Comparison of the avian 'unidirectional' respiratory system (a) where gases are exchanged between the lungs and the blood in the parabronchi, and the bidirectional respiratory system of mammals (b) where gas exchange occurs in small dead-end sacs called alveoli (From: West et al. 2007).s a result, air coming into a mammal's lungs is mixed with 'old' air (air that has been in the lungs for a while) & this 'mixed air' has less oxygen. So, in bird lungs, more oxygen is available to diffuse into the blood (avian respiratory system).
The Power of Sympathy or The Triumph of Nature (1789) is a cautionary novel by William Hill Brown (1765-1793). It is based on an actual case of seduction and incest in col â¦ onial America. It is considered by many to be the first American novel.
Sympathy Cards About Mom Sample 1. Your mom was a beautiful person, inside and out, and she will be sorely missed.. Sympathy Cards About Mom Sample 2. Extending my deepest sympathy on the loss of your mother and praying that your faith will give you strength in this sad time.. Sympathy Cards About Mom Sample 3. Your mother was the kindest and gentlest woman I have ever met.