PRACTICAL 12 – LUNG DISSECTION

LUNG DISSECTION

PRACTICAL 12 - ÁNGELA SÁNCHEZ AND SORAYA REVILLA

1. OBJECTIVE

To examine externally and internally the lung and the rest of the airways.

2. MATERIALS

1- Paper straw 2- Lab scissors 3- Tweezers 4- Laboratory knive 5- Paper towels 6- Gloves 7- Pig lungs

3. BASIS

The lungs lie on both sides of the mediastinum which contains the trachea, heart, major blood vessels, nerves and oesophagus. The trachea divides into the right and left main bronchi at the carina, which is close to the aortic arch and the division of the pulmonary artery into its left and right branches. The main bronchi, pulmonary arteries and veins penetrate each lung at the hila. The lobes of the lungs are covered, except at their ‘roots’ at the medial surface, by a thin layer of tissue called the visceral pleura. The mediastinum and chest wall are lined by the parietal pleura. It helps some students to visualize the arrangement of the pleurae by thinking of a plastic bag, full of lungs, inside a second plastic bag, the two bags being the visceral and parietal pleurae.

Once in the lungs, oxygen is moved into the bloodstream and carried through your body. At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide. Your bloodstream then carries this waste gas back to the lungs where it is removed from the bloodstream and then exhaled. Your lungs and respiratory system automatically perform this vital process, called gas exchange. In addition to gas exchange, your respiratory system performs other roles important to breathing. These include: Bringing air to the proper body temperature and moisturizing it to the right humidity level. Protecting your body from harmful substances. This is done by coughing, sneezing, filtering or swallowing them. Supporting your sense of smell.

4. METHODOLOGY

1. Place the lungs over the dissection tray with the anterior side facing upwards. Identify the trachea, which divides into two bronchi entering each lung. Note that the back of the trachea is flat. Observe the lobes that form each lung. Try to observe the pulmonary arteries and veins. Make a sketch of what you observe. 2. Insert a tube down the trachea and blow into the end of the tube. Observe how the lungs swell. 3. Insert the tip of the scissors into the trachea and start cutting in the direction of one lung. Observe the resistance offered by the cartilage. Continue cutting along the bronchi and bronchioles until you can no longer continue. Observe the continuous branching of the bronchioles. Draw a diagram of the inner structure of the lung. 4. With scissors or a scalpel, make a cross section of the lung. Observe and draw what you see.

5. RESULTS

1. RTILAGUE 2. TRACHEA 3. UPPER LOBE 4. MIDDLE LOBE 5. OBLIQUE FISSURE 6. LOWER LOBE 7. APEX 8. BIFURCATION OF THE TRACHEA 9. PRIMARY BRONCHUS 05 10. LOBE BRONCHUS 11. BRONCHIOLES 12. PULMONARY VEIN 13. ALVEOLI 14. LOBE .

• How many lobes does each lung have? Which of the two lungs is larger? Each lung has 3 lobes: upper, middle, and lower. The right lung is slightly larger than the left one. • Why do you think the trachea is cartilaginous? The tracheal cartilage plays an important role in maintaining the mechanical stability of the trachea, as it keeps the trachea open and prevents its collapse under the negative pressures of the respiratory cycle. • Have you observed muscles in the lungs? Look for information and describe the breathing movements. Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs. A respiratory cycle is one sequence of inspiration and expiration.

• Describes the path of an oxygen molecule from the time it enters the lung until it reaches any cell in the body. We breath in the oxygen, which travels all the way through our lungs until the alveoli. Then it is carried by red blood cells throughout the body, only to be exchanged with carbon dioxide at the end of the cycle. • What do cells need oxygen for? Oxygen helps organisms grow, reproduce, and turn food into energy. • How do fish breathe? Fish take water into their mouth, passing the gills just behind its head on each side. Dissolved oxygen is absorbed from the water and carbon dioxide released, which is then dispelled

VS

Lung

Lung

without air

with air

6. observations

In conclusion, we have discovered that our lungs are a much more complex structure than what we initially thought them to be. As well as the fact that the trachea and its inside are filled with little wholes each leading to a different bronchiole and eventually to many alveoli. After having checked with a straw how the air flows into the lungs, we realized how impressive the way oxygen enters our body is. But the most interesting thing was with no doubt how the inside of the lungs looks once its been disectioned.

wikipedia

7. references

https://courses.lumenlearning.com/bio2labs/chapter/reading-fetal-pig-dissection/

https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_II_Laboratory_Manual_(Lumen)/10%3A_Cardiovascular_Respiratory_System_and_Pig_Dissection/10.03%3A_Reading-_Fetal_Pig_Dissection

THE END!