This chapter expands on our discussion of the cardiovas-

cular system in Chapter 7. Red blood cells contain the

oxygen-carrying protein hemoglobin (2.12), and all blood

cells develop in red bone marrow (5.2).

Our discussion here of blood typing shows a key function

of the recognition proteins in cell plasma membranes (3.4).

Section 8.7 on blood clotting provides good examples of

how enzymes catalyze chemical reactions that are vital to

life (2.8).

KeY ConCePts

linKs to eARlieR ConCePts

Components and Functions

of Blood

Blood consists of plasma, red blood

cells, white blood cells, and plate-

lets. Red blood cells carry O 2 and

CO 2 , white blood cells function in

defense, and platelets help clot

blood. Circulating blood helps main-

tain proper pH and body temperature.

Sections 8.1–8.3

From top: National Cancer Institute/Science Source; Lester V. Bergman/

Encyclopedia/Corbis; Eye of Science/Science Source; Science Source

Blood Types

Surface markers on red blood cells

establish each person’s blood type.

Sections 8.4–8.5

Blood Clotting

Mechanisms that clot blood help

prevent blood loss. Section 8.7

When Carlos needed a leaky heart valve repaired,

the surgeon urged that he have some of his blood drawn and

stored in case a transfusion was needed. A major reason for the

precaution: Carlos had type O^2 blood. A complex gene-based

system determines the characteristic we call blood type. Because

relatively few people inherit type O^2 , it often is in short supply in

blood banks. And if Carlos were to need blood during the surgery,

only donor blood that was a near-perfect genetic match to his

would be usable. Otherwise, his immune system would launch a

potentially fatal attack on the replacement cells.

Blood’s “type” is only one of the key characteristics of blood.

As you’ll learn in this chapter, an amazingly versatile substance

courses through your arteries and veins.

BlooD

8

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Homeostasis Preview

Blood transports oxygen, nutrients, and other materials. It also

carries ions important for maintaining proper pH in extracellular

fluid. Blood-borne proteins have many physiological roles.

Some function in blood clotting, which prevents minor injuries

from leading to dangerous blood loss.

Blood Disorders Section 8.9

Samuel Ashfield/Science Source

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