11) In adults, the stem cells responsible for the production of red and white blood cells originate primarily in the

A) liver.

B) thymus.

C) spleen.

D) red bone marrow.

E) yellow bone marrow.

12) The average life span of a red blood cell is about

A) 1 week.

B) 1 month.

C) 4 months.

D) 6 months.

E) 1 year.

13) The function of hemoglobin is to

A) bind and transport oxygen and carbon dioxide.

B) protect the body against infectious agents.

C) aid in the process of blood clotting.

D) carry nutrients from the intestine to the body’s cells.

E) absorb and neutralize the acids generated by active tissues.

14) ________ are the most abundant cell population of the formed elements of blood.

A) Erythrocytes

B) Platelets

C) Neutrophils

D) Lymphocytes

E) Monocytes

15) The percentage of whole blood volume occupied by cellular elements is termed (the) ________.

A) normovolemic

B) reticulocyte count

C) hematocrit

D) hemoglobin concentration

E) differential count

16) Excess transferrins are removed in the ________, where the iron extracted from heme molecules is stored in special protein-iron complexes.

A) liver and thymus

B) liver and spleen

C) thymus and bone marrow

D) spleen and bone marrow

E) thymus and spleen

17) When large numbers of RBCs break down in the circulation, the urine can turn reddish or brown in a condition called ________.

A) thalassemia

B) hemoglobinuria

C) anemia

D) leucopenia

E) septicemia

18) Red blood cell production is stimulated directly by

A) intrinsic factor.

B) thyroxine.

C) EPO.

D) vitamin B12.

E) GH.

19) During their formation, RBCs

A) flatten.

B) multiply their mitochondria.

C) eject their nucleus and most of their organelles.

D) are saturated with oxygen.

E) recycle hemoglobin.

20) ________ is a condition in which the oxygen-carrying capacity of RBCs is reduced.

A) Erythropoiesis

B) Lymphopoiesis

C) Anemia

D) Leukopenia

E) Leukemia