OSMT (Ontario Society of Medical Technologists) Practice Exam

Which plasma protein helps maintain blood volume by pulling tissue fluid into capillaries?

1. Prothrombin

2. Albumin

3. Gamma globulin

4. Haemoglobin

The correct answer is: Albumin

Albumin plays a crucial role in maintaining blood volume and osmotic pressure within the circulatory system. It is a type of plasma protein that is primarily synthesized by the liver. One of its key functions is to help regulate the oncotic pressure, which is the pressure exerted by proteins in the blood plasma that draws water into the circulatory system from surrounding tissues. When there is an adequate concentration of albumin in the blood, it effectively pulls tissue fluid back into the blood vessels, mitigating the risk of edema and ensuring that there is sufficient blood volume to support overall circulatory function. This is particularly important in maintaining blood pressure and proper nutrient and waste exchange in the capillaries. Other proteins mentioned, such as prothrombin, play roles in blood coagulation, gamma globulin is primarily involved in immune function, and hemoglobin's primary function is to carry oxygen in red blood cells. Hence, none of those options contribute to the maintenance of blood volume through the regulation of tissue fluid movement as effectively as albumin does.