HUMAN BIOLOGY

In this chapter your knowledge of concentration

gradients and diffusion (3.10) will help you understand the

mechanisms that move oxygen into and carbon dioxide out

of the body.

You will see how the respiratory system works together

with the cardiovascular system (7.1) to supply oxygen and

remove carbon dioxide.

You will also learn how hemoglobin and red blood cells

function in gas exchange (8.2).

Links to EarLiEr ConCEpts

Top three: © Cengage Learning; Bottom: © Brian Chase/Shutterstock.com

Tobacco smoke is a major risk factor for lung

cancer and also is linked with cancers of the tongue, throat,

and other tissues and organs. For example, females who start

smoking in their teens are about 70 percent more likely to develop

breast cancer than those who don’t smoke. Tobacco smoke

doubles the risk of heart disease because it elevates blood

pressure and blood levels of LDL (“bad”) cholesterol and lowers

levels of “good” cholesterol (HDL).

Anything we inhale that enters the bloodstream gets there by

way of the respiratory system, our focus in this chapter. Its parts

collectively have one basic job—to bring in oxygen, which cells

need for their metabolism, and to dispose of carbon dioxide,

which is the cells’ waste product.

10 The Respiratory System

© Tim Large/Shutterstock.com

177

homeostasis preview

Cells require oxygen for making ATP in mitochondria and also

must get rid of potentially toxic carbon dioxide produced by the

reactions. The respiratory system exchanges these gases with

the bloodstream.

kEy ConCEpts

The Respiratory System

Respiration provides the body with

the oxygen for aerobic respiration in

cells. It also removes waste carbon

dioxide. These gases enter and leave

the body by way of the respiratory

system. Sections 10.1–10.4

Gas Exchange

Oxygen and carbon dioxide are

exchanged across the thin walls

of microscopic sacs in the lungs

called alveoli. Circulating blood car-

ries gases to and from the lungs.

Section 10.5

Breathing Controls

The nervous system controls the

rate, depth, and rhythmic pattern of

breathing. Other controls match air

flow to blood flow. Section 10.6

Disorders of the Respiratory

System Sections 10.7–10.8

ConnECTionS:

The Respiratory System in

Homeostasis Section 10.9

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