16. Type I alveolar cells a. None of the statements is true b. Secrete a chemical known as surfactant c. Allow rapid diffusion of gases through their thin membranes d. Are phagocytic e. Allow rapid diffusion of gases through their thin membranes, secrete a chemical known as surfactant, and are phagocytic

b would be the right answer

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.