<p> Name: ______</p><p>FROG DISSECTION Examining the Organ Systems of an Amphibian</p><p>The organ and organ systems of a frog are similar to those of a human. By studying the internal organ systems of a frog you can gain an understanding of the organization and function of human systems as well.</p><p>In this dissection you will examine the digestive, circulatory, and respiratory, systems of a frog. As well, you will look at the organs that make up these systems and see how they work together to carry out the functions of their system. You will consider the interrelationships of these systems and how they work together. You will also be able to examine some of the organs in the nervous and reproductive systems. </p><p>Safety Precautions: * Care must be taken in using dissection instruments. In particular, instruments such as scalpels are extremely sharp. Whenever possible, cuts should be made away from your body or hands.</p><p>*Frogs are preserved in a chemical solution. Wear the protective equipment provided such as gloves and safety glasses when working with them.</p><p>In a dissection the main instruments are: Scalpel, dissecting scissors, dissection tray, probe, forceps and pins. </p><p>Each of these instruments has a definite function in the dissection: Dissecting tray - Holds the specimen and contains a layer of wax to pin the sample in position. Scalpel - Makes the initial incision. Is also used to cut through structures. Dissecting scissors - Used to complete the incision and to cut structures. Forceps - Used to hold structures so that they can be moved or cut. Probe - Used to move structures or point to structures. Pins - Used to position the specimen or hold the incision open for examination of internal organs.</p><p>Investigative Question: How does the arrangement of a frog’s organ systems facilitate their interactions? PART A:External Features of A FROG</p><p>1. Place the frog in the dissection tray. Rinse with tap water to remove most of the preservative chemicals.</p><p>2. Examine both the dorsal (back) side and the ventral (under) side of the frog. Make note of the following external features:</p><p>Skin : Does the colouration of the frog have a function? Does this play a role in the survival of the frog? ______Eyes: Are the eyes similar to the human eye? ______Legs: Are the fore-legs the same as the hind-legs?______What additional feature is seen on the hind-legs?______Backbone: Does it feel as though the frog has a backbone? ______Mouth: Comment on the size of the frog’s mouth ______Nose: Does the frog have nostrils? _____ What does this tell you? ______What is the round structure observed on the side of the frog behind the eye? ______and what is it’s function? ______</p><p>PART B: Making Incisions</p><p>1. Place the frog in the dissection tray with the ventral side facing up. Use the pins to pin it into position in the wax which is in the dissection tray.</p><p>2. Use the forceps to lift the frog’s skin on its ventral surface. Use the scalpel to make a small incision (about 1 cm) in the middle of the abdomen. </p><p>3. Use the dissection scissors to make the incisions as shown on the diagram right. Be careful to cut ONLY the skin. Pin the flaps to the dissection tray.</p><p>4. Make a vertical incision through the abdominal muscle. Begin your incision with the scalpel. Continue the incision with the dissection scissors up the midline to a point just behind the forelegs.</p><p>5. Use the scissors to cut through the chest bones. Hold the scissors with the rounded blade down and be careful not to cut too deeply or you may damage the heart and lungs and other internal structures. </p><p>6. Use the forceps to separate the muscle flaps from the internal structures. Pin the muscle flaps back far enough to allow easy access to internal organs.</p><p>PART C: Internal Examination</p><p>1. The first organs visible are the heart and liver. The lungs may also be visible. Locate them on the diagram of the frog. 2. The heart and liver cover many of the organs below. Use the forceps and probe to pick up the liver and hold it to the side. Use the labeled diagram below to find the organs of the digestive system. Draw and label as many of these organs as possible. Hint: The pancreas is a thin yellowish ribbon.</p><p>3. Examine the heart, Trace the blood vessels to and from the heart. Notice that the heart of the frog has 3 chambers (2 atria and 1 ventricle). How does this differ from the human heart? ______</p><p>4. Observe how many small arteries are attached to the organs of the digestive system. What is occurring in the Digestive System that would account for this number?</p><p>5. Examine the lungs. Describe the texture of the lung tissue:______</p><p>Can you see any blood vessels going into and out of the lungs? ______</p><p>Why is it important for the blood to go to the lungs? ______</p><p>Is there any other way that a frog gets oxygen into its body? ______</p><p>Could this explain the small size of the frog’s lungs? ______</p><p>6. Attempt to see some parts of the Reproductive and Nervous Systems.</p><p>7. Dispose of your frog properly, according to the teacher’s instructions.</p><p>8. Clean all equipment, including the dissection tray, with soap and water. Dry everything with paper towels.</p><p>9. Put all equipment away in the proper place. Make sure your working surface is clean Analyze and Interpret:</p><p>1. Where is the frog’s heart compared to its lungs? ______</p><p>How do the locations of these organs affect interactions between the frog’s Respiratory and Circulatory Systems?</p><p>2. What important gas must be brought to all tissues by the blood? ______</p><p>What waste gas must be carried away from all tisues by the blood? ______</p><p>3. Describe how the frog’s Circulatory and Digestive Systems are physically connected.</p><p>4. Can the cells of the frog’s tissues survive without receiving nutrients? ______</p><p>5. What are three important nutrient groups that the blood must carry from the Digestive System to all tissue cells? ______, ______, ______.</p><p>Conclusions:</p><p>1. Explain why the interaction of the Respiratory and Circulatory Systems is essential for the frog’s survival.</p><p>2. Explain why the interaction of the Digestive and Circulatory Systems is necessary for the frog’s survival.</p><p>3. Which of these 3 systems acts as a link with the other systems (ie: which system interacts with both of the other 2 systems)? </p><p>4. The frog is a cold-blooded animal. What does this mean? How would this determine the seasons when the frog is most active and least active? (You are going to have to do some research)</p>