Introduction to Anatomy – Lesson 2
TSWBAT list the levels of structural
organization.
Levels of Structural Organization
• Chemical (or molecular level)
• Cellular
• Tissue
• Organ
• Organ System
• Organism
Levels of Structural Organization
1. Chemical – Atoms (smallest stable units of matter)
combined to form molecules (complex shapes of two or
more atoms).
2. Cellular – Molecules interact to form organelles.
Organelles are components of cells (smallest living units
in the body). Example – cardiac muscle cells
3. Tissue – Groups of similar cells that have a common
function. (example – cardiac muscle tissue)
Levels of Structural Organization
4. Organ – A structure that is
composed of two or more tissue
types and performs a specific
function for the body (example –
heart: cardiac muscle tissue and
smooth muscle tissue).
5. Organ System – A group of
organs that cooperate to accomplish
a common purpose (example –
cardiovascular system; heart, blood,
blood vessels).
Levels of Structural Organization
6. Organism – Made up of the organ
systems. Highest level of structural
organization (example – human).
Levels of Structural Organization
Smooth muscle cell
Molecules
2 Cellular level
Cells are made up of molecules
Atoms
Smooth
muscle
tissue
3 Tissue level
Tissues consist of
similar types of
cells
1 Chemical level
Atoms combine to
form molecules
Heart
Cardiovascular
system
Epithelial
tissue
Smooth
muscle
tissue
Connective
tissue
4 Organ level
Organs are made up of
different types of tissues
Blood
vessels
Blood
vessel
(organ)
6 Organismal level
The human organism is
made up of many organ
systems
5 Organ system level
Organ systems consist of different organs
that work together closely
Figure 1.1
1. Two or more atoms join together to
form what organizational structures?
2. Which levels of structural organization are you
unable to see with your naked eye?
3.Which level of structural organization is composed
of two or more different types of tissues that work
together to perform a specific function?
4. How are organs and tissues different?