Haspi Medical Anatomy Physiology Lab Form – Fill Out and Use This PDF

The Digestive System

Digestion is an important process that involves breaking down food and drink into small molecules that can be transported and used by the cells of the body. The digestive system consists of a one-way track, called the gastrointestinal (GI) tract, that food travels through. At various points of the GI tract, digestion, absorption, and elimination occur. Each portion has been structured to perform a specific function.

The GI tract includes the mouth, esophagus, stomach, small intestine, large intestine or colon, rectum, and anus. These organs contain a layer of tissue called the mucosa that is responsible for creating digestive juices, such as enzymes, that are capable of breaking down food. In addition to the mucosa layer there is also a tissue layer of smooth muscle that assists in moving food through the GI tract called the muscularis mucosae. The rhythmic contraction and relaxation of this smooth muscle layer is called peristalsis.

In addition to the GI tract, there are also two solid organs that

assist with digestion by creating and releasing substances into http://denverdigestive.com/art/DigestiveSystem.jpg the GI tract. The pancreas produces several digestive enzymes, while the liver is responsible for creating bile needed to break down fat. An additional accessory organ is the gallbladder that stores the bile produced by the liver.

The Process of Digestion

1Once food enters the mouth, salivary glands produce saliva that contains amylase. Amylase begins the digestion of starch and carbohydrates.

2From the mouth, food is pushed down the esophagus by swallowing. The food then passes through the

cardiac sphincter into the stomach. The cardiac sphincter prevents the contents of the stomach from moving back up the esophagus.

3Within the stomach, digestive glands within the lining of the stomach produce acid and pepsin to break

down proteins. A thick layer of mucus is also released to protect the stomach from the acid.

4The stomach is a muscular pouch that contracts and releases to “mix up” the food and digestive juices of the stomach much like a washing machine. Once the food is properly mixed, the stomach pushes the

contents through the pyloric sphincter into the first part of the small intestine, called the duodenum.

5The liver, pancreas, and gallbladder are attached to the duodenum through ducts and release additional digestive juices into the small intestine. These include bile to emulsify fats, amylase to further break down carbohydrates, lipase to break down lipids, and trypsin to further break down proteins.

6As the contents travel through the small intestine, they are absorbed through small projections on the surface of the intestines called villi. Each villi is connected to a capillary so, as molecules diffuse through the villi, they are transferred directly into the blood stream to be taken to the cells of the body.

7Eventually, any contents that are left and have not been absorbed by the small intestine are pushed through the ileocecal valve into the colon.

8As the contents move through the colon, water is removed and the leftover contents become feces that are expelled through the rectum and anus during a bowel movement.

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Digestive Disorders

There are many diseases and disorders associated with the digestive system. Some of the most important aspects of digestive disorders are the prevalence, healthcare costs, and mortality. Digestive disorders cost the U.S. approximately $141.8 billion dollars in 2004. The following chart summarizes the impact of the most common digestive disorders in the United States in 2004.

Diagnostic Tests for Digestive Disorders There are many diagnostic tests for digestive disorders. Biopsy samples, gastric juice samples, or stool samples can be used to recognize whether there may be a digestive source for a patient’s symptoms. Following lab tests that may signify a digestive disorder, imaging of the GI tract can be used. The

most effective diagnostic procedures involve using an endoscope to view portions of the GI tract with a camera. When this process is done through the rectum to view the colon, it is called a colonoscopy. When this process is done through the mouth to

view the esophagus, stomach, and/or duodenum, it http://www.merckmanuals.com/media/home/figures/GI_d

Upper and lower GI series can also create radiographic images of the GI tract using a contrast dye, such as barium. The images can show blockages, strictures, or other issues that may exist with the passage of food through the intestines. Using these imaging techniques, healthcare specialists are able to view and identify inflammation, ulcers, growths, and bleeding.

NIH. 2008. Your Digestive System and How it Works. National Institutes of Health (NIH), National Digestive Diseases Information Clearinghouse (NDDIC), NIH Publication No. 08-2681, http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/

NIH. 2010. Digestive Diseases Statistics for the United States. No. 10-3873,

http://digestive.niddk.nih.gov/statistics/statistics.aspx#ack

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This is a station lab activity. There are 6 stations set up around the classroom. Each station will take approximately 10-15 minutes.

Station 1: The Digestive System

Digestive System Anatomy – Using the “Digestive System Anatomy” chart, identify the organs or parts of the organ labeled A-W in Table 1 below. If there are any that you cannot identify, use a textbook or online resource. A smaller version of this chart is included here for later review.

The Stomach – Using “The Stomach” chart, identify the parts of the organ A-K in Table 2 below. If there are any parts you cannot identify, use a textbook or online resource. A smaller version of this chart is included here for later review.

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The Large Intestine – Using “The Large Intestine” chart, identify the parts of the organ A-S in Table 3 below. If there are any parts you cannot identify, use a textbook or online resource. A smaller version of this chart is included here for later review.

Digestive System Function – Fill in the function of each digestive organ in Table 4. Use the “Digestive Organ Function” chart to check your answers. Make any changes if needed.

Table 4: Digestive System Function

Function

Mouth

Salivary Gland

Pharynx

Esophagus

Stomach

Pancreas

Liver

Gallbladder

Small Intestine

Large Intestine

Rectum

Anus

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Station 2: The GI Tract Adapted from “The Digestive System” by M. Poarch, 2002.

The entire length of the adult GI tract from mouth to anus is approximately 9-10 meters in length. Various portions of the GI tract vary in length depending on their function. The large majority of this length is located in the intestines. In this activity we will be measuring out the length of the GI tract in a scaled version to compare the lengths of each section.

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Station 3: Digestive System Histology

The cell and tissue structure of digestive organs is suited for the function they perform. Draw and label what you see in Image B for the following digestive organs below. Image A in each chart is for reference!

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Station 4: Gravity or Peristalsis? Adapted from “Fast Food” by M. Poarch, 2004. The time it takes food and drink to pass through the GI tract can vary from 24 hours to 3 days depending on the type and ingredients. For example, carbohydrates are digested very quickly and only remain in the stomach for an hour at most, while protein and fat can remain in the stomach for several hours for further digestion. In this activity you will investigate how long it takes water to move through the esophagus and whether gravity affects the speed at which it reaches the stomach.

Table 5. Time for Water to Reach the Cardiac Sphincter

Trial 1

Trial 2

Trial 3

Average

Laying Down Time in Seconds

Trial 1

Trial 2

Trial 3

Average

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Station 5: Digestive Disease

Using the digestive disease charts, complete the following table. List ONLY THREE Causes or Risk Factors, Symptoms, and Treatment Options for each disease.

Cholecystitis

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Station 6: Digestive Lab Tests

There are many different types of diagnostic tests that can be used to identify possible digestive disorders. One of the most common tests is the fecal occult blood test to search for trace amounts of blood in the stool. A healthy individual will normally have a small amount of blood loss into the stool daily, but a primary symptom of many digestive disorders is chronic bleeding in the GI tract. Blood in the stool may be indicative of ulcers, polyps, cancer, anal fissures, infection, hemorrhoids, diverticulitis, colitis, and esophageal bleeding just as a few examples.

Since chronic bleeding indicates a bigger issue, it is more useful to perform several fecal occult blood tests over a period of time rather than just accept the results from a single test. In this activity, you will be testing 2 samples collected from a patient who has been experiencing abdominal cramping over a period of several months. Sample A is the initial sample and Sample B was collected 3 days after Sample A.

Analysis Questions - on a separate sheet of paper complete the following

Station 1

1.What are the accessory organs of the digestive system that are not actually part of the GI tract?

2.What are the three parts of the small intestine?

3.What valve separates the esophagus and stomach? The stomach and the duodenum?

4.What valve separates the ileum from the colon?

5.What are the three parts of the large intestine or colon?

6.What are the functions of the liver and gallbladder?

7.What is the function of the pancreas?

Station 2

8.What is the longest part of the GI tract?

9.Why do you think the small intestine is so much longer than the large intestine?

10.Did the length of any portions of the GI tract surprise you? Why or why not?

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