Concepts of Fluid and Electrolyte Balance

These flashcards cover key vocabulary related to the concepts of fluid and electrolyte balance essential for understanding physiology and pathophysiology.

Fluid Balance

The regulation of body fluid volume and composition to maintain homeostasis.

Electrolyte

Dissolved substances that express an electrical charge, essential for nerve impulse transmission and muscle contraction.

Filtration

Movement of fluid through a membrane due to differences in hydrostatic pressure.

Diffusion

Movement of solute particles across a permeable membrane from higher to lower concentration.

Osmosis

Movement of water through a selectively permeable membrane to equalize osmolarity between two compartments.

Hyponatremia

A condition where serum sodium levels fall below 136 mEq/L, leading to less excitability of membranes.

Hypernatremia

A condition where serum sodium levels exceed 145 mEq/L, causing increased excitability of tissues.

Hypokalemia

A serum potassium level below 3.5 mEq/L, leading to muscle weakness and increased risk of cardiac issues.

Hyperkalemia

A serum potassium level above 5.5 mEq/L, causing muscle excitability and potential cardiac complications.

Hypocalcemia

A condition where serum calcium levels fall below 9.0 mg/dL, impacting muscle and nerve function.

Hypercalcemia

A serum calcium level above 10.5 mg/dL, which can decrease excitability of muscles and nerves.

Hypomagnesemia

A condition with serum magnesium levels below 1.3 MEQ/L, leading to increased nerve excitability.

Hypermagnesemia

A condition with serum magnesium levels above 2.1 MEQ/L, resulting in muscle weakness and bradycardia.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormonal system that regulates blood pressure and fluid balance within the body.

ADH (Antidiuretic Hormone)

A hormone released in response to changes in blood osmolarity that promotes water retention.

Fluid Balance

The regulation of body fluid volume and composition to maintain homeostasis.

Electrolyte

Dissolved substances that express an electrical charge, essential for nerve impulse transmission and muscle contraction.

Filtration

Movement of fluid through a membrane due to differences in hydrostatic pressure.

Diffusion

Movement of solute particles across a permeable membrane from higher to lower concentration.

Osmosis

Movement of water through a selectively permeable membrane to equalize osmolarity between two compartments.

Aldosterone

A hormone secreted by the adrenal cortex that promotes sodium and water reabsorption and potassium excretion in the kidneys.

ANP (Atrial Natriuretic Peptide)

A hormone released by the heart in response to increased blood volume; it increases sodium excretion and inhibits ADH.

Focused Fluid Assessment

Nursing evaluations including skin turgor, mucous membrane moisture, edema, vital signs (BP and HR), and strict intake/output (I/O) monitoring.

Laboratory Findings: BUN & Creatinine

BUN (10 - 20 \text{ mg/dL}) and Creatinine (0.6 - 1.2 \text{ mg/dL}) assess renal function; elevated BUN can also indicate dehydration.

Serum Osmolality

A measure of the concentration of particles in the blood; normal range is approximately 275 - 295 \text{ mOsm/kg}.

Isotonic Solutions

Solutions with an osmolarity similar to plasma (270 - 300 \text{ mOsm/L}) that do not cause fluid shifts between compartments (e.g., 0.9\% NS, LR).

Hypotonic Solutions

Solutions with an osmolarity lower than plasma (< 270 \text{ mOsm/L}); fluid moves from the vascular space into the cells (e.g., 0.45\% NS).

Hypertonic Solutions

Solutions with an osmolarity higher than plasma (> 300 \text{ mOsm/L}); fluid is drawn out of the cells into the vascular space (e.g., 3\% NS, D5NS, D5LR).

Normal Saline (0.9\% NS)

An isotonic solution used for general fluid replacement and to increase vascular volume.

Lactated Ringer’s (LR)

An isotonic solution containing multiple electrolytes, often used for surgical patients or burn victims to replace fluid and buffer pH.

5% Dextrose in Water (D5W)

Physiologically hypotonic; provides free water once dextrose is metabolized and can be used for hydration.

Furosemide (Lasix)

A loop diuretic used to treat hypervolemia (fluid overload) by promoting the excretion of sodium and water.

Spironolactone (Aldactone)

A potassium-sparing diuretic that antagonizes aldosterone to promote water loss while retaining potassium.

Sodium Polystyrene Sulfonate (Kayexalate)

A medication used to treat hyperkalemia by exchanging sodium for potassium in the intestinal tract for excretion.

Hyponatremia

A condition where serum sodium levels fall below 136 \text{ mEq/L}, leading to less excitability of membranes.

Hypernatremia

A condition where serum sodium levels exceed 145 \text{ mEq/L}, causing increased excitability of tissues.

Hypokalemia

A serum potassium level below 3.5 \text{ mEq/L}, leading to muscle weakness and increased risk of cardiac issues.

Hyperkalemia

A serum potassium level above 5.5 \text{ mEq/L}, causing muscle excitability and potential cardiac complications.

Hypocalcemia

A condition where serum calcium levels fall below 9.0 \text{ mg/dL}, impacting muscle and nerve function.

Hypercalcemia

A serum calcium level above 10.5 \text{ mg/dL}, which can decrease excitability of muscles and nerves.

Hypomagnesemia

A condition with serum magnesium levels below 1.3 \text{ mEq/L}, leading to increased nerve excitability.

Hypermagnesemia

A condition with serum magnesium levels above 2.1 \text{ mEq/L}, resulting in muscle weakness and bradycardia.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormonal system that regulates blood pressure and fluid balance within the body.

ADH (Antidiuretic Hormone)

A hormone released in response to changes in blood osmolarity that promotes water retention.