Fluid and Electrolyte Balance - Anatomy and Physiology
- Why is severe hyperkalemia dangerous?
- It depolarizes resting membrane potentials, disrupting cardiac conduction and causing arrhythmias that can lead to cardiac arrest.
- What is the major cation of the intracellular fluid?
- Potassium (K+).
- An athlete sweats heavily for hours and replaces the loss only with large amounts of plain water. Which electrolyte disturbance is most likely?
- Hyponatremia. Sweat removes Na+, and drinking plain water dilutes the Na+ that remains.
- What is the major cation of the extracellular fluid?
- Sodium (Na+). It is the main determinant of ECF osmolarity and volume.
- What is the main stimulus for thirst?
- A rise in plasma osmolality detected by hypothalamic osmoreceptors; a fall in blood volume or pressure also stimulates thirst.
- Why does severe hyponatremia cause confusion and seizures?
- Low ECF osmolarity draws water into cells, so brain cells swell (cerebral edema).
- What is the major anion of the extracellular fluid?
- Chloride (Cl-), which usually follows Na+.
- What is the normal range of serum sodium?
- About 135 to 145 mEq/L.
- What is the normal range of serum potassium?
- About 3.5 to 5.0 mEq/L.
- What is insensible water loss?
- Water lost by evaporation from the skin and the respiratory tract, which a person does not notice and cannot easily control.
- What is the major inorganic anion of the intracellular fluid?
- Phosphate (). Negatively charged proteins are also abundant inside cells.
- Which hormone, released by atrial muscle cells in response to stretch, promotes renal excretion of Na+ and water?
- Atrial natriuretic peptide (ANP).