Chapter 1-6: Fluid Balance and IV Fluids Review

Flashcards covering body fluid compartments, osmosis/diffusion, hormonal regulation, tonicity, IV fluids, crystalloids vs colloids, and clinical considerations.

What percent of an average adult's body weight is water?

About 60%.

Two-thirds of body water is in which compartment?

Intracellular fluid (ICF).

One-third of body water is in which compartment?

Extracellular fluid (ECF).

Within extracellular fluid, what are the main components?

Interstitial fluid and plasma (transcellular is a small separate fluid).

What does plasma refer to in the context of blood?

The free water component of blood within vessels.

What is an electrolyte?

A molecule that carries an electric charge (ion).

Inside the cell, the primary cations are?

Potassium and magnesium (phosphate also present).

Outside the cell, the main extracellular cation is?

Sodium (Na+).

Outside the cell, the main extracellular anion is?

Chloride (Cl-).

What are the two broad forces regulating fluid movement across membranes?

Hydrostatic (push) and oncotic/osmotic (pull, mainly due to albumin).

What is oncotic pressure?

The pulling force drawing fluid into the intravascular space, primarily due to albumin.

What happens in hypoalbuminemia?

Lower oncotic pull; more fluid leakage to interstitial space; more free drug distribution.

Which hormone controls water retention and thirst?

Antidiuretic hormone (ADH).

High plasma osmolality typically leads to what response?

Increased thirst (hypothalamus-mediated).

What condition results from ADH excess causing water retention and relative hyponatremia?

Relative hyponatremia (low plasma sodium due to dilution).

What is diabetes insipidus?

Condition of deficient ADH leading to excessive water loss.

What are isotonic, hypotonic, and hypertonic IV fluids?

Solutions with equal, lower, or higher tonicity than plasma, affecting water movement.

What are crystalloids and colloids?

Crystalloids: small molecules that distribute with water; Colloids: larger molecules (e.g., albumin) that raise oncotic pressure.

Give examples of isotonic crystalloids used clinically?

Normal saline (0.9% NaCl) and lactated Ringer's.

What is the effect of isotonic fluids on body compartments?

Add volume without changing cell tonicity or causing net fluid shift.

What is third spacing?

Fluid in the interstitial space not returning to circulation; edema in dependent areas.

Why monitor lung sounds and urine output during IV fluid administration?

To detect fluid overload and assess renal perfusion/volume status.

What happens to cells in hypotonic vs hypertonic solutions?

Hypotonic causes swelling; hypertonic causes shrinking.

Role of sodium in fluid balance?

Sodium is the major extracellular solute; adjusting sodium influences osmolality and water distribution.