Download Experiment 1: Microscopic Anatomy of the Digestive System

Experiment 1: Microscopic Anatomy of the Digestive System
Visualizing the microscopic anatomy of the digestive system will aid in your
understanding of its function.
Materials
Esophagus Digital Slide Image
Small Intestine Digital Slide Image
Stomach Digital Slide Image
Procedure
1. Examine the esophagus digital slide images.
2. Draw your observations in the space below. Be sure to note what structural
components of the esophagus are visible.
3. Examine the small intestine digital slide images.
4. Draw your observations in the space below. Be sure to note what structural
components of the small intestine are visible.
5. Examine the stomach digital slide images.
6. Draw your observations in the space below. Be sure to note what structural
components of the stomach are visible.
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Esophagus 40X. Non-keratinized, stratified, squamous epithelium (indicated as
“epithelia” in the image below) lines the lumen of the esophagus. The lamina propria,
composed of connective tissue, resides just below the epithelia. These two layers
comprise the mucosa.
Esophagus: 100X
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Esophagus 1000X. Esophageal glands are present within the lamina propria.
These racemose glands (glands formed through a cellular aggregation)
are relatively small in size and function to lubricate food as it travels down the
esophagus.
Small Intestine 100X. The mucosa of the small intestine is composed of simple,
columnar epithelium (enterocytes) which includes absorptive cells, goblet cells, and
enteroendocrine cells.
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Small Intestine 1000X. Mucosal glands, also called crypts of Lieberkühn, include paneth
cells and stem cells. Therefore, mitotic activity is often visible in these structures.
Stomach 40X. The stomach is characterized by a thick mucosal layer. This layer
protects the stomach from self-digestion. It contains some lamina propria, but is
primarily composed of secretory cells such as parietal cells and chief cells which
lubricate the region.
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Stomach 100X. Densely packed gastric pits line the epithelial surface of the stomach
mucosa. These pits extend inward and open in the mucosa, creating gastric glands
(also known as fundic glands). These glands are also densely packed, and are
composed of cells which vary in size, shape, and appearance.
Stomach 1000X. Surface mucous cells line the exterior of the gastric pit and secrete
mucous and bicarbonate ions. Neck mucous cells are found near the parietal cells, and
secrete additional mucous. Parietal cells are found in the gastric gland, and appear
pink. Chief cells are typically found near the base of a gastric gland, and appear purple.
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Post-Lab Questions
1. Label the items in the following slide pictures.
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2. What is unique about the small intestine mucosa?
Swallowing
Deglutition, the process of swallowing, is largely the result of skeletal muscle activity.
There are two phases involved with this action, beginning with a voluntary decision that
is initiated by the tongue. The second phase is involuntary, and utilizes peristaltic
movements to move the substance through the pharynx and esophagus until it reaches
the stomach.
Procedure
1. Swallow a mouthful of water, and observe the movement of your tongue during
the process.
2. Swallow another mouthful of water and note the movements in the throat. Note
your observations at the end of this procedure.
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3. Position the earpieces of the stethoscope appropriately, and place the
chestpiece one inch below the xiphoid process (at the lower end of the
breastbone).
4. Take a few sips of water, and listen for two “splashes”; one when water enters
the esophagus, and the second when water enters the stomach.
Observations
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