Biology 201 Dr. Edwin DeMont

1. Biology 201Dr. Edwin DeMont Birds: Reptiles by Another Name St. Francis Xavier University

2. Gas exchange Flight is metabolically expensive. The respiratory system in birds is unique because the connection of air sacs and the lungs creates a flow-through system with maximal efficiency This is not an in-and-out form of respiration; it is an efficient flow-through system with almost no dead air space. St. Francis Xavier University

3. Gas exchange Contraction of flight muscles and movements of the furcula help compress and expand the air sacs to move air through the respiratory system. Air flows from the bronchi to the posterior air sacs, and then with the exhalation, the air moves to the parabronchi. With the next inhalation, that bolus of air moves to the anterior air sacs, and with the next exhalation, out. St. Francis Xavier University

4. Skeleton Filmed live The skeleton of birds is lightweight; most large bones have air spaces, other bones are reduced in size. The flexibility of the neck compensates for use of the forelimbs as wings. When the ankle joint is flexed upon perching, the foot automatically grips the perch. St. Francis Xavier University

5. Lift force Low Pressure The airfoil design of the wings creates a lift force. High Pressure High angles of attack can create ‘stalls’, when the lifting capacity of the wing suddenly decreases. St. Francis Xavier University

6. DVD Video Filmed live Wild Moves: Insights into Animal Physiology Birds: Flying and Gliding www.films.com Several questions will be raised during the video. By the end of the video, you should be able to answer the questions listed on the next slide. St. Francis Xavier University

7. DVD Video 1. What three factors influence the ability of a muscle to generate force? 2. Why are most birds small? 3. How did flight probably evolve in animals? 4. How do birds save energy while flying? 5. What influences the shape of wings? St. Francis Xavier University