(20 13? At the beginning of this year, there were several serious "haze days" in North China, covering a large area and lasting for a long time.

(1)PM2.5 particles can enter the blood through the alveolar wall and capillary wall after being inhaled into the lungs. Therefore, if the smallest particles reach the lung [8], they can enter the blood through two layers of cells, which will lead to problems and even fatal problems in organs such as the heart.

(2) The ingested food passes through the small intestine in the digestive tract and is transformed into nutrients that can be absorbed by the human body, and then enters the circulatory system and is transported to tissues and cells of the whole body. Therefore, in the human body, the main organ that converts food into substance "A" is the small intestine.

(3) Insulin can regulate sugar metabolism. Therefore, if a person's fasting blood glucose concentration is often higher than the normal range, the most likely reason is that his body does not secrete enough insulin.

(4) On sunny days, if you take a "forest bath", not only will the dust in the forest decrease, but the oxygen content in the air will also increase due to the photosynthesis of green plants.

(5) Carbon dioxide produced by brain cells→ capillary network around brain cells → cerebral vein → superior vena cava → right atrium → right ventricle → pulmonary artery → pulmonary capillary network → diffused into alveoli → exhaled.

(6) Green plants can only breathe at night, consuming oxygen in the air and producing carbon dioxide, which is discharged into the air through pores. These potted plants only breathe at night, competing with sleeping people for oxygen in the air, and also producing a lot of carbon dioxide gas, which is discharged into the air through the pores on the leaves, affecting people's health.

For a healthy lifestyle, we can write the slogan: Please quit smoking for the sake of others and our own health.

So the answer is: (1) 2.

(2) small intestine.

(3) insulin.

(4) photosynthesis.

(5) Right ventricle → pulmonary artery.

(6) breathing; air hole

Please give up smoking for the sake of others and your own health.