Endocrine Dissection and Identification Lab

Objectives:

1. Identify major organs in the thoracic and abdominal cavities.

2. To identify and name the major endocrine glands/organs on a dissected cat.

 

Materials:

Cat, tray, paper towels, pins, 3X5 card sections for flags.

 

Thoracic cavity organs:

Heart: in the mediastinum enclosed by the pericardium

 

Trachea: The windpipe runs down the midline of the throat and then divides just anterior to the lungs to form the bronchi which plunge in to the lungs on either side.

 

Thyroid: Its dark lobes straddle the trachea. This endocrine organís hormones are the main hormones regulating the bodyís metabolic rate.

 

Lungs: Paired organs flanking the heart.

 

Thymus: Glandular structure superior to and partly covering the heart. The thymus is intimately involved ( via its hormones ) in programming the immune system. If you have a young cat, the thymus will be quite large. In old cats, most of this organ will be replaced by fat.

 

Abdominal Cavity Organs:

Liver: large multilobed organ lying under the umbrella of the diaphragm

††††††††††††††† Lift the drapelike, fat infiltrated greater omentum covering the abdominal organs to expose the following organs

 

Stomach: Dorsally located sac to the left side of the liver.

 

Spleen: Flattened brown organ curving around the lateral aspect of the stomach.

 

Small Intestine: tubelike organ continuing posteriorly from the stomach .

 

Pancreas: diffuse gland lying deep to and between the small intestine and stomach. Lift the first section of the small intestine with you r forceps you should see the pancreas situated in the delicate mesentery behind the stomach. This gland is extremely important in the regulation of blood sugar levels.

 

Large Intestine: Taking a U shaped course around the small intestine to terminate in the rectum.

†††††††††††††† Push the intestines tone side with a probe to reveal the deeper organs of the abdominal cavity.

 

Kidneys: Bean shaped organs located toward the dorsal body wall surface and behind the peritoneum

 

Adrenal glands: Seen above and medial to each kidney, these small glands produce corticosteroids important in preventing stress and abnormalities of water and electrolyte balance in the body.

 

Gonads (ovaries and testes) Sex organs producing sex hormones. The location of the gonads is illustrated in Fig 33.

 

Dissection Questions:

1.How do the locations of the endocrine glands/organs in the cat compare with the human?

2. Name the two endocrine organs located in the throat region.

3. Name the three endocrine organs in the abdominal cavity.

4. Given the assumption ( not necessarily true) the human beings have more stress than a cat, which endocrine organs would you expect to be relatively larger in humans?

5. Cats are smaller animals than humans. Which would you expect to have a more active thyroid gland. Cats or humans? (relatively speaking) Why?