Fluid and Electrolyte Imbalance Vocabulary

A complete collection of vocabulary definitions covering body fluid compartments, pressure forces, tonicity, electrolyte imbalances, fluid homeostasis, and clinical considerations.

Intracellular Fluid (ICF)

Body fluid located within each cell, comprising the majority of Total Body Water.

Extracellular Fluid (ECF)

Body fluid located mostly within the bloodstream outside of the cells.

Interstitial Fluid (ISF)

Fluid located in the tissue spaces between the cells and the bloodstream.

Transcellular Compartments

Also known as the 'Third Space,' areas where fluid can become trapped, including the peritoneal cavity, pleural cavity, synovial fluid in joints, and pericardial sac.

Hydrostatic Pressure

The pushing force exerted by fluid in the bloodstream against vessel walls that pushes water through capillaries into the ISF and ICF, generated by the heart's pumping action.

Osmotic Pressure

A force exerted by solutes in a solution that pulls water into the bloodstream from the ICF and ISF.

Oncotic Pressure

Also referred to as colloid pressure, it is the pulling force exerted specifically by plasma proteins like albumin to retain water inside the blood vessels.

Osmolality

The concentration of solutes per $1\,\text{kg}$ of water (weight of solution), used to evaluate body hydration status.

Osmolarity

The concentration of solutes per $1\,\text{L}$ of solution (volume of solution).

Starling's Law

The physiological principle that two opposing forces (hydrostatic pressure and osmotic pressure) balance each other out at capillary membranes to maintain fluid homeostasis.

Albumin

The main colloidal protein produced by the liver that attracts water and keeps fluid within the vascular space.

Tonicity

The solute concentration of an IV solution relative to the bloodstream, determining its effect on cell volume (whether cells remain unchanged, swell, or shrink).

Isotonic Solution

An IV solution with a sodium concentration equal to the patient's blood that causes no change in cell size (e.g., $0.9\%$ Normal Saline, Lactated Ringer's).

Hypotonic Solution

An IV solution with a lower solute concentration than the patient's blood, causing fluid to shift from ECF into ICF and cells to swell (e.g., $0.45\%$ NaCl or $1/2$ NS).

Hypertonic Solution

An IV solution with a higher solute concentration than the patient's blood, causing fluid to shift from ICF into ECF and cells to shrink (e.g., $3\%$ NaCl, D5NS, D10%NS).

Diffusion

The passive movement of solutes or particles from an area of higher concentration to lower concentration across a semi-permeable membrane.

Facilitated Diffusion

Passive transport of specific molecules across a membrane using carrier proteins without requiring energy (e.g., glucose transport via insulin).

Active Transport

The process requiring cellular energy to move a substance across a plasma membrane against a concentration gradient (e.g., the $\text{Na}^+/\text{K}^+$ pump).

Hyponatremia

A serum sodium level lower than $135\,\text{mEq/L}$,

presenting primarily with neurological symptoms such as confusion, headache, seizures, and muscle twitching.

• fluid excess

• Na loss like burns swelling, diarrhea

• elderly

Hypernatremia

A serum sodium level greater than $145\,\text{mEq/L}$,

presenting with signs of dehydration, thirst, altered mental status, tachycardia, and dry mucous membrane

• fluid loss

• THIRSTY

Hypokalemia

A serum potassium level below $3.5\,\text{mEq/L}$,

causing cardiac arrhythmias, muscle cramps, weakness, flattened T waves, and prominent U waves on ECG.

• due to excess loss like vomit, decreased intake

Hyperkalemia

A serum potassium level above 5.2

• due to excess intake, less excretion

• renal disease

• causing muscle twitching, diarrhea, cardiac arrhythmias, tall peaked T waves on ECG, and risk of cardiac arrest.

Sodium Polystyrene Sulfonate (Kayexalate)

A medication used to treat hyperkalemia by promoting potassium excretion through the feces.

Inverse Calcium-Phosphate Relationship

The inverse biological balance between calcium and phosphate levels where high serum calcium results in low serum phosphate, and vice versa.

Antidiuretic Hormone (ADH)

A hormone secreted by the posterior pituitary gland that conserves water at the nephron and stimulates the brain's thirst center.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormonal pathway activated by hypovolemia or low blood pressure that increases renal sodium and water reabsorption to raise blood volume and blood pressure.

Atrial Natriuretic Peptide (ANP)

A hormone released by the heart's atrial chambers in response to excess ECF volume to promote renal excretion of sodium and water.

Brain Natriuretic Peptide (BNP)

A peptide released by the heart's ventricles and brain in response to fluid volume overload to induce natural diuresis.

Edema

The accumulation of excess fluid in the interstitial space caused by increased hydrostatic pressure, reduced colloidal pressure (ascites) , increased capillary permeability (albumin leaks into ICS) , or obstructed lymphatic drainage.

Shock

A life-threatening state defined as the failure of blood vessels to supply tissues and organs with adequate blood flow.

Sodium look for

neuro, confusion, seizures

potassium look for

heart and muscles think arrhyrthmias

calcium think of

muscle and bone spasm vs stone

Blood clotting​

- Muscle contraction​

- Formation of bones and teeth​

magnesium think of

reflexes and muscles

• hyper = decreased reflexes

• hypo = increased reflexed

Requirement for many cellular metabolic processes, such as functioning of nerve conduction, replication and transcription of DNA, translation of RNA, intracellular enzyme reactions, and all processes that require ATP.

Cardiovascular System: Required for vasodilation and normal functioning.

phosphorus is opposite of calcium and

Essential component of bone, red blood cells, enzymatic processes​

- Assists with formation of adenosine triphosphate (ATP)​

- Helps regulate acid-base balance and cellular building blocks​

Baroreceptors

in the walls of the large arteries they stretch and shrink depending on fluid volume to increase or decrease BP and volume

Osmoreceptors

these detect changes in osmotic pressure, they stimulate our thirst in the hypothalamus

Hormonal​

• ADH is antidiretic, this holds onto our urine and stimulates thirst ​

• Renin angiotension stimulated by low BP naturally ​

• Natrieutic is wayyy too much fluid ​ANP, BNP, CNP

ANP

heart’s atrial chambers

Brain natriuretic peptide (BNP)

heart’s ventricles and brain

when a pt has high bnp the excess fluid is giving STRESS ​

• Stress on the heart is also CHF, cannot get rid of stuff ​

• Fluid basically everywhere so it is normally like infection​

• Fluid overload basically ​

• Weigh the patients ​

C-type natriuretic peptide (CNP)

produced by endothelial cells ofthe arteries and ventricular cells of the heart.