nonpolar covalent bond. (physical chemistry). A bond in which a pair of electrons is distributed or shared equally between two atoms. 1  Facebook.2  Twitter.onpolar covalent bond. (physical chemistry). A bond in which a pair of electrons is distributed or shared equally between two atoms. 1  Facebook.
When is a barrel chest a sign of a disease process? Chronic obstructive pulmonary disease (COPD) is the most common instance in which a barrel chest will occur. In these cases, itâs a sign of the lungs being over-expanded. This is caused by the loss of elasticity and results in the person having hyper-inflated lungs.
The cause of COPD is much more clear-cut. Smoking is the main cause and is attributed to about 85 to 90 percent of all COPD deaths. Exposure to air pollution, chemicals, and secondhand smoke can also cause it. In rare cases, a genetic defect called alpha-1 antitrypsin deficiency, or AAT, can lead to COPD.