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.
Mammalian lungs are located in the thoracic cavity where they are surrounded and protected by the rib cage, intercostal muscles, and bound by the chest wall. The bottom of the lungs is contained by the diaphragm, a skeletal muscle that facilitates breathing.Breathing requires the coordination of the lungs, the chest wall, and most importantly, the diaphragm.o increase the volume of the lungs, the chest wall expands. This results from the contraction of the intercostal muscles, the muscles that are connected to the rib cage. Lung volume expands because the diaphragm contracts and the intercostals muscles contract, thus expanding the thoracic cavity.