214 Laboratory Manual for Human Holy Accessory Organs Although not considered part of the digestive tract. the pancreas,

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214 Laboratory Manual For Human Holy Accessory Organs Although Not Considered Part Of The Digestive Tract The Pancreas 1 (69.34 KiB) Viewed 12 times

214 Laboratory Manual for Human Holy Accessory Organs Although not considered part of the digestive tract. the pancreas, salivary glands, liver, and gall- bladder play critical roles in the digestive process (Figure 17.2). The pancreas and salivary glands produce enzymes and other materials needed by the digestive system. As mentioned previously. the pancreas helps to neutralize the acid from the stomach by secreting bicarbonate ions, and it pro duces enzymes that help digest many kinds of food molecules. The salivary glands produce mucus and amylase, an enzyme that helps to break down starches into sugars. The liver produces bile, which is then stored and concentrated in the gallbladder. Although it is not an enzyme, bile plays an impor- tant role in fat digestion by breaking up or emulsify. ing large fat globules into much smaller ones. ACTIVITY 2 Identifying Human Digestive System Organs Materials for This Activity Human torso models Using Figures 17.2 and 17.4 as references, trace the pathway of food through the GI tract by identifying each of the following structures on the human torso models. • Esophagus • Stomach • Pancreas . Duodenum • Jejunum . lleum • Cecum • Ascending colon • Transverse colon Descending colon ACTIVITY 3 Observing the Major Digestive Organs in the Fetal Pig Materials for This Activity Fetal pig Dissection equipment Dissection tray Disposable gloves Because your fetal pig should already be open from previous lab exercises, you will now simply need to examine the inside of the pig in order to find these organs. Some of the organs will probably be familiar, considering they were pointed out previously as land- marks to help you find other structures. Please review the safety procedures for dissection provided by your instructor and those that appeared in Exercise 13. Figure 17.5 provides a reference for the dissection. 1. Obtain a fetal pig, place it faceup on a dissec- tion tray, and reattach the string as described in Exercise 13. 2. Locate the large dark liver, which covers much of the upper abdominal cavity. Lift up the lobes of the liver on the pig's right side, and locate the small, greenish, saclike gallbladder. What seer ion do the liver and gallbladder add to the digestive tract? 3. Lift up the lobes of the liver on the pig's left side, and locate the large, pale, saclike stomach. What are the most important functions of the stomach? 4. Follow the stomach toward the pig's right as it tapers down to join the duodenum. Then, fol- low the duodenum to where it hooks back to the pig's left. This is the start of the jejunum. Continue to follow the small intestine until it attaches to the large intestine. The latter half of the small intestine, which attaches to the large intestine, is the ileum. Because the jejunum and ileum are coiled together and difficult to differentiate, most sources refer to them collectively as the jejuno-ileum in the fetal pig. What is the main function of the small intestine? Why do you suppose that the small intestine is the single longest portion of the digestive tract? 5. At the junction of the large and small intestines, you should see a small, thumblike pouch called the cecum. The thicker intestine above the cecum is the colon, which is typically coiled together in the pig. For this reason, it is usually referred to as the spiral colon in the fetal pig. The colon straightens out to run along the back of the pelvic cavity and form the rectum.