(2) The physiological process [2] refers to the gas exchange between the gas in the alveoli and the blood in the capillaries around the alveoli. What about this process? Gas exchange in alveoli; Physiological process [③] refers to the process that nutrients enter the blood after food is digested, so it is called absorption; (3) White blood cells have defense function. Under normal physiological conditions, white blood cells can penetrate the tube wall to reach tissue cells and devour germs; ?
(4) The main function of the kidney is to form urine, which needs to be filtered through the glomerulus and then reabsorbed by the renal tubules. The substance [4] is urine, and its main components are water, urea, uric acid, etc.
So the answer is: (5 points) (1) contraction? (2) gas exchange and absorption in alveoli (3) white blood cells
(4) Water, urea, uric acid, etc