A) 1 month; 4 years B) 6 months; 3 years C) 1 year; 4 years D) 18 months; 3 years Answer: C Topic: Business Cycle Patterns Skill: Recognition 4) According to the National Bureau of Economic Research, since 1920 the average length of reces-sions has been approximately A) one year. B) a year and a half.C) two years.) 1 month; 4 years B) 6 months; 3 years C) 1 year; 4 years D) 18 months; 3 years Answer: C Topic: Business Cycle Patterns Skill: Recognition 4) According to the National Bureau of Economic Research, since 1920 the average length of reces-sions has been approximately A) one year. B) a year and a half. C) two years.
Lungs and Respiratory System of the Chest The respiratory system of the upper abdomen and chest includes the structures involved in the vital delivery of atmospheric air and the exchange of gases between the body and atmospheric air.
Â© 2014 WebMD, LLC. All rights reserved. The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi.The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic. Emphysema: A form of COPD usually caused by smoking. 2  The fragile walls between the lungs' air sacs (alveoli) are damaged, trapping air in the lungs and making breathing difficult. 3  Chronic bronchitis: Repeated, frequent episodes of productive cough, usually caused by smoking.