BIOL 2312 Chapter Notes - Chapter 48: Bronchiole, Partial Pressure, Exhalation
12 Sep 2017
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Nearly all reptiles, birds, mammals, amphibians has lungs. Lungs= site of oxygen diffusion into blood, co2 diffuses out. Direction of gas diffusion is the opposite of that in the respiratory organs. External environment surrounding gas exchange is aqueous --> due to plasma membrane"s need to be surrounded by water. On land, oxygen dissolves in fluid that surrounds the lungs. Gases diffuses passively down the gradients of o2 and co2 on both sides of the membrane and by their relative solubility in the plasma membranes. Oxygen levels needed for cellular respiration can"t be obtained by diffusion over distances larger than . 5 mm. Limits size and structure of organisms that get o2 by diffusion. Create water current-- beating cilia produce the current. New water continuously replaced the depleted oxygen water. This maximizes the concentration difference (delta p) of. Gills, trachea, lungs-- increase surface area for diffusion. Gills= extensions of tissue that project into water.
