Functions and Properties of Blood

Objectives

When you have completed this section, you should be able to

• list several functions of blood;
• list the blood's fluid and cellular components; and
• explain the causes and significance of the blood's viscosity and osmolarity.

Key Point Review

1. About how much blood is in your body? Give answers in both units of weight and volume.

2. What are the principal components of the blood?

3. What percentage of the blood is plasma?

4. Why is blood viscosity important? What are the main factors that contribute to blood viscosity?

5. Why is osmolarity important? What are the main factors that contribute to blood osmolarity?

Plasma

Objectives

When you have completed this section, you should be able to

• distinguish between plasma and serum;
• list the proteins of blood plasma and state their functions;
• name the nonprotein nitrogenous compounds of blood plasma and explain their significance; and
• list the major nutrients, gases, and electrolytes found in plasma.

Think About It

What would be the rationale for giving intravenous albumin to a patient who has experienced fluid loss and low blood volume?

Key Point Review

6. List the three major classes of plasma proteins. Which one is missing from blood serum?

7. What are the functions of blood albumin?

8. List some organic and inorganic components of plasma other than protein.

Blood Cell Formation

Objectives

When you have completed this section, you should be able to

• explain where the formed elements of blood are produced in fetuses, children, and adults;
• describe the early stages of blood cell production and state the factors that influence its rate; and
• explain how uncommitted stem cells become committed to forming specific types of blood cells.

Key Point Review

9.   List the fetal tissues and organs that produce blood.

10. How do the sites of hemopoiesis differ between children and adults?

11. Distinguish between lymphoid and myeloid hemopoiesis.

12. How is a hemocytoblast different from a committed hemopoietic cell?

Erythrocytes

Objectives

When you have completed this section, you should be able to

• describe the structure of erythrocytes;
• describe the structure and function of hemoglobin;
• describe the ways in which the erythrocyte and hemoglobin content of the blood are quantified and explain why these values differ between men and women;
• describe the life cycle of erythrocytes; and
• describe the types of anemia and polycythemia and their causes and effects.

Think About It

Hemoglobin is sometimes considered an enzyme. Based on what you know of hemoglobin and what you have learned about enzymes in chapter 3, do you agree? Why or why not?

Key Point Review

13. Describe the shape, size, and contents of an erythrocyte and explain how it acquires its unusual shape.

14. What is the function of hemoglobin? What are its protein and nonprotein moieties called?

15. What happens to each of these moieties when old erythrocytes break up?

16. What is the body's primary mechanism for correcting hypoxemia? How does this illustrate homeostasis?

17. What are the three primary causes or categories of anemia? What are its three primary consequences?

Blood Types

Objectives

When you have completed this section, you should be able to

• explain what determines a person's ABO blood type and how this relates to transfusion compatibility;
• explain what determines a person's Rh blood type and how this relates to transfusions and mother-fetus compatibility; and
• list some blood groups other than ABO and Rh and explain how they may be useful.

Think About It

What percentage of Japanese Americans would be expected to have type B^- blood?

Think About It

A baby with HDN typically has jaundice and an enlarged spleen. Explain these symptoms.

Key Point Review

18. What are agglutinins and agglutinogens? How do they interact to cause a transfusion reaction?

19. What agglutinins and agglutinogens are present in people with each of the four ABO blood types?

20. Describe the cause, prevention, and treatment of HDN.

21. Why might someone be interested in determining a person's blood type other than ABO/Rh?

Leukocytes

Objectives

When you have completed this section, you should be able to

• state the general function of leukocytes;
• name and describe the five types of leukocytes; and
• name the different types of abnormal leukocyte counts and discuss their causes and effects.

Key Point Review

22. What is the overall function of leukocytes?

23. What can cause abnormally high or low leukocyte counts?

24. Define leukemia. Distinguish between myelocytic and lymphocytic leukemia.

Hemostasis

Objectives

When you have completed this section, you should be able to

• describe the mechanisms that stop bleeding in the event of injury;
• list the functions of platelets;
• describe the two pathways of blood clotting;
• explain what happens to blood clots when they are no longer needed;
• explain what keeps blood from clotting in the absence of injury; and
• describe some disorders of blood clotting.

Think About It

Why is it important for people with hemophilia not to use aspirin? (Hint: See chapter 17.)

Key Point Review

25. What are the three basic mechanisms of hemostasis?

26. How do the extrinsic and intrinsic mechanisms of coagulation differ? What do they have in common?

27. In what respect does blood clotting represent a negative feedback loop? What part of it is a positive feedback loop?

28. Describe some of the mechanisms that prevent clotting in undamaged vessels.

29. Describe a common source and effect of pulmonary embolism.

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