The Cellular Environment: Fluids and Electrolytes - Vocabulary Flashcards (Video Notes)

Vocabulary flashcards covering key fluid and electrolyte concepts from the lecture notes.

Total body water (TBW)

The total amount of water in the body, comprising all fluid compartments (ICF + ECF).

Intracellular fluid (ICF)

Fluid contained inside the body's cells.

Extracellular fluid (ECF)

Fluid outside the cells, including plasma and interstitial fluid.

Interstitial fluid

Fluid between cells in tissues.

Intravascular fluid

Plasma within blood vessels.

Cerebrospinal fluid (CSF)

Fluid surrounding the brain and spinal cord.

Osmolarity

Concentration of solutes per liter of solution; used to describe fluids outside the body.

Osmolality

Concentration of solutes per kilogram of water; used to describe fluids inside the body.

Capillary hydrostatic pressure

Blood pressure in capillaries that tends to push fluid out into the interstitial space.

Capillary oncotic pressure

Osmotic pressure due to plasma proteins (mainly albumin) that pulls water into capillaries.

Interstitial hydrostatic pressure

Pressure in the interstitial space that tends to push water into capillaries.

Interstitial oncotic pressure

Osmotic pressure in the interstitial space that draws water out of capillaries.

Filtration

Movement of fluid from capillaries into the interstitial space driven by hydrostatic/oncotic forces.

Reabsorption

Movement of fluid from the interstitial space back into capillaries due to oncotic pressure.

Edema

Accumulation of fluid in the interstitial spaces.

Hypovolemia

Extracellular fluid volume deficit; decreased circulating blood volume.

Hypervolemia

Extracellular fluid volume excess; fluid overload.

Osmotic pressure

Pressure generated by solutes that drives water movement across membranes.

Oncotic pressure

Colloid osmotic pressure mainly from plasma proteins that draws water into vessels.

Antidiuretic hormone (ADH, vasopressin)

Hormone that increases water reabsorption in the kidneys; released with high osmolality or low volume.

Aldosterone

Hormone that increases sodium reabsorption and promotes potassium and hydrogen ion excretion, increasing ECF volume.

Renin-angiotensin-aldosterone system (RAAS)

Hormonal cascade regulating blood pressure and Na+/water balance.

Natriuretic peptides (ANP, BNP)

Peptides that oppose RAAS by promoting natriuresis and diuresis.

Isotonic solution

Fluid with osmolality similar to body fluids; no net water movement.

Hypertonic solution

Fluid with higher osmolality than body fluids; draws water out of cells.

Hypotonic solution

Fluid with lower osmolality; water moves into cells.

Hyponatremia

Serum sodium < 135 mEq/L; low osmolality with risk of cellular swelling, especially in brain.

Hypernatremia

Serum sodium > 145 mEq/L; hyperosmolar state with cellular dehydration.

Hyperchloremia

Serum chloride > 106 mEq/L; often occurs with hypernatremia or bicarbonate deficit.

Hypochloremia

Serum chloride < 98 mEq/L; often with hyponatremia or elevated bicarbonate.

Sodium balance

Sodium as the primary extracellular cation that regulates osmotic forces; controlled by aldosterone and natriuretic peptides.

Potassium

Major intracellular cation; essential for nerve impulses, heart rhythm, and muscle contraction; normal ECF 3.5–5.0 mEq/L.

Hypokalemia

Potassium < 3.5 mEq/L; causes include reduced intake, cellular shift, or increased loss; can cause dysrhythmias.

Hyperkalemia

Potassium > 5.0 mEq/L; causes include increased intake, shifts from ICF to ECF, or reduced excretion; risk of dysrhythmias.

Calcium

Regulated by PTH, vitamin D, and calcitonin; essential for bones, clotting, and muscle contraction; ionized Ca 5.5–5.6 mg/dL.

Hypocalcemia

Calcium < 9.0 mg/dL; signs include neuromuscular excitability and Chvostek/Trousseau signs.

Hypercalcemia

Calcium > 10.5 mg/dL; causes include hyperparathyroidism and malignancy; symptoms include weakness and kidney stones.

Phosphate

Serum phosphate 2.5–4.5 mg/dL; mostly stored in bone; inversely related to calcium.

Hypophosphatemia

Phosphate < 2.0 mg/dL; causes include malabsorption and vitamin D deficiency; can cause osteomalacia and weakness.

Hyperphosphatemia

Phosphate > 4.5 mg/dL; causes include renal failure and certain therapies; can lead to tissue calcifications.

Magnesium

Normal plasma Mg 1.5–3.0 mg/dL; stored in muscle/bone; interacts with calcium and affects neuromuscular excitability.

Hypomagnesemia

Low Mg; can cause neuromuscular irritability, tetany, and seizures; often with hypocalcemia/hypokalemia.

Hypermagnesemia

High Mg; often due to renal failure; causes muscle weakness and respiratory depression.

Ascites

Third-spacing of fluid into the peritoneal cavity, often from portal hypertension or low oncotic pressure.

Third spacing

Fluid shifts into nonfunctional spaces (e.g., peritoneal, pleural) beyond normal compartments.

Edema treatment

Strategies to reduce edema: elevate limbs, compression, limit salt, and use diuretics.