BIOL 1082 Lecture Notes - Lecture 19: Myoglobin, Blood Plasma, Carbonic Anhydrase
Document Summary
Circulation and gas exchange ii (reading: concepts: 42. 5-42. 7 in textbook: compare and contrast the lungs of frogs, birds and mammals, in terms of structure and function. The frog"s lungs are a pair of thin-walled sacs connected to the mouth through an opening, the glottis. The surface area of the lungs is increased by inner partitions which are heavily supplied with blood vessels. Frogs ventilate their lungs by positive pressure breathing, inflating the lungs with forced airflow. During the first stage of inhalation, muscles lower the floor of an amphibian"s oral cavity, drawing in air through its nostrils. Next, with the nostrils and mouth closed, the floor of the oral cavity rises, forcing air down the trachea. During exhalation, air is forced back out by the elastic recoil of the lungs and by compression of the muscular body wall. Birds use 8 or 9 air sacs situated on either side of the lungs.
