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 reddishbrown organ filling the ventral and anterior portion
of the abdominal cavity. Describe one function of
the liver:
2
1
3
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)