Simple lungs evolved some 450 million years ago in fish. Some evolved into swim bladders and other evolved into more complex structures we call lungs. Paired lungs are the respiratory surfaces in all reptiles (including birds) and mammals. The amphibian lung is a simple, convoluted sac. The lungs are small and do not contribute to the majority of gas exchange. Instead, the skin performs most of the respiration in these animals. Reptiles and mammals do not use the skin as a primary respiratory surface and instead possess lungs with numerous alveoli. Diffusion of gases occurs across the alveolar surface. RAT Obtain your specimen of the rate used in the digestion and circulatory system labs. Open the mouth of the rat wide enough to expose the tubes leaving the pharynx by cutting through the skin, muscle and bone on both sides of the jaw. Locate the external nostrils and the pathway of air from here into the pharynx. the neck region, locate the trachea. Note the position of the trachea relative to the esophagus and note the differences in their structures and how these differences correlate to their functions. Follow the trachea in a posterior direction it branches into two bronchi, each of which enters one of the two lungs. Make a longitudinal cut through one lung to see the branches of a bronchus. Examine the dissected rat lung under the dissecting microscope. Can you see the alveolae? SKETCH what you see, and include it with your lab report. FROG: Obtain your frog. Remove one lung, and make a lateral incision, cutting it in half. Examine it under the dissecting microscope. Can you see the alveolae? Which type of lung, rat or frog, has the greater amount of alveolae per unit area? SKETCH what you see, and include it with your lab report. PIG: Observe the fresh lung of a pig and observe its texture. Locate a bronchus and trace it as far as you can by carefully cutting along its path. Appreciate the fine structure of the lung; a series of tubes terminating in microscopic sacs called alveoli. Locate the various divisions of the bronchi: primary, secondary and tertiary. HUMAN:
Simple lungs evolved some 450 million years ago in fish. Some evolved into swim bladders and other evolved into more complex structures we call lungs. Paired lungs are the respiratory surfaces in all reptiles (including birds) and mammals. The amphibian lung is a simple, convoluted sac. The lungs are small and do not contribute to the majority of gas exchange. Instead, the skin performs most of the respiration in these animals. Reptiles and mammals do not use the skin as a primary respiratory surface and instead possess lungs with numerous alveoli. Diffusion of gases occurs across the alveolar surface. RAT Obtain your specimen of the rate used in the digestion and circulatory system labs. Open the mouth of the rat wide enough to expose the tubes leaving the pharynx by cutting through the skin, muscle and bone on both sides of the jaw. Locate the external nostrils and the pathway of air from here into the pharynx. the neck region, locate the trachea. Note the position of the trachea relative to the esophagus and note the differences in their structures and how these differences correlate to their functions. Follow the trachea in a posterior direction it branches into two bronchi, each of which enters one of the two lungs. Make a longitudinal cut through one lung to see the branches of a bronchus. Examine the dissected rat lung under the dissecting microscope. Can you see the alveolae? SKETCH what you see, and include it with your lab report. FROG: Obtain your frog. Remove one lung, and make a lateral incision, cutting it in half. Examine it under the dissecting microscope. Can you see the alveolae? Which type of lung, rat or frog, has the greater amount of alveolae per unit area? SKETCH what you see, and include it with your lab report. PIG: Observe the fresh lung of a pig and observe its texture. Locate a bronchus and trace it as far as you can by carefully cutting along its path. Appreciate the fine structure of the lung; a series of tubes terminating in microscopic sacs called alveoli. Locate the various divisions of the bronchi: primary, secondary and tertiary. HUMAN:
new_biology_120_manual_summer_2015_(doheny).docx