Body Fluid Compartments II

These flashcards cover key concepts related to body fluid compartments, osmolality, and the physiological effects of fluids in the body.

What is osmolality?

Osmolality is the number of free (dissociated) particles in a solution.

What determines the osmolality of extracellular fluid (ECF)?

The majority of ECF osmolality is determined by electrolytes (ions) that dissociate in solution.

What happens to water movement when osmolality increases?

Water moves from low to high solute concentration.

What type of fluid expansion occurs with the ingestion of water?

Hypotonic Expansion.

What is the effect on the intracellular fluid volume during hypertonic expansion?

ICF volume decreases as water moves out to restore osmotic equilibrium.

What occurs during isotonic contraction?

Loss of salt and water in equivalent amounts, decreasing extracellular fluid volume.

What is the formula for calculating total osmotic particles in the body?

Total osmotic particles in the body = (ICFV + ECFV) x osmotic concentration.

What happens to the intracellular fluid volume when there is a loss of water in the ECF?

The intracellular fluid volume decreases and osmolality increases.

What fluid should be administered intravenously if a person cannot drink water?

5% glucose solution, as it behaves like water without causing cell lysis.

What is the reflection coefficient for NaCl and what does it indicate?

NaCl is ‘impermeable’ with a reflection coefficient of 1.0, generating a sustained osmotic effect.

What happens to the plasma osmolality when a man loses more water than salt while sweating?

Plasma osmolality increases because the extracellular fluid volume decreases.

Why can't pure water be infused intravenously?

Infusing pure water can cause cells at the infusion site to swell and burst, releasing potassium into plasma.

What is the consequence of hyperkalemia?

Hyperkalemia can reduce outward diffusion of K+ which depolarizes nerve and muscle, leading to spastic paralysis.

How does glucose infusion affect cell osmotic effects?

Glucose enters cells, takes water with it, and then is incorporated into larger molecules, reducing osmotic effects.

What is the significance of understanding osmotic gradients in body fluids?

Osmotic gradients drive water movement between compartments to maintain equilibrium.