Names ___________________________________ Date _____ Hour



Names ___________________________________ Date _____ Hour ______

Rat Dissection Abdomen

While opening the abdomen you must take great care. An improper cut here will damage the fragile organs found in this cavity. Very carefully cut #1, #2 and #3 as shown in the diagram below. Many structures for a variety of systems are found in this cavity.

The following is a list of the parts you need to find and identify:

1. The liver is the largest organ of the rat’s body (or your body). It is the large, multi-lobed reddish-brown organ filling the ventral and anterior portion of the abdominal cavity. Describe one function of the liver:

2. A saclike structure called the gall bladder is attached to the underside of your liver. It is usually green and partly embedded in the liver; however rats do not have one.

3. Directly posterior from the liver on the rat’s left side is a large pouch. This is the stomach. At the beginning and end of this pouch are two ring-like muscles called, ___________. Find one of theses muscles and show your teacher.

4. The tube entering the anterior portion of the stomach is the esophagus. It continues to ascend anterior to the mouth.

5. The small intestine is divided into three portions. Beginning at the stomach these are referred to as the duodenum, jejunum, and the ileum. The fragile tissue that connects the small intestines together is called the mesentery. The mesentery is full of arteries that are helping the small intestine with one of its primary functions. What function do these arteries serve?

6. The coiled mass of thick tubing is called the large intestine. You may cut open the lower portion of the large intestine (the descending colon) to find the substance contained within this tube.

7. Attached to the right side of the stomach is a long, sickle shaped reddish organ. The spleen is profusely vascular. Use your notes or memories to list two jobs of the spleen here:

8. The feathery beige organ that lies directly below the spleen and extends along the underside of the stomach is the pancreas. Name and describe one disorder associated with the pancreas here:

9. Above the rat’s liver note the thin drum-like muscles of the diaphragm. The boundary between the abdomen and the thorax is the diaphragm. Briefly describe how the diaphragm can accomplish its job of filling and emptying the lungs here:

10. At the junction of the small and large intestines is the caecum joining ileum to the ascending colon, note the attached appendix. One job of the appendix is to produce white blood cells. Why would rats need more white blood cells than humans?

11. Push the intestines as far to your left as possible. The tube leading from the large intestine out of the abdominal cavity is the rectum.

12. A sphincter controls the opening of the rectum to the outside of the body. This opening is the anus. Why is this sphincter important?

Color each part the correct color in the diagram:

← Liver (blue)

← Duodenum (red)

← Diaphragm (orange)

← Stomach (yellow)

← Pancreas (green)

← Jejunum (brown)

← Ileum (black)

← Large intestine (purple)

← Caecum (light blue)

← Spleen (light green)

← Sphincters (light red)

← Rectum (light brown)

← Anus (light black)

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