This chapter builds on your knowledge of hormones, includ-

ing the sex hormones estrogen and testosterone (15.1, 15.2).

You will see how negative feedback loops (4.10) regulate

the production of sperm in males and the menstrual cycle

in females.

You will also learn more about chromosomes, the structures

that carry genes (3.6).

Key ConCepts

LinKs to earLier ConCepts

305

The Female Reproductive

System

Ovaries are a female’s primary

reproductive organs. Hormones

control their functions, such as the

development of oocytes (eggs).

Sections 16.1–16.2

Infertility affects one in seven couples.

For one reason or another, some couples are unable to conceive

after “trying” for 1 year. Depending on the source of the problem,

treatment may include injections of fertility drugs that promote

release of the woman’s eggs. These eggs are used in an assisted

reproductive technology, such as laboratory fertilization, as a first

step toward pregnancy.

The biological role of the reproductive system is to continue

the human species. In this chapter our main focus is the normal

functioning of the female and male reproductive systems. We

also consider related topics such as infertility and sexually

transmitted disease.

Top two: © Cengage Learning; Second from bottom: David M. Phillips/

Science Source; Bottom: David M. Phillips/Science Source

reproduCtive systeMs

16

The Male Reproductive

System

A male’s reproductive system

consists of testes and accessory

ducts and glands. As in females,

hormones control its functions,

which include making sperm.

Sections 16.3 –16.4

Intercourse and Fertility

Sexual intercourse between a male

and female is the usual first step

toward pregnancy. Various methods

exist for limiting or enhancing fertil-

ity. Sections 16.5 –16.8

Sexually Transmitted

Diseases and Cancers

of the Reproductive System

Sexual contact can transmit

bacteria, viruses, and other disease-

causing pathogens. Sections

16.9 –16.12

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