(2c 14？ Tongcheng county simulation) human metabolic activities such as respiration, digestion and excretion are closely related to the circulatory system, and the relationship between them is Figure 6 1(A, B (1) Complete the process ① His main organ is the small intestine, because: the small intestine is very long, about 5 ~ 6 m, and there are various digestive juices such as intestinal juice, pancreatic juice and bile in the small intestine; There are annular folds on the inner wall of the small intestine, and there are small intestinal villi on the folds, which increases the area of digestion and absorption. There are capillaries and lymphatic capillaries in the villi of small intestine, and the villi wall, capillary wall and lymphatic capillary wall are all composed of a layer of epithelial cells, which is beneficial to the absorption of nutrients.

(i) If the second represents alveoli, then the second represents gas exchange between the lungs and the outside world. In the graph, the section C of curve II represents the change of lung gas volume from large to small, indicating exhalation, which is the change of lung contents during exhalation. When the intercostal muscle relaxes, the ribs move downward due to gravity, which makes the anterior-posterior diameter and T-right diameter of the thorax smaller, while the diaphragm relaxes and the diaphragm top rises, which makes the upper and lower diameters of the thorax smaller.

(m)C refers to metabolic waste, excess water and inorganic salts discharged from the body through the urinary system. This physiological process is called excretion. Urine forms other substances in the urinary system, mainly including glomerular filtration and renal tubular reabsorption.

So the answer is: (1) small intestinal villi;

(i) The outside world; Diastolic period; Exhale;

Urine.