Fluid, Electrolyte, and Acid-Base Balance Vocabulary

Vocabulary practice flashcards covering fluid compartments, transport mechanisms, tonicity, fluid regulatory systems (RAAS, ADH, Natriuretic Peptides), fluid imbalances, effusions, and electrolyte disorders based on the lecture notes.

Intracellular Fluid (ICF)

The fluid compartment located inside cells, constituting approximately $40\%$ of total body weight.

Hydrostatic Pressure

The pushing force exerted by fluid/water pressure within the bloodstream that moves water out of capillaries into the interstitial fluid (ISF) and intracellular fluid (ICF).

Diffusion

The passive transport mechanism where molecules, typically water and electrolytes, move from an area of high concentration to an area of low concentration.

Osmosis

The movement of water across a membrane following solutes.

Facilitated Transport

The passage of molecules across a membrane with the assistance of a carrier protein, such as glucose requiring insulin.

Active Transport

The movement of substances across a concentration gradient from low to high concentration, requiring energy (ATP), such as the sodium-potassium pump.

Isotonic Solution

An intravenous solution with the same tonicity as blood that causes no fluid shifts but increases blood volume (e.g., $0.9\%$ NaCl, Lactated Ringer's, $D_5W$).

Hypotonic Solution

An intravenous solution with a lower solute concentration than blood, causing fluid to move into cells so they swell; used as a treatment for dehydration (e.g., $0.45\%$ NaCl).

Hypertonic Solution

An intravenous solution with a higher solute concentration than blood, causing fluid to leave cells and shrink them, which helps reduce edema (e.g., $3\%$ NaCl, IV mannitol, $D_{10}W$).

Renin-Angiotensin-Aldosterone System (RAAS)

A compensatory cascade triggered by kidney secretion of renin in response to hypovolemia, hypotension, dehydration, or low cardiac output to increase blood volume and blood pressure.

Aldosterone

A steroid hormone secreted by the adrenal gland that increases sodium and water reabsorption into the bloodstream and promotes potassium excretion into the urine.

Oncotic Pressure

The osmotic pressure exerted specifically by proteins, mainly albumin, that pulls fluid out of tissues and into venous capillaries.

Osmolality

The concentration of solute particles per kilogram of solution.

Osmolarity

The number of osmoles of solute per liter of solution.

Anti-Diuretic Hormone (ADH)

A hormone released by the posterior pituitary gland that promotes water reabsorption in the collecting ducts of the kidneys to normalize elevated plasma concentration.

Osmoreceptors

Sensory receptors that detect plasma concentration (normal baseline around $290\,\text{mOsm}$) and trigger thirst and ADH release when plasma concentration increases.

Natriuretic Peptides

Hormones produced by the heart (ANP, BNP, CNP) in response to excessive blood volume that promote the excretion of fluid and sodium.

Atrial Natriuretic Peptide (ANP)

A natriuretic peptide synthesized and released by atrial cells when they are stretched by fluid overload.

Brain Natriuretic Peptide (BNP)

A natriuretic peptide produced primarily by the heart's ventricles (and to a lesser extent the brain) in response to increased ventricular volume.

Edema

The excessive accumulation of fluid in the interstitial fluid (ISF) and intracellular fluid (ICF) compartments.

Dependent Edema

Fluid buildup in the lower extremities (feet and ankles) resulting from venous blood pooling due to gravity.

Pitting Edema

A form of edema where visible indentation remains after pressure is applied to the swollen tissue, graded on a scale from +1 to +3.

Sequestered Fluid (Third Space Accumulation)

Fluid trapped outside the vascular system that cannot circulate effectively, leading to decreased blood volume and blood pressure (e.g., ascites, pleural effusion, severe burns).

Effusion

An abnormal accumulation of fluid within a anatomical body cavity, such as the pleural cavity (lungs), pericardial sac, or abdominal cavity (ascites).

Transudate

A clear fluid effusion resulting from hydrostatic or osmotic fluid balance issues rather than inflammatory processes.

Exudate

A cloudy or dense fluid effusion rich in protein, white blood cells, and cellular debris caused by inflammation, injury, or increased vascular permeability.

Hyponatremia

A serum sodium concentration below normal levels ($< 135\,\text{mEq/L}$), presenting with symptoms like headache, confusion, lethargy, muscle cramps, and potential cerebral edema.

Hypernatremia

A serum sodium concentration above normal levels ($> 145\,\text{mEq/L}$), leading to cellular dehydration, neuron shrinkage, and altered electrical firing.

Hyperkalemia

An elevated serum potassium level ($> 5.2\,\text{mmol/L}$) often caused by low renal perfusion, which can produce numbness, muscle cramps, diarrhea, characteristic ECG changes (peaked T waves, sine wave pattern), and cardiac arrest.

Hypokalemia

A low serum potassium level ($< 3.5\,\text{mmol/L}$) caused by renal losses, alkalosis, or GI fluid loss, presenting with anorexia, cardiac arrhythmias, muscle cramps, and prominent U waves on an ECG.

Chvostek's Sign

A clinical sign of hypocalcemia elicited by tapping the facial nerve, causing twitching of the facial muscles.

Trousseau's Sign

A clinical sign of hypocalcemia characterized by carpopedal spasm induced by inflating a blood pressure cuff above systolic pressure.

Oliguria

A condition defined as urine output of less than $400\,\text{mL/day}$, indicating potential renal dysfunction.