CHAPTER 19 Cardiovascular System: Blood

669

routinely done when a blood sample is taken, and additional testsare available.

ASSESS YOUR PROGRESS

45. What occurs in a type and crossmatch? 46. What tests are included in a CBC? Give the normal value,and name a disorder that would cause an abnormal testresult for each. 47. What are the normal values for a platelet count and aprothrombin time measurement? Name a disorder thatwould cause an abnormal result for each test. 48. What are some examples of blood chemistry tests?

Predict 9

When a patient complains of acute pain in the abdomen, the physiciansuspects appendicitis, which is often caused by a bacterial infection ofthe appendix. What blood test should be done to support thediagnosis?

Learn to Predict

Answer

From page 644

red blood cell production in the red bone marrow. Because ofFrankie’s iron deficiency, which caused hemoglobin synthesis toslow, the newly synthesized red blood cells were smaller than nor-mal, or microcytic. Remember, Frankie also complained of intenseabdominal pain. The evidence of hemoglobin in her feces sug-gested that Frankie is losing blood into her digestive tract, which,considering her abdominal pain, would be consistent with havingan ulcer. Frankie’s doctor would need to order additional teststo confirm the presence of ulcers before determining treatment.

Answers to the rest of this chapter’s Predict questions are inappendix G.

Frankie’s feeling of fatigue and her blood test results are consis-tent with anemia. A low red blood cell count with microcytic cells,low hemoglobin, and a low hematocrit are all indicators of irondeficiency anemia.The increased reticulocyte count indicated an increased rateof red blood cell production. But if red blood cell production wasincreased, why was Frankie’s red blood cell count still low? Welearned in this chapter that red blood cell production is regulatedby the hormone erythropoietin. Specifically, reduced red bloodcell numbers, as indicated by Frankie’s blood test, caused lessoxygen to be transported to her kidneys. Consequently, her kid-neys secreted more erythropoietin, which resulted in increased

19.1 Functions of Blood (p. 645)

1. Blood transports gases, nutrients, waste products, processed mol-ecules, and regulatory molecules.2. Blood is involved in the regulation of pH, osmosis, and body temperature.3. Blood protects against disease and initiates tissue repair.

Summary

Production of Formed Elements

1. In the embryo and fetus, the formed elements are produced in a numberof locations.2. After birth, red bone marrow becomes the source of the formed elements.3. All formed elements are derived from hemocytoblast, which gives riseto two intermediate stem cells: myeloid stem cells and lymphoid stemcells. Myeloid stem cells give rise to red blood cells, platelets, andmost of the white blood cells. Lymphoid stem cells give rise tolymphocytes.

19.2 Composition of Blood (p. 645)

Blood is a type of connective tissue that consists of plasma and formedelements.

19.3 Plasma (p. 645)

1. Plasma is mostly water (91%) and contains proteins, such as albumin(maintains osmotic pressure), globulins (function in transport andimmunity), fibrinogen (involved in clot formation), and hormonesand enzymes (involved in regulation).2. Plasma contains ions, nutrients, waste products, and gases.

Red Blood Cells

1. Red blood cells are biconcave discs containing hemoglobin and car-bonic anhydrase. ■ A hemoglobin molecule consists of four heme and four globinmolecules. The heme molecules transport oxygen, and the globinmolecules transport carbon dioxide and nitric oxide. Iron is requiredfor oxygen transport. ■ Carbonic anhydrase is involved with the transport of carbondioxide.

19.4 Formed Elements (p. 646)

The formed elements are red blood cells (erythrocytes), white blood cells(leukocytes), and platelets (cell fragments).