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.
Lower respiratory system = refers to the larynx, trachea, bronchi, and lungs. The conducting system consists of a series of cavities and tubes (nose, pharynx, larynx, trachea, bronchi, bronchiole and terminal bronchioles) that conduct air into the lungs.The respiratory portion consists of the area where gas exchange occurs: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.he conducting system consists of a series of cavities and tubes (nose, pharynx, larynx, trachea, bronchi, bronchiole and terminal bronchioles) that conduct air into the lungs. The respiratory portion consists of the area where gas exchange occurs: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.