Body Structure Is Closely Linked to
Function at All Levels of Organization
LEARNING OBJECTIVES
1.
Compare
anatomy and physiology.
2.
Outline
the levels of organization of the human
body.
s a city has structures and each structure has
a function, so does the human body. We refer
to the sciences of the structure and function
of the human body as anatomy and physiol-
ogy.
A n ato m y
(a-NAT-o-me;
ana-
= up;
-tomy
= process
of cutting) is the science of
structure
and the relationships
among structures.
P h ysio lo gy
(fiz'-e-OL-o-je;
physio-
=
nature,
-logy
= study of) is the science of body
functions
3.
Describe
the function of each major organ sys-
tem in the body.
that is, how the body parts work. Because function can
never be separated completely from structure, the hu-
man body is easiest to understand by studying anatomy
and physiology together. We will look at how each struc-
ture of the body is designed to carry out a particular func-
tion and how the structure of a part often determines
the functions it can perform. For example, the bones of
the skull are rigidly joined to protect the brain, whereas
InSight
Le v e ls o f stru ctu ral o rg a n iza tio n o f th e h u m an b o d y
Figure 1.1
Level
1.
Ch em ical
The chemical level contains atoms, the
smallest units of matter. Common atoms
in living things include carbon (C),
hydrogen (H), oxygen (O), nitrogen (N),
and phosphorus (P). Atoms combine to
form molecules such as deoxyribonucleic
acid (DNA), the cell’s genetic material.
9
° 9
n
Atoms (C, H, O, N, P)
7
^
Level
2.
Cellu lar
Cells are the basic structural and
functional unit of any organism.
Your body has about 1
trillion cells.
Although each cell must carry out
the basic functions of life, most
cells in your body are specialized
to do one particular function. For
example, the smooth muscle cells
of the stomach can be stretched to
accommodate a large meal.
Smooth muscle cell
Molecule (DNA)
^WILEY©
PLUS
NATIONAL
GEOGRAPHIC
Video
J
Level 3. T issu e
Tissues are composed of groups of cells
and their surroundings (intercellular
substances) that work together to
perform a particular function. There are
four types of tissues: epithelial, muscle,
connective, and nervous.
Smooth muscle tissue
2 CHAPTER 1
Organization of the Human Body
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