As you study the skeletal system, you’ll learn more about the

structure and functions of bone tissue, cartilage, and some

other connective tissues (4.2) that are major components of

the system.

Key ConCepts

LinKs to earLier ConCepts

The Structure and Functions

of Bones

Bones are built of bone tissue. They

store minerals, protect and support

soft organs, and function in body

movement. Some bones contain

marrow where blood cells develop.

S e c t i o n 5 .1

Top: Ed Reschke/Peter Arnold; Middle: both © Cengage Learning; Bottom:

Prof. P. Motta, Dept. of Anatomy, Univ. of La Sapienza, Rome/SPL/

Science Source

The Skeleton

The skeleton’s key function is to

serve as the body’s internal frame‑

work. Its 206 bones are organized

into two parts, the axial skeleton

and the appendicular skeleton.

Sections 5.2–5.4

Joints

At joints, bones touch or are in

close contact with one another.

Some of these connections permit

adjoining bones to move in ways

that in turn move body parts, such

as the limbs. Section 5.5

Susanna’s knees sometimes made her feel

more like 80 than 22. After 3 years of playing high school soccer,

in college she was downing multiple doses of an NSAID —a

nonsteroidal anti-inflammatory drug—just to make it through her

day. The problem? Soccer injuries had caused osteoarthritis in her

knee joints. Now they were stiff because the cartilage lining had

broken down and bone spurs had formed there.

The skeletal system in health and disease is our topic in this

chapter. Its parts—bones and joints that connect them—help

provide a sturdy framework for the body’s soft flesh. Bones also

partner with muscles to bring about the movements we take for

granted as we go about daily life.

87

6 The Muscular System

5

homeostasis preview

The skeleton and bones have many roles in homeostasis. In

addition to providing physical support, attachment points for

skeletal muscles, and protection for soft body parts, the skeleton

helps maintain proper calcium balance in the blood. Stem cells

in bone marrow are the source of our billions of blood cells.

Disorders of the Skeleton

Disorders that affect our bones

usually prevent them from function‑

ing normally. In addition to breaks

and arthritis, the skeleton may be

impaired by cancer, infections, and

other conditions. Section 5.6

connecTionS:

The Skeletal System in

Homeostasis Section 5.7

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