Match up the beginning of the sentences and its appropriate endings: 1. external respiration involves taking oxygen into the body and 2. from the nose and mouth, air flows 3. the trachea divides 4. the respiratory tract is lined with 5. the mucus in the respiratory tract is continually moved 6. during heavy exercises, the depth and rate of ventilation 7. the larynx is also known as 8. each of the two lungs is surrounded 9. the pleural cavities are filled 10. air flows into the lungs when ( a) by cilia; b) increases dramatically; c) by its pleural cavity; d) into the larynx & windpipe; e) the chest wall & diaphragm move to increase the volume of the thorax; f) getting rid of excess carbon dioxide; g) with fluid; h) into the right and left bronchi; i)the voice box or adam’s apple; j) a layer of sticky mucus)

1. e) the chest wall & diaphragm move to increase the volume of the thorax 2. d) into the larynx & windpipe 3. h) into the right and left bronchi 4. a) by cilia 5. j) a layer of sticky mucus 6. b) increases dramatically 7. i) the voice box or Adam's apple 8. c) by its pleural cavity 9. g) with fluid 10. f) getting rid of excess carbon dioxide Explanation: 1. The chest wall and diaphragm move to increase the volume of the thorax during external respiration. This allows for the lungs to expand and take in oxygen. 2. Air flows from the nose and mouth into the larynx and windpipe. 3. The trachea divides into the right and left bronchi, which further divide into smaller branches called bronchioles. 4. The respiratory tract is lined with cilia, which are hair-like structures that help in moving mucus. 5. The mucus in the respiratory tract is continually moved by the cilia, helping to trap particles and keep the airways clean. 6. During heavy exercise, the depth and rate of ventilation, or the amount of air breathed in and out, increases dramatically to meet the higher oxygen demands of the body. 7. The larynx is also known as the voice box or Adam's apple, and it plays a role in producing sound for speaking and singing. 8. Each of the two lungs is surrounded by its own pleural cavity, which is a thin, fluid-filled space that helps to reduce friction during breathing. 9. The pleural cavities are filled with fluid, which further assists in reducing friction and allowing the lungs to expand and contract smoothly during breathing. 10. Air flows into the lungs when the chest wall and diaphragm move to increase the volume of the thorax, creating a pressure difference that allows air to enter the respiratory system. By matching the beginnings and endings of the sentences, we can understand the different processes and structures involved in respiration and how they contribute to the functioning of the respiratory system.