458 Chapter 9 Human Body Orientation
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Recall Activity
1. The two layers of epithelium in the small intestine are the __________________________ and the
__________________________.
2. The layer of connective tissue in the small intestine is called the __________________________.
3. Which tissue layer lines the inside of the alimentary canal? _________________________________________
Concept 5: Body System Level
Organs that work together to perform a group of functions make up a
body system
(also known as an organ system). For example, the organs of the
alimentary canal, as well as some other organs (such as the salivary glands,
liver, pancreas, and gallbladder), make up the digestive system. Together, all of
these organs perform the functions of moving food, digesting food (chewing
food into small pieces and breaking pieces into macromolecules), and absorb-
ing macromolecules for use throughout the body.
The human body has 11 systems (Figure 9.18):
• integumentary system
• skeletal system
• muscular system
• nervous system
• endocrine system
• respiratory system
• cardiovascular system
• lymphatic system
• digestive system
• urinary system
• reproductive systems (male and female)
You will learn about the basic organs and functions of these body systems
in Chapter 10.
body system a group of
organs that work together to
perform several functions;
also called an organ system
Lamina propria
Serosa
Mucosa
Muscle layers
© Body Scientific International
Figure 9.17 The small intestine has four layers of tissue.