1. Body Energy Maha Al Kuwari 8E

2. What is the process of exchange of gases in Humans?  Breathing is the process in which the gases are exchanged between the environment and the human body.  Breathing is the main function of the respiratory system.

3. Breathing – Inhaling  The process of breathing is initiated when the diaphragm contracts, which causes the rib cage to move upwards, causing the volume in the lungs to increase.  Consequently, the pressure in the lungs is decreased, So, the air from outside is drawn inside the lungs.  This is called inhalation.

4. Detailed passage of air from outside to the lungs  The trachea is the passageway in which the air (that has approximately 20.4% Oxygen) passes through from the outside of the body, to the lungs, and the other way round.  However, when the air enters the trachea, through the nasal cavity, then the trachea splits into two bronchus, each entering a lung. The bronchus is branched into bronchioles, and then at the end of each bronchiole, there are tiny alveoli.

5. Detailed passage of air from the lungs to the blood  The air that has now reached the alveoli in the lungs will be transferred to our blood capillaries which will circulate our entire body, passing by every single cell.  This is possible since the alveoli have a large surface area, have a lot of capillaries surrounding them, the alveoli has thin walls, which allow the process of gas exchange by DIFFUSION

6. Blood Circulation – The Heart The oxygen rich blood coming from the lungs enters the heart through the pulmonary vein into the left atrium, which pumps the blood to the left ventricle. Then the blood is pumped from the heart to the entire body through the Aorta. After the blood circulates the entire body, it returns to the heart and enters to the right atrium, which will pump the blood to the right ventricle. Then the blood is sent to the lungs through the Pulmonary Artery.

7. What happens to the Oxygen Rich Blood when it is pumped from the Heart?  When the blood is pumped from the heart, and circulates through the body, the oxygen passes from the blood, into the cells by DIFFUSION.  In the cells, the Oxygen breaks down the sugar (C 6 H 12 O 6 ) stored in the mitochondria, to form Carbon Dioxide, Water, and Energy, so this diagram demonstrates what happens in the mitochondria.  The Carbon Dioxide diffuses from the cell into the blood, then goes to the heart, which pumps the blood towards the alveoli in the lungs.

8. Breathing – Exhaling  The air has now reached the alveoli in the lungs, and needs to be exhaled, so the diaphragm relaxes, and the volume of the rib cage decreases, which releases the air inside the lungs.  The air released contains only 16 % Oxygen.

9. Bibliography  "Science Clarified." Respiratory System. N.p., n.d. Web. 13 Oct. 2012..  "The Lungs (Human Anatomy): Picture, Function, Definition, Conditions." WebMD. WebMD, n.d. Web. 13 Oct. 2012.  "INTRODUCTION." INTRODUCTION. N.p., n.d. Web. 13 Oct. 2012..  "How Your Heart Works." HowStuffWorks. N.p., n.d. Web. 15 Oct. 2012.  "Cell Process and Energy." Element. N.p., n.d. Web. 14 Oct. 2012..http://ez002.k12.sd.us/Chapter%20Two%20Science.htm  "Inhalation and Exhalation." Branda's A & P. N.p., n.d. Web. 13 Oct. 2012..