Breathing is the process of moving air into and out of the lungs. The process depends on a muscle called the diaphragm. This is a large, sheet-like muscle below the lungs. Inhaling, or breathing in, occurs when the diaphragm muscle tightens. This increases the size of the chest. This too decreases air pressure inside the lungs. This action allows air and gases to enter the lungs. Exhaling, or breathing out, occurs when the diaphragm muscle relaxes. This decreases the size of the chest. This increases air pressure inside the lungs. This action allows for air to leave the lungs. When you inhale, air enters the respiratory system through your nose and ends up in your lungs, where gas exchange with the blood takes place. What happens to the air along the way? In the nose, mucus and hairs trap any dust or other particles in the air. The air is also warmed and moistened. Next, air passes through a passageway that is connected to the windpipe. The air then finds its way to the lungs. In the chest, the windpipe splits so that air enters both the right and left lung.

What happens in the nose as air passes through to the lungs?

On a busy Friday morning in Manhattan, nine pedestrians suffered bullet or fragment wounds after police unleashed a hail of gunfire at a man wielding a .45 caliber pistol who had just killed a former co-worker. The officers unloaded 16 rounds in the shadow of the Empire State Building at a disgruntled former apparel designer, killing him after he engaged in a gunbattle with police, authorities said. Three passersby sustained direct gunshot wounds, while the remaining six were hit by fragments, according to New York Police Commissioner Ray Kelly. All injuries were caused by police, he said Saturday. One officer shot nine rounds and another shot seven. Police identified the gunman as Jeffrey Johnson, 58, who was apparently laid off from his job as a designer of women's accessories at Hazan Import Co. last year. Johnson, who served in the U.S. Coast Guard in the mid-1970s, had two rounds left in his pistol. It holds eight, Kelly said. Police identified the slain co-worker as Steven Ercolino, 41, who had apparently filed a prior complaint against his assailant, claiming that he thought Johnson would eventually try to kill him. Both men had filed harassment complaints against each other in April 2011, Kelly added. Ercolino was listed as a vice president of sales at Hazan Import Corp., according to his LinkedIn profile. "It's not something that should happen to a loving person like that," said his brother, Paul. "He's going to be so missed by everybody. He was a light of so many lives."

What type of weapon did Jeffery Johnson, the gunman, possess?

When he was at Oxford he had been well known for concealing under a slightly rowdy exterior the highest spirits of any of the undergraduates. He was looked upon as the most fascinating of _farceurs_. It seems that he had distinguished himself there less for writing Greek verse, though he was good at it, than for the wonderful variety of fireworks that he persistently used to let off under the dean's window. It was this fancy of his that led, first, to his popularity, and afterwards to the unfortunate episode of his being sent down; soon after which he had married privately, chiefly in order to send his parents an announcement of his wedding in _The Morning Post_, as a surprise. Some people had come in after dinner--for there was going to be a little _sauterie intime_, as Mrs Mitchell called it, speaking in an accent of her own, so appalling that, as Vincy observed, it made it sound quite improper. Edith watched, intensely amused, as she saw that there were really one or two people present who, never having seen Mitchell before, naturally did not recognise him now, so that the disguise was considered a triumph. There was something truly agreeable in the deference he was showing to a peculiarly yellow lady in red, adorned with ugly real lace, and beautiful false hair. She was obviously delighted with the Russian prince.
What caused the individual in Sentence 4 to be "sent down"?