TOPIC 2: ELECTROLYTES (CC LAB)

Sodium (Na⁺)

Major extracellular cation

Potassium (K⁺)

Major intracellular cation

Chloride (Cl⁻)

Major extracellular anion

Phosphate, proteins

Major intracellular anions

Calcium (Ca²⁺)

Most abundant cation in the body

Henderson–Hasselbalch equation

Principle that blood pH is based on

Carbonic anhydrase

Enzyme converting CO₂ + H₂O → H₂CO₃

Bicarbonate–carbonic acid buffer

Main blood buffer

Kidneys

Organ regulating bicarbonate

Lungs

Organ regulating CO₂

Chloride shift

Exchange of Cl⁻ & HCO₃⁻ in RBCs

Sodium

Electrolyte determining plasma osmolality

Calcium

Vitamin D–dependent electrolyte

Aldosterone

Hormone increasing Na⁺ reabsorption

Calcitonin

Hormone lowering serum calcium

PTH

Hormone increasing serum calcium

Ion-selective electrodes

Electrolyte measurement method

Serum or heparinized plasma

Best specimen for electrolytes

Hyperventilation

Compensation for metabolic acidosis

Hypoventilation

Compensation for metabolic alkalosis

Bicarbonate

Major component of total CO₂

Hypernatremia

High sodium

Hyponatremia

Low sodium

Hyperkalemia

High potassium

Hypokalemia

Low potassium

Hyperchloremia

High chloride

Hypochloremia

Low chloride

1. Metabolic acidosis

Low bicarbonate

Metabolic alkalosis

High bicarbonate

Carbonic acid

Acid in bicarbonate buffer

CO₂

Respiratory acid

Sodium

Ion exchanged with H⁺ in renal tubules

Potassium

Electrolyte most affected by hemolysis

Phosphate buffer

Major intracellular buffer

135–145 mmol/L

Reference value of normal Na+ (sodium)

3.5–5.2 mmol/L

Ref value of normal K+ (potassium)

98–107 mmol/L

Normal ref range of CI

22–29 mmol/L

Normal Ref Value of HCO₃

Hemolysis

Main cause of pseudohyperkalemia

Chloride

Electrolyte following sodium

Chloride

Electrolyte inversely related to bicarbonate

Respiratory acidosis

Excess CO₂ retention

Respiratory alkalosis

Low CO₂ (hyperventilation)

Bicarbonate test

Test measuring total CO₂

Potassium

Strongest intracellular cation

Potentiometry

pH electrode principle

Albumin

Major unmeasured anion

Na⁺ – (Cl⁻ + HCO₃⁻)

Anion gap formula

8–16 mmol/L

Normal anion gap

Stability of internal environment

Homeostasis

Stability of internal environment

Chloride

Major anion of gastric secretions

Sodium

Main cation of sweat

Potassium

Major cation of saliva

Hydrogen (H⁺)

Ion lost during vomiting

Bicarbonate (HCO₃⁻)

Ion lost during diarrhea

ADH (Vasopressin)

Hormone that retains water via kidneys

Diabetes insipidus

Condition caused by ADH deficiency

SIADH

Condition caused by excess ADH

ADH

Major regulator of plasma osmolality

Osmometer

Instrument measuring osmolality

Hypoalbuminemia

Decreased anion gap often due to

Ketoacidosis

Increased anion gap acidosis cause

pH increases

Effect of hyperventilation on pH

pH decreases

Effect of hypoventilation on pH

Metabolic acidosis

Acid-base disorder due to diarrhea

Metabolic alkalosis

Acid-base disorder due to vomiting

Calcium

Electrolyte needed for muscle contraction

Magnesium

Electrolyte paired with magnesium in ATP reactions

Respiratory system

First response to acute acid–base disturbances

Kidneys

Chronic compensator for acid–base balance

Hyponatremia + hyperkalemia

Aldosterone deficiency leads to

Hypernatremia + hypokalemia

Aldosterone excess leads to

Sodium

Electrolyte controlling nerve impulses

Potassium

Electrolyte essential for cardiac rhythm

Hemoglobin

Primary buffer in RBCs

Bicarbonate

Form of CO₂ transported in blood (major)

H⁺ excretion

Acid-base mechanism lost in kidney failure

Chloride

Ion retained in compensation for metabolic acidosis

Bicarbonate

Ion excreted in metabolic alkalosis

Falsely increases

Effect of hemolysis on K⁺

Increases potassium

Effect of prolonged tourniquet use on electrolytes

Hydrogen (H⁺)

Ion that determines acid concentration

Chloride shift

Transport form of chloride in cells

Phosphate buffer

Buffer active in urine

Increase ventilation

Lung response to acid accumulation

Decrease H⁺ excretion

Kidney response to alkalosis

Magnesium

Major intracellular cation after potassium

Sodium

Ion increased in dehydration

Osmolal gap

Difference between measured and expected osmolality

Phosphate

Electrolyte mostly found in bone with calcium

Magnesium

Ion necessary for Na⁺/K⁺ pump activity

Bicarbonate

Substance combining with H⁺ in buffering

Kidneys

Organ responsible for generating new bicarbonate

Ketoacidosis

Term for excessive acid production from fat metabolism

• intravasvular

• intertitial fluid

• Transcellular fluid

3 types of Extracellular

Plasma

Example of intravascular fluid

Electroneutrolity

Balance of charge or equal amount

Potassium, Magnesium, Phosphorus

Intracellular fluid

Sodium, Chloride, Bicarbonate

Extracellular