Chapter 42, Problem 1PL

Summary Introduction

Introduction:Hematocrit, hemoglobin content, coagulation and cholesterol are the tests commonly used to determine the blood composition. The obtained values are compared with the normal values to identifying various disease conditions.

Answer to Problem 1PL

Correct answer:

The correct answer is option (b) Hematocrit.

Explanation of Solution

Explanation/justification for the correct answer:

Option (b) Hematocrit. The hematocrit is the percentage of blood volume composed of red blood cells. When heparinized blood sample left undisturbed the heavier cellular component settles to the bottom of the tube. The red blood cells settle at the bottom as red layer is called compacted red blood cells. The percentage of compacted red blood cells in the blood sample is called hematocrit.So, the correct answer is option (b).

Explanation for incorrect answer:

Option (a) Hemoglobin. Hemoglobin is responsible for the binding of oxygen in red blood cells. Molecules of the protein hemoglobin compose about one third of the volume within red blood cell. The hemoglobin molecule is composed of four protein subunits, each containing a heme molecule with an atom of iron. Each iron binds to one oxygen molecule. As a result each hemoglobin molecule can bind to four oxygen molecule.So, this is an incorrect option.

Option (c) Buffy coat.When heparinized blood sample left undisturbed the heavier cellular component settles to the bottom of the tube. The red blood cells settle at the bottom as red layer is called compacted red blood cells.A thin, whitish layer known as buffy coat, forms on the top of compacted red blood celllayer. This contains the white blood cells and the platelets. So, this is an incorrect answer.

Option (d) Coagulation.The coagulation mechanism involves a series of chain reaction that results in a blood clot. The final stage of blood clot formation occurs when thrombin converts a soluble plasma protein called fibrinogen into insoluble threads of fibrin. The fibrin mesh traps the cellular components of the blood, stopping the blood loss. So, this is an incorrect answer.