(2) The respiratory system consists of respiratory tract and lung, the respiratory tract is the passage for gas to enter and leave the lung, and the nasal mucosa contains a large number of capillaries, which can warm the cold air when blood flows through the nasal cavity; Nose hair is born in the front of the nasal cavity, which can block dust and bacteria and make the air inhaled clean; The mucous membrane in the nasal cavity may secrete mucus, which can make the dry air entering the body moist.
(3) The lung is the main organ for gas exchange and the main place for gas exchange between human body and external environment.
(4) The respiratory tract consists of nasal cavity, pharynx, larynx, trachea and bronchus. It is the passage for gas to enter and leave the lung, and the pharynx is also connected with the oral cavity. When swallowing food, epiglottic cartilage will cover the entrance of the larynx, so that food can enter the esophagus but not the trachea. When swallowing, the reason why food is difficult to enter the trachea is that epiglottic cartilage can cover the throat in time.
(5) Acute bronchitis and pneumonia are caused by bacteria and viruses. These pathogenic microorganisms enter the lungs through the respiratory tract, then enter the capillaries of the lungs, and follow the blood inside the body.
(6) If patients with acute bronchitis are not treated in time, the virus will further spread and infect the lungs, causing pneumonia, so patients with acute bronchitis should be treated in time.
So the answer is: (1)
(2) respiratory tract; Warm, clean and moist (3) lungs (4) pharynx (5) Acute bronchitis and pneumonia are caused by bacteria and viruses. These pathogenic microorganisms enter the lungs through the respiratory tract, then enter the capillaries of the lungs and follow the blood inside the body.
(6) The virus will further spread and infect the lungs, causing pneumonia.