Electrolytes and Body Fluids

Flashcards covering key concepts about electrolytes, their functions, and imbalances.

Electrolytes

Substances that contain free ions and conduct electricity.

Cations

Positively charged ions.

Anions

Negatively charged ions.

Importance of Electrolytes

Maintain water distribution, regulate pH, and are required for proper heart and muscle function.

Body Fluid Compartments

Intracellular (ICF) and Extracellular (ECF).

Most important extracellular cation

Sodium (Na+)

The main excretory route of sodium

kidney

Hyponatremia

Condition where serum sodium level is under 135mmol/L.

Common symptoms of Hyponatremia

Headaches, nausea, lethargy, confusion, and muscle weakness.

Potassium (K+)

Most important intracellular cation.

Normal range of Potassium

3.5 - 5.0 mmol/L

Main excretory route of Potassium

Kidney

Hyperkalaemia

Cardiac arrest and requires urgent treatment

Hypokalaemia

Cardiac arrhythmias and may require urgent treatment if severe.

Causes of Hypokalaemia

Decreased intake, transcellular potassium movement, renal loss, extrarenal loss.

Causes of Hyperkalemia

Excessive intake, transcellular potassium movement (trauma, vigorous exercise), decreased renal excretion.

Potassium

Major cation of the ICF and a cofactor for some enzymes.

Effect of a potassium excess (hyperkalemia)

Nerve and muscle dysfunction, including cardiac arrest.

Effect of a potassium deficiency (hypokalemia)

Inhibits nerve and muscle function.

Calcium Functions

Necessary for muscle contraction, neurotransmission, blood clotting, hormone actions, and bone and tooth development.

Hormones that regulate calcium homeostasis

Parathyroid hormone, calcitonin, and calcitriol.

Effects of Hypercalcemia

Reduces sodium permeability, inhibits depolarization of nerve and muscle cells, causes muscular weakness, depressed reflexes, and cardiac arrhythmia.

Effects of Hypocalcemia

Increases sodium permeability, causing nervous and muscular systems to be overly excitable, and can cause muscle tetanus.

Chloride (Cl-)

Major anion in the extracellular space.

Anion Gap Formula

{[Na+] + [K+]} - {[Cl-] + [HCO3 -]}

Causes of Hypochloremia

Cl- loss similar to sodium loss, vomiting, pyloric stenosis, and excessive sweating and urination.

Causes of Hyperchloremia

Kidney failure, dehydration, metabolic acidosis, and chloride retention.

Magnesium (Mg2+)

Important intracellular cation that's a co-factor for enzymes involved in energy metabolism.

Causes of Hypomagnesaemia

Decreased intake, increased cell uptake, renal loss, excessive use of diuretics, and cardiac arrhythmia’s

Causes of Hypermagnesaemia

Increased intake, cell release, decreased excretion, and renal failure.

Lithium

Therapeutic agent prescribed to patients with acute mania or chronic manic-depressive psychosis.

Optimum therapeutic plasma concentration of Lithium

0.3 –1.3 mmol/l