Fluid, Electrolyte, Acid, and Base Homeostasis Vocabulary Flashcards

Vocabulary practice flashcards covering fluid compartments, electrolyte imbalances, and acid-base disorders based on Chapter 4 lecture notes.

Fluid and Electrolyte Balance

The process of regulating extracellular fluid volume, body fluid osmolality, and plasma concentrations of electrolytes through the interplay of intake, absorption, distribution, and excretion to maintain homeostasis.

Acid-Base Balance

The process of regulating the $\text{pH}$, bicarbonate ($HCO_3^-$) concentration, and partial pressure of carbon dioxide ($PCO_2$) of body fluids.

Acid

A substance that releases hydrogen ions ($H^+$).

Base

A substance that takes up hydrogen ions ($H^+$), with bicarbonate ($HCO_3^-$) being the most important base in the body.

Total Body Water Distribution

Total body water accounts for $60\%$ of body weight, divided into intracellular water ($40\%$ of body weight) and extracellular water ($20\%$ of body weight, comprising interstitial, plasma, and transcellular fluids).

Diffusion

A passive transport process in which solutes move across a membrane from an area of higher concentration to an area of lower concentration without consuming energy.

Osmosis

The passive movement of water through a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.

Osmolality

The concentration of particles in a solution that determines the direction of water movement, with extracellular sodium being its primary determinant.

Hydrostatic Pressure

Fluid pressure exerted against the walls of a container or capillary vessel.

Capillary Osmotic Pressure

Pressure generated by plasma proteins that pulls fluid from the interstitial space back into capillaries.

Facilitated Diffusion

Non-energy-dependent movement of substances across a cell membrane down their concentration gradient using transport proteins.

Active Transport

Energy-dependent ($\text{ATP}$) movement of substances across a cell membrane against their concentration gradient, exemplified by the $Na^+/K^+$ ATPase pump.

Tonicity

A solution's ability to influence water movement into or out of cells, determined by solutes that cannot cross the semipermeable cell membrane.

Isotonic Solution

A solution that creates no net water movement across cell membranes, allowing cells to maintain their original size.

Hypotonic Solution

A solution with a lower solute concentration than cellular fluid, causing water to move into cells and leading to cellular swelling.

Hypertonic Solution

A solution with a higher solute concentration than cellular fluid, causing water to move out of cells and leading to cellular shrinkage.

Serum Sodium ($Na^+$)

The primary extracellular electrolyte that controls water distribution, with a normal serum reference range of $135\text{ to } 145\,\text{mEq/L}$.

Serum Potassium ($K^+$)

The main intracellular electrolyte that determines intracellular osmolality and enables nerve impulse transmission and muscle contraction, with a normal serum range of $3.5\text{ to } 5.0\,\text{mEq/L}$.

Total Serum Calcium ($Ca^{2+}$)

Laboratory measurement representing both bound and unbound calcium in the blood, with a normal reference range of $8.5\text{ to } 10.5\,\text{mg/dL}$.

Ionized Serum Calcium

The unbound, physiologically active form of calcium in the blood, with a normal reference range of $4.65\text{ to } 5.25\,\text{mEq/L}$.

Total Serum Magnesium

An essential electrolyte for $\text{ATP}$ production, protein/DNA synthesis, and nerve conduction, with a normal total serum range of $1.5\text{ to } 2.55\,\text{mg/dL}$.

Serum Phosphorus ($PO_4^-$)

A vital mineral stored mainly in bones and teeth that regulates skeletal development and $\text{ATP}$ formation, with normal adult levels of $2.5\text{ to } 4.5\,\text{mEq/L}$ and infant levels of $4.3\text{ to } 9.3\,\text{mg/dL}$.

Carbonic Acid-Bicarbonate System

The primary physiological chemical buffer system that acts immediately to minimize $\text{pH}$ changes by binding or releasing hydrogen ions ($H^+$).

Respiratory System (in Acid-Base Regulation)

The secondary acid-base response system that controls carbonic acid levels by eliminating or retaining carbon dioxide ($CO_2$) through changes in breathing rate and depth.

Renal System (in Acid-Base Regulation)

The long-term, third line of defense for acid-base balance that excretes hydrogen ions ($H^+$) in urine and reabsorbs or generates new bicarbonate ($HCO_3^-$).

Fluid Volume Depletion

A sustained loss of both sodium and water leading to a decrease in extracellular fluid volume, which can cause hypovolemia, circulatory collapse, and shock.

Dehydration

A hypertonic loss of water only (without proportionate sodium loss) that results in cellular dehydration.

0.9% NaCl (Normal Saline)

An isotonic crystalloid intravenous solution used as the initial fluid of choice for intravascular volume replacement and the only solution compatible with blood product administration.

Lactated Ringer's (LR)

An isotonic crystalloid solution containing multiple electrolytes and lactate, utilized to restore vascular volume and reduce acid-base imbalances.

Packed Red Blood Cells (pRBCs)

A blood component product indicated to increase oxygen-carrying capacity and maintain hemoglobin levels in severe anemia or acute blood loss of up to $25\%$ volume.

Fluid Volume Excess (FVE)

An isotonic expansion of the extracellular fluid compartment (hypervolemia) involving both interstitial and intravascular spaces due to proportionate sodium and water retention.

Edema

Palpable swelling caused by an abnormal increase in interstitial fluid volume.

Hyponatremia

A serum sodium level less than $135\,\text{mEq/L}$, leading to extracellular hypo-osmolality, cellular swelling, and neurological symptoms secondary to cerebral edema.

Hypernatremia

A serum sodium level greater than $145\,\text{mEq/L}$, creating a hyperosmotic state primarily caused by net water loss that pulls water out of cells and leads to cellular dehydration.

Hypokalemia

A serum potassium level less than $3.5\,\text{mEq/L}$, which manifests as muscle weakness, fatigue, decreased GI motility, and potentially fatal cardiac dysrhythmias or respiratory arrest when severe ($< 2.5\,\text{mEq/L}$).

Hyperkalemia

A serum potassium level greater than $5.0\,\text{mEq/L}$, which causes decreased neuromuscular excitability, characteristic ECG changes (tall peaked T waves, widened QRS), and risk of cardiac arrest.

Hypocalcemia

A total serum calcium level less than $8.5\,\text{mg/dL}$ or ionized calcium less than $4.65\,\text{mEq/L}$, characterized by increased neuromuscular excitability, tetany, prolonged QT interval, and positive Trousseau and Chvostek signs.

Tetany

The hallmark clinical manifestation of severe hypocalcemia (serum ionized calcium $< 4.3\,\text{mg/dL}$) characterized by involuntary muscle spasms and neuromuscular hyperexcitability.

Hypercalcemia

A total serum calcium level greater than $10.5\,\text{mg/dL}$, most commonly caused by hyperparathyroidism or malignancy, presenting with muscle weakness, altered mental status, polyuria, and kidney stones.

Hypomagnesemia

A serum magnesium level less than $1.5\,\text{mg/dL}$ (symptomatic usually below $1.0\,\text{mg/dL}$), resulting in neuromuscular hyperexcitability, hyperreflexia, tremors, tetany, and cardiac abnormalities.

Hypermagnesemia

An elevated serum magnesium level that depresses the central nervous system and blocks neuromuscular transmission, presenting early with diminished deep tendon reflexes, flushing, hypotension, and potential cardiac arrest ($> 12\,\text{mg/dL}$).

Hypophosphatemia

An abnormally low serum phosphate level, commonly caused by alcohol use disorder, sepsis, trauma, or respiratory alkalosis, leading to cellular energy failure due to ATP depletion.

Hyperphosphatemia

An elevated serum phosphate level most frequently caused by acute or chronic renal failure due to impaired excretion by the kidneys.

Metabolic Acidosis

An acid-base disorder defined by a low $\text{pH}$ ($< 7.35$) and low bicarbonate ($< 22\,\text{mEq/L}$), caused by hydrogen ion accumulation or bicarbonate loss, compensated by Kussmaul respirations.

Metabolic Alkalosis

An acid-base disorder defined by a high $\text{pH}$ ($> 7.45$) and elevated bicarbonate, caused by hydrogen ion loss (e.g., severe vomiting or NG suctioning) or excessive antacid ingestion.

Respiratory Acidosis

An acid-base disorder resulting from impaired alveolar ventilation, leading to hypercapnia ($PCO_2 > 45\,\text{mm\,Hg}$) and a decreased arterial $\text{pH}$ ($< 7.35$).

Respiratory Alkalosis

An acid-base disorder caused by alveolar hyperventilation, resulting in hypocapnia ($PCO_2 < 35\,\text{mm\,Hg}$) and an elevated arterial $\text{pH}$ ($> 7.45$).