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*Self-Practice*

Std.10th -Science Part 2

Topic 2: *Life Process in Living Organisms Part-1*

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*Today's Practices*

Answer the following question:

1) Write the sequential names of the organs involved in the human respiratory system.

2) Know the function of each of these organs.

Click on the link below to understand the human respiratory system and watch the video.

https://youtu.be/PlNEabFZ5Qk

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*Body Secrets* Continued ...

*Arjun:* Hay Vasudev!  After yesterday's discussion with you and reading page no. 10 from the textbook, I got a lot of information. But this, instead of resolving my doubts, has created some confusion in my mind. Will you permit me to ask some questions?

*Lord Shrikrushn:* Hey Parth, the emergence of the question is the sign of the root vitality.  You are my favorite friend because you ask questions without hesitation.  Please ask!

*Arjun:* How is energy produced in the body from nutrients?

*Lord Krishn:* Hay Parth, first note that energy is not generated from all nutrients. Mainly carbohydrates and fats produce energy. About 60 to 80% of the energy in our body is generated from carbohydrates.

*Arjun:* It's correct.  That is why our diet is high in cereals.  But how does energy come from carbohydrates?

*Lord Krishn:* This is a complicated process.  Before we can understand that, we need to know how the human digestive system and respiratory systems work. I am going to summarize this process in short. 

🔹 *Digestive system*

Food contains complex carbon compounds.  The digested food enters the small intestine after being processed by many enzymes in the stomach and pancreas.   There is a network of many blood capillaries in small intestine. Through them the nutrients in food are absorbed into the blood.  This process is called as 'absorption'.  These substances absorbed into the blood are transported to other parts of the body through red blood cells.  In this way, nutrients are delivered to every cell in our body, counting more than tens of millions.  These nutrients are stored in the cell.

 🔹 *Respiratory system*

No energy is produced from the accumulated nutrients in the cell unless they are oxidized.  Oxidation requires oxygen. This oxygen reaches every cell through the process of respiration. Respiration of living beings takes place at two levels namely body level and cellular level. In case of body level respiration, after breathing the air it reaches to the air sacs in the lungs.  There is a network of blood capillaries around the air sacs. Oxygen and carbon dioxide are exchanged there. By diffusion, oxygen from the air is absorbed into the blood. Red blood cells carry oxygen molecules to the left atrium of the heart.  From there, oxygen is carried throughout the body through the left ventricle and aorta. At the cellular level oxygen is accepted by the cells. Carbohydrates already accumulated in the cells are oxidized with or without oxygen, and in that process energy is released. The released energy is stored in the cell itself in the form of ATP and is used when needed.

*Arjun:* Hey Devkinandan, this whole process came to my notice. But can you explain in detail how energy is generated from the burning of carbohydrates?

*Lord Krishn:* Hey Parth, I am happy to see your curiosity.  But today we are going to stop here. I will definitely answer your question tomorrow.  Until then, if possible, read carefully page No.13 and 14 from science textbook, so that you can easily understand tomorrow's discussion.

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