Final answer:
COPD stands for chronic obstructive pulmonary disease, which is a lung disease characterized by chronic poor airflow. It is usually caused by factors such as smoking and is associated with the breakdown of connective tissues in the lungs, hindering gas exchange.
Step-by-step explanation:
COPD is an abbreviation for chronic obstructive pulmonary disease. It is a lung disease characterized by chronic poor airflow, leading to symptoms such as shortness of breath and a cough that produces phlegm. COPD is usually caused by factors such as smoking and is associated with the breakdown of connective tissues in the lungs, reducing the number and elasticity of alveoli and hindering gas exchange.