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21
520

Chapter 21 Growth and Development

Growth and Development
Outline

PRENATAL PERIOD, 522

Fertilization to Implantation, 522
Periods of Development, 527
Formation of the Primary Germ
Layers, 527
Histogenesis and Organogenesis, 527
Birth Defects, 530
BIRTH, OR PARTURITION, 530
Stages of Labor, 530
POSTNATAL PERIOD, 530
Infancy, 533
Childhood, 534
Adolescence and Adulthood, 534
Older Adulthood, 535
EFFECTS OF AGING, 536
Skeletal System, 536
Integumentary System (Skin), 536
Urinary System, 536
Respiratory System, 538
Cardiovascular System, 538
Special Senses, 538

520

Objectives

AFTER YOU HAVE COMPLETED THIS
CHAPTER, YOU SHOULD BE ABLE TO:
1. Discuss the concept of development as a
biological process characterized by continuous modification and change. 2. Discuss the major developmental changes
characteristic of the prenatal stage of life from
fertilization to birth.
3. Discuss the three stages of labor that characterize a normal vaginal birth. 4. Identify the three primary germ layers and
several derivatives in the adult body that develop from each layer. 5. List and discuss the major developmental
changes characteristic of the four postnatal
periods of life.
6. Discuss the effects of aging on the major
body organ systems.

S TUDY TIPS

M

any of your fondest and most vivid
memories are probably associated with
your birthdays. The day of birth is an
important milestone of life. Most people continue
to remember their birthday in some special way
each year; birthdays serve as pleasant and convenient reference points to mark periods of transition or change in our lives. The actual day of birth marks the end of one phase of life called the
prenatal period and the beginning of a second
called the postnatal period. The prenatal period
begins at conception and ends at birth; the postnatal period begins at birth and continues until death. Although important periods in our lives such as
childhood and adolescence are often remembered
as a series of individual and isolated events, they
are in reality part of an ongoing and continuous
process. In reviewing the many changes that occur
during the cycle of life from conception to death, it
is often convenient to isolate certain periods such
as infancy or adulthood for study. It is important
to remember, however, that life is not a series of
stop-and-start events or individual and isolated
periods of time. Instead, it is a biological process
that is characterized by continuous modification
and change.
This chapter discusses some of the events and
changes that occur in the development of the individual from conception to death. Study of development during the prenatal period is followed by a discussion of the birth process and a review of

To make the study of human growth and
development more efficient, we suggest
these tips:
1. Review the concepts of human reproduction from the previous chapter. 2. The term germ in primary germ layer
refers to “germinate.” All the structures of the body come from one of these layers. They are named based
on their location in the developing embryo. Endoderm means inner skin, mesoderm means middle skin, and
ectoderm means outer skin.
3. Genesis means to create. Histogenesis means to create tissues, and organogenesis means to create organs. 4. The early developmental stages can
be put on flash cards. You might also
want to include on the flash card
where in the developmental sequence
the particular stage is, in other words,
what it developed from. Remember to
include the functions of the amnion,
chorion, and placenta. In your study
group, go over the flash cards of the
stages of development, making sure
you know the proper sequence.
5. Use flash cards to match the primary
germ layers and the structures that
come from each of them.
Continued on page 545
521

522

Chapter 21 Growth and Development

changes that occur during infancy and adulthood.
Finally,...
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