biology
Frank55
collage.doc|
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Experiment 1: Microscopic Anatomy of the Digestive System
Visualizing the microscopic anatomy of the digestive system will aid in your understanding of its function.
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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. |
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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. |
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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. |
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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. |
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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. |
Post-Lab Questions
1. Label the items in the following slide pictures.
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.
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
