tinggi ATP, ADP, kreatin-P, PEP, dll.
• Komponen membran sel fosfolipid• Membentuk hidroksiapatit pada tulang dan
gigi
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Defisiensi CaDefisiensi Ca
• Rickets pada anak-anak• Osteomalacia (osteoporosis) pada dewasa• Tetani / kejang • Postmenopause (estrogen rendah)
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Defisiensi PDefisiensi P
• Gangguan absorpsi di usus• Ekskresi berlebihan melalui ginjal• Sindrom Milkman• Sindrom de Toni Fanconi
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Klor (Cl)Klor (Cl)
• Komponen garam NaCl.• Asam-basa (Chloride shift).• Pengaturan osmotik.• Komponen HCl lambung.• Ekskresi melalui keringat.• Defisiensi Cl menyebabkan alkalosis
metabolik akibat muntah proyektil.
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MagnesiumMagnesium
• Terdapat dalam semua jaringan tubuh.• Komponen ATP.• Berperan dalam sintesis protein.• Berperan dalam kontraksi otot.• Absorpsi usus meningkat bila terdapat Ca,
P, & protein.• Ekskresi melalui ginjal.
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Defisiensi MagnesiumDefisiensi Magnesium
• Terjadi pada alkoholisme/malnutrisi.• Mempengaruhi sistem:
1. kardiovaskuler2. ginjal
3. neuromuskuler
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Fluor (F)Fluor (F)
• Komponen jaringan keras, tu gigi.• Melindungi email gigi.• Fluor bersifat racun thd enolase (glikolisis)• Air PAM mengandung fluor 1 -2 ppm.• Defisiensi fluor --> karies dentis.• Kelebihan fluor --> fluorosis (mottled enamel)
= cekungan-cekungan kuning kecoklatan pada email & dentin
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• Acidosis: plasma pH– Protein damage– CNS depression
• Alkalosis: plasma pH– Hyperexcitability– CNS & heart
• Buffers: HCO3- & proteins
• H+ input: diet & metabolic• H+ output: lungs & kidney
Acid/Base Homeostasis: OverviewAcid/Base Homeostasis: Overview
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Acid/Base Homeostasis: OverviewAcid/Base Homeostasis: Overview
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• Buffers–Blood seconds–Intracellular minutes
• Lung hours
• Kidneys days
Removing Acid or Base
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• pH = pKa + log [HCO3-]/[H2CO3]
• pH = pKa + log [HCO3-]/0.03 x PCO2
• 7.4 = 6.1 + log 20 / 1
• 7.4 = 6.1 + 1.3
• Plasma pH equals 7.4 when buffer ratio is 20/1• The solubility constant of CO2 is 0.03
Henderson-Hasselbalch equationHenderson-Hasselbalch equation
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Physiological Buffer SystemsPhysiological Buffer Systems
• The respiratory system regulation of acid-base balance is a physiological buffering system
• There is a reversible equilibrium between:– Dissolved carbon dioxide and water– Carbonic acid and the hydrogen and
bicarbonate ionsCO2 + H2O H2CO3 H+ + HCO3¯
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Physiological Buffer SystemsPhysiological Buffer Systems
• During carbon dioxide unloading, hydrogen ions are incorporated into water
• When hypercapnia or rising plasma H+ occurs:– Deeper and more rapid breathing expels more
carbon dioxide– Hydrogen ion concentration is reduced
• Alkalosis causes slower, more shallow breathing, causing H+ to increase
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Acid-base disturbancesAcid-base disturbances
• Plasma pH may be affected by a change in either the [bicarbonate] or the PCO2:– When the primary change is in the PCO2, the
disturbance is called respiratory; – When it is the [bicarbonate], it is called
metabolic:
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Acid-base changes in Acid-base changes in acidosis and alkalosisacidosis and alkalosis
Acid-base Disturbance pH HCO3- PCO2
Respiratory acidosis Respiratory alkalosis Metabolic acidosis
Metabolic alkalosis
Thicker arrows indicate primary disorder
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• Metabolic Acidosis: Diabetic ketoacidosis, diarrhea
• Metabolic Alkalosis: antacid, vomiting (will loose Cl too)
• Respiratory Acidosis: Hypoventilation, pulmonary edema, narcotic, chronic bronchitis
• Respiratory Alkalosis: Hyperventilation, asthma, pneumoni, brain injury, anxiety
Clinical Causes …
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CompensationCompensation
• The purpose of the compensation is to return the blood pH to normal
• The change in the PCO2 in the metabolic disorders represents the lung’s role in compensation
• The change in the bicarbonate level represents the kidney’s attempt to compensate for the respiratory acidosis or alkalosis
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Metabolic and Respiratory Acid-Base Changes in Blood
pH pCO2 HCO3-
Acidosis1. Acute metabolic N 2. Compensated metabolic N 3. Acute respiratory N4. Compensated respiratory N
Alkalosis1. Acute metabolic N 2. Chronic metabolic 3. Acute respiratory N4. Compensated respiratory N =decreased; =increased; N=normal
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Normal values for arterial blood gases
Blood Gas Parameter Parameter Reported and Symbol Used
Normal Value
Carbon dioxide tension*
PCO2 35 – 45 mm Hg (average, 40)
Oxygen tension* PO2 80 – 100 mm Hg
Oxygen percent saturation
SO2 97
Hydrogen ion concentration*
pH 7.35 – 7.45
Bicarbonate HCO3- 22 – 26 mmol/L
Arterial Blood Gases (ABG)
* Indicates measured parameter Normal values may differ slightly in exams
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KepustakaanKepustakaan
• Booth, HD. Integrative Physiology II: Fluid and electrolyte balance.PPt. 2004
• Hale, J. Fluid and electrolytes. PPT. 2009.• Hardjasasmita, P. Ikhtisar: biokimia dasar B. Balai Penerbit
FKUI. Jakarta: 50 - 6. 1993.• Ivkovic, A ., Dave, R. Renal review. PPT. 2007• Mineral 2007. website.• Rashid, FA. Respiratory mechanism in acid-base homeostasis. PPT. 2005.