Fluid and Electrolytes - Vocabulary Flashcards (Video Notes)

A set of vocabulary-style flashcards covering core concepts from the lecture notes on fluids, electrolytes, acid-base balance, and related physiology.

Total Body Water (TBW)

Sum of all water in the body; intracellular fluid (ICF) makes up ~2/3 of TBW and extracellular fluid (ECF) ~1/3.

Intracellular Fluid (ICF)

Fluid located inside cells; accounts for about two-thirds of total body water.

Extracellular Fluid (ECF)

Fluid outside cells; about one-third of TBW; subdivides into intravascular (plasma) and interstitial fluid.

Intravascular Fluid

Blood plasma; part of the extracellular fluid within the vascular system.

Interstitial Fluid

Fluid in the spaces between cells; part of the extracellular fluid.

Transcellular Fluid

Small, specialized fluid compartments (e.g., intestinal, cerebrospinal, intraocular, etc.).

Isotonic Solution

Solution with an equal solute concentration to plasma; water movement between compartments is minimal.

Hypotonic Solution

Solution with lower solute concentration than plasma; water moves into cells.

Hypertonic Solution

Solution with higher solute concentration than plasma; water moves out of cells.

Diffusion

Movement of particles from an area of higher concentration to lower concentration until evenly distributed.

Hydrostatic Pressure

Capillary pressure that pushes fluid out into the interstitial space; higher in capillaries than surrounding tissue.

Oncotic (Osmotic) Pressure

Pressure pulling fluid into capillaries, mainly due to plasma proteins (e.g., albumin).

Net Filtration

Balance of forces favoring filtration vs. reabsorption across the capillary wall (Starling’s forces).

Starling’s Law

Principle describing fluid movement across capillaries based on hydrostatic and oncotic pressures.

RAAS (Renin-Angiotensin-Aldosterone System)

Hormonal system activated by low blood volume/pressure; causes vasoconstriction and Na+/water retention, increasing fluid volume.

Renin

Enzyme released by the kidneys that converts angiotensinogen to angiotensin I.

Angiotensinogen

Liver-produced protein that is cleaved by renin to form angiotensin I.

ACE (Angiotensin-Converting Enzyme)

Enzyme that converts angiotensin I to angiotensin II; primarily in the lungs.

Angiotensin II

Potent vasoconstrictor that stimulates aldosterone release and raises blood pressure and volume.

Aldosterone

Mineralocorticoid from the adrenal cortex; increases Na+ and water reabsorption in the kidneys, expanding fluid volume.

ANP (Atrial Natriuretic Peptide)

Hormone released from atria in response to increased blood volume; promotes Na+ and water excretion and inhibits RAAS.

ADH (Antidiuretic Hormone)

Hormone released by the posterior pituitary in response to high plasma osmolality or low volume; promotes renal water reabsorption and thirst.

Osmolality

Concentration of solutes in body fluids; triggers osmoreceptors and thirst when altered.

Sodium (Na+)

Major extracellular cation; regulates fluid distribution and osmolarity; 135–145 mEq/L in plasma.

Hypernatremia

Serum Na+ >145 mEq/L; often from Na+ gain or water loss; causes intracellular dehydration and thirst, confusion, edema, etc.

Hyponatremia

Serum Na+ <135 mEq/L; from Na+ loss or water gain; water shifts into cells, risking cerebral edema and neurologic symptoms.

Potassium (K+)

Major intracellular cation; 3.5–5.0 mEq/L; required for nerve/muscle function and cardiac rhythm.

Hypokalemia

Potassium <3.5 mEq/L; causes reduced neuromuscular excitability and potential cardiac dysrhythmias.

Hyperkalemia

Potassium >5.5 mEq/L; may cause neuromuscular irritability and cardiac dysrhythmias; ECG changes may occur.

ECG Changes with Potassium

Potassium levels influence ECG: hypokalemia and hyperkalemia produce characteristic waveform changes (e.g., tall peaks in hyperkalemia, flattened T waves in hypokalemia).

Acid-Base Imbalance

Disruption in the body's pH balance; includes acidosis and alkalosis due to respiratory or metabolic causes.

pH

Measure of acidity/alkalinity of the blood; normal arterial range about 7.35–7.45.

Acidosis

Systemic increase in hydrogen ions or decrease in bicarbonate; pH < 7.35.

Alkalosis

Systemic decrease in hydrogen ions or increase in bicarbonate; pH > 7.45.

Carbonic Acid–Bicarbonate Buffer System

Primary chemical buffer; rapid pH regulation via CO2 and HCO3− balance.

Chemical Buffer System

Immediate, first-line buffers that minimize pH changes when acids/bases are added.

Respiratory Compensation

Secondary mechanism; adjusts CO2 excretion/retention to help correct pH; occurs within minutes.

Renal Compensation

Secondary mechanism; kidneys adjust H+ and HCO3− excretion to correct pH; develops over days.

ABG (Arterial Blood Gas)

Test to assess acid-base balance and oxygenation; values include pH, pCO2, HCO3−, pO2, SpO2.

Kussmaul Respiration

Deep, labored breathing pattern often seen in metabolic acidosis as a compensatory mechanism.

Metabolic Acidosis

Acid-base disorder with decreased HCO3− or increased noncarbonic acids; compensatory hyperventilation (Kussmaul).

Metabolic Alkalosis

Alkaline imbalance with increased HCO3− or loss of acids; often due to vomiting or diuretic use; compensatory hypoventilation.

Edema

Accumulation of fluid in interstitial spaces; caused by elevated capillary hydrostatic pressure, reduced plasma oncotic pressure, increased capillary permeability, or lymphatic obstruction.

Ascites

Fluid accumulation in the peritoneal cavity; a form of edema in the abdomen.

Pulmonary Edema

Fluid accumulation in alveoli, impairing gas exchange; often due to increased hydrostatic pressure or decreased oncotic pressure.

Pericardial Effusion

Accumulation of fluid in the pericardial cavity, which can compress the heart.

Fluid Volume Deficit (FVD)

Hypovolemia; insufficient fluid volume due to abnormal losses, decreased intake, or third-spacing.

Fluid Volume Excess (FVE)

Hypervolemia; excess fluid due to excessive intake or impaired excretion, can lead to edema and hypertension.