Start date: 4/5/12

End date: 4/6/12

Project members: Naheen, Kyle, Mesha, Amna, Sandhya

Teacher’s name: Mr. Green

Background Information:

The excretory system regulates the chemical composition of body fluids by removing metabolic wastes and maintaining the proper amount of water, salts, and nutrients. Nitrogen wastes are a by product of protein metabolism. The urinary system is made up of the kidneys, ureters, bladder, and urethra. The nephron is the kidney’s functional unit. Water is filtered from the blood and collected as urine in the kidney. Urine leaves the kidney by ureters and collects in the bladder. The bladder can store urine until it leaves through the urethra. The nephron consists of a bowman’s capsule, the glomerulus, and a long renal tube. Blood flows into the kidney through the renal artery, which causes water and solutes to filter through the capsule. After the glomerular is done with the filtration, water and needed molecules are sent back into the blood and ions and wastes are sent into a distal tubule.

In this investigation, we will discover how the excretory system can be observed in fetal pigs.

Purpose: How can we observe the excretory system of the human body in fetal pigs?

Hypothesis: If we believe that fetal pigs are mammals with similar body forms as humans, then we should observe thr organs of the excretory system in a fetal pig and how they function.

Materials:

•Fetal pig

•Dissecting tools (scalpel, scissors, probe)

•Disposable gloves

•Camera

Procedure:

1.) Place the pig on its back in the dissecting pan. Tie a piece of string around the "wrist" of one of the front legs. Run the string under the width of the dissecting pan and tie it around the wrist of the other front leg. Pull the string fairly tight so that the legs are spread apart. Secure the hind legs in the same way.

2.) Being making incisions based on the image provided in your lab sheet. Pull apart the flaps of the body between the front and hind legs. Carefully pull up the flap with the umbilical cord a slight way. Cut off the umbilical vein.

3.) Rinse out the abdominal cavity of your specimen. Carefully push its organs aside until you see two bean shaped organs (kidneys). 4.) After identifying the kidneys, trace the ureter from the kidney to bladder. Identify the urethra, which carries urine outside of the body.

The large intestine breaks down wastes, which is later excreted.

(Fetal pigs send this waste to their mothers through the umbilical cord)

Analysis:

During this lab, I was able to observe the excretory system of a fetal pig. After wastes are filtered from blood in each kidney, urine leaves the kidneys through ureters. From this location, the urine is sent to the bladder. Here, it is stored and eventually leaves through the urethra. This fetal pig has not made use of its kidneys, ureter, urinary bladder, or urethra. This is because since the animal was never born, it used its mother’s umbilical cord in order to deposit its wastes. When you cut open a kidney, the lines that you see are the many blood vessels that filter out blood during filtration. The nephron are located in the medulla and cortex of the kidney, and appear like a group of bundled capillaries.

The large intestine, or the colon, is the last part of the excretory system observed. It is the organ that removes solid waste from the body. Its function is not only to remove solid waste but to collect water from the waste that can be reused. It is part of the alimentary canal. The waste is stored in the rectum until it is released through the anus.

Conclusion:

In conclusion, my hypothesis was correct. I was able to accurately observe the human excretory system in a fetal pig.

Fetal pigs are often used in classroom dissections. These mammals have similar hair, organ systems, metabolic levels, and body forms as humans. Their soft tissue and underdeveloped bones (cartilage) make them easier to dissect than other organisms. The fetal pig does not use their excretory system. All of their wastes are transferred by the umbilical cord to the mother, who excretes the wastes.

From this lab, I was able to learn that dissection is a work of art. It is important to make the correct incisions and restrain from damaging important organs and tissue. This lab has helped prepare me for future dissections.