Anesthesia Technician Practice Exam

What characteristic differentiates colloids from crystalloids?

1. Colloids are smaller particles

2. Colloids do not remain in the intravascular space

3. Colloids contain larger particles

4. Colloids are isotonic

The correct answer is: Colloids contain larger particles

The distinguishing characteristic of colloids is that they contain larger particles compared to crystalloids. Colloids consist of molecules or particles that are typically larger than those found in crystalloids, which usually consist of small ions or molecules dissolved in a solution. Because of their larger size, colloids have the ability to create an oncotic pressure that helps to retain fluid within the intravascular space, making them effective for volume expansion in conditions where fluid loss occurs. In contrast, crystalloids can easily pass through semipermeable membranes and may not effectively remain within the vascular compartment as they often diffuse into interstitial spaces. This characteristic makes colloids particularly useful in specific clinical scenarios, such as in treating patients needing rapid plasma volume expansion. Additionally, while both colloids and crystalloids can be isotonic, this property does not serve as the primary differentiator. The presence of larger particles in colloids is central to their function and use in medical treatments compared to the smaller particles found in crystalloids.