Week 6 Summary

This week, we reviewed the components of the hematologic system that included blood cell and types. Emphasis is placed on understanding the composition of blood and blood products. Blood consists of cells suspended in a solution of about 90 percent water and 10 percent solutes. In adults, the total blood volume is approximately 5.5 L. Plasma, the liquid portion of the blood, contains two major groups of proteins—albumins and globulins. The cellular elements of blood are the erythrocytes (RBCs), leukocytes (WBCs), and platelets (thrombocytes). Erythrocytes are the most abundant cells of the blood, occupying approximately 48 percent of the blood volume in men and approximately 42 percent in women. Erythrocytes are responsible for tissue oxygenation. Your textbook Pathophysiology: The Biologic Basis for Disease in Adults and Children states that leukocytes are fewer in number than erythrocytes and constitute approximately 5,000 to 10,000 cells/mm3 of blood. Leukocytes defend the body against infection and remove dead or injured host cells. Leukocytes are classified as granulocytes (neutrophils, basophils, and eosinophils) or agranulocytes (monocytes, macrophages, and lymphocytes). The neutrophil is the most abundant leukocyte (approximately 55 percent of the leukocytes) and is the primary granulocyte that defends against infections. Lymphocytes are the primary cells of the immune response.

We reviewed erythropoiesis, mechanisms of hemostasis, and clinical evaluation of the hematologic system. In summary, the eosinophil count is high in the first year of life and is higher in children than in adolescents and adults. Monocyte counts are high in the first year of life and then decrease to adult levels. Platelet counts in full-term infants are comparable with those in adults and remain so throughout childhood. Blood composition changes little with age. A delay in erythrocyte replenishment may occur after bleeding, presumably because of iron deficiency. Lymphocyte function appears to decrease with age. Particularly affected is a decrease in cellular immunity. However, platelet adhesiveness probably increases with age.

Alterations in Oxygen Transport

Deb Smith, age fifty-six, came to her nurse practitioner (NP) with fatigue, pallor, dyspnea on exertion, and palpitations. Her laboratory report indicates that her hematocrit, hemoglobin, and reticulocyte counts are low; that her MCV is high; and that her MCH and MCHC are normal. Her diagnosis is pernicious anemia.

Answer the following questions regarding Deb’s anemia and provide the pathophysiology associated with the body’s response to this disease process.

Why should Deb’s NP ask her about paresthesia and ataxia?

Why did her NP prescribe vitamin B12 by intramuscular injection rather than orally?

What causes pernicious anemia?

What are the technical terms that describe an anemia with high MCV and normal MCH?