Chapter 18.2, Problem 10AYLO

Summary Introduction

To discuss:

The conditions of excess and deficient RBC counts, and their forms, causes, and pathological consequences.

Introduction:

The body is endowed with mechanisms to detect changes in its internal environment, to antagonize the changes, and to ultimately maintain a fairly constant internal environment. These mechanisms together are as termed homeostasis – the maintenance of a constant internal environment.

The number of RBCs in the blood is maintained at a constant level by a balance between the supply of new RBCs by erythropoiesis and RBC death and degradation, which happens around their 120-day life. An imbalance of supply and degradation leads to either an excess or a shortage of RBCs. A deficiency in the number of RBCs in the blood is termed as anemia, whereas an excess is known as polycythemia.