Biological Systems MCAT Practice Exam

What component of blood serves to maintain osmotic pressure within capillaries?

1. Immunoglobulins

2. Albumin

3. Fibrinogen

4. Electrolytes

The correct answer is: Albumin

The component of blood that serves to maintain osmotic pressure within capillaries is albumin. Albumin is a type of protein produced by the liver and is the most abundant protein found in plasma. It plays a critical role in regulating the oncotic pressure of the blood, which helps keep fluid within the circulatory system and prevents it from leaking into the surrounding tissues. The osmotic pressure created by albumin draws water into the capillaries, counteracting the hydrostatic pressure that tends to push fluid out of them. This balance is essential for maintaining proper fluid distribution in the body and ensuring that tissues receive the nutrients and oxygen they need without becoming overloaded with fluid. Immunoglobulins, while crucial for immune response, primarily function in defense against pathogens and do not have a significant role in maintaining osmotic pressure. Fibrinogen is involved in blood clotting and not in osmoregulation. Electrolytes, though important for many physiological functions, are more associated with the balance of fluids and electrical charges but do not specifically regulate osmotic pressure in the same way that albumin does.