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 bronchi and bronchioles are parts of the 'Conduction Zone' of the respiratory system - allowing the passage of air from the external environment into the lungs where gaseous exchange can take place. The conduction zone is also known as dead space, and no gaseous exchange can take place in this area.