A noncovalent bond between an electronegative atom (commonly oxygen or nitrogen) and a hydrogen atom covalently bonded to another electronegative atom. Particularly important in stabilizing the three-dimensional structure of proteins and formation of base pair s in nucleic acids.
Introduction[edit] The respiratory system serves three principal purposes in the human body: gaseous exchange; sound production; and assistance in compression of the abdomen. It can be divided into two structural divisions, upper and lower, as well as two functional divisions, conducting and respiratory.
The respiratory system consists of two functional parts: (1) a conducting system to bring the air in, including the nose, pharynx, larynx, trachea, bronchi and bronchioles; and (2) the respiratory portion, the site of gas exchange, including the respiratory bronchioles, alveolar ducts, alveolar saccules, and alveoli.he respiratory system consists of two functional parts: (1) a conducting system to bring the air in, including the nose, pharynx, larynx, trachea, bronchi and bronchioles; and (2) the respiratory portion, the site of gas exchange, including the respiratory bronchioles, alveolar ducts, alveolar saccules, and alveoli.