(6)	Respiratory+system++Efficiency+&+cleaning

**Respiratory System** Biological system of an organism which is made up of organs that helps body to breathe by delivering oxygen (O 2 ) to the body but takes away carbon dioxide (CO 2 ).

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**Features that make the respiratory system efficient** **Lungs** **Two lungs** Human has two lungs instead of one, since a lung is used for respiratory system, two lungs would make the effect of respiratory system doubled, and therefore it becomes more efficient [] **Moist membranes** The membranes in the lungs are always kept moist so that it is in good condition for diffusion **Exhalation** **Passive process** Human body does not contract muscle when exhaling (expiration), and this is why the process of exhalation is called passive process (doesn't use energy). However unlike exhalation, the inhalation is active process (uses energy). The diaphragm contracts when inhaling and relaxes when exhaling, and this is called elastic recoil. The elastic recoil makes thoracic volume restored because abdomen is under high pressure when the thorax expand downwards as diaphragm contracts (Tamarkin). **Diagram of inhalation and exhalation (The Mechanism of Breathing)** **__Key words__** **Diaphragm:** muscle that is used to breathe, it is located between lungs and stomach **Thoracic:** relating to or affecting thorax (part of body between neck and waist) **Abdomen:** part of body below chest but where stomach and intestines are

**Note:** exhaling is not passive when exercising such as whistling, playing instruments and blowing balloon as it increases the rate of breathing **Alveoli** **Thin alveoli wall** Walls of the alveoli is where carbon dioxide and oxygen is exchanged, and since its wall is very thin, the distance between air and blood will be short. Therefore the gradient of oxy gen and carbon dioxide's concentration will be very steep and oxygen can be transferred to blood stream with faster speed (Carter). **Diagram of Alveolar-capillary barrier (Alveolar-capillary barrier)** **__Key words__** **Alveoli:** tiny air sacs that are the destination of air breathed in **Capillaries:** smallest blood vessels in our body, they are imbedded in the walls of alveoli

**Large surface area of alveoli** Alveoli increases the size of the lung in order to make more diffusion takes place, so that a greater volume of oxygen and carbon dioxide is transferred in and out of the lungs

**Moist wall** The wall of alveoli is moist, so just like the moist membranes in the lungs, it helps diffusion efficiently and it is suited for efficient gaseous exchange (respiratory system) of body

**Multiple alveoli** Just like two lungs, when there is more than one thing that does the same job, then the work becomes more efficient. Therefore in this case, body carrying multiple alveoli would mean more oxygen is passed through the blood stream hence it is efficient. There's about 300 million to 350 million alveoli in each lung of human, so in total, there's about 600 million to 700 mullion alveoli (two lungs). **How respiratory system is kept clean** **Clearing the Air in the Body** **Cilia** Cilia is small hair in the nose that helps to filter large particles out. Cilia is also found along the air passages, and it performs sweeping motion to keep the passage clean ("How the lungs").

**Mucus** The cells in the trachea and bronchial tube produces mucus, and mucus is along the air passages with cilia. Mucus has function of making air passage moist and aids that stops dust, bacteria and viruses, substance that cause allergy and other kind of substances from coming into the lung ("How the lungs").

**Goblet cells** They are mostly at the lining of respiratory and digestive tracts, they secretes mucus ("What is the function")

**__Key words__** **Trachea:** windpipe in the body **Bronchial tube:** two tubes that connect trachea to the lung

**Diagram of How Respiratory System is Kept Clean**

**Works Cited** //Alveolar-capillary barrier//. N.d. //Wikipedia//. N.p., n.d. Web. 29 May 2012. .

Carter, J. Stein. “Respiratory System.” //Biology//. N.p., 3 Nov. 2004. Web. 29 May 2012. .

“How the Lungs and Respiratory System Work.” //WebMD//. N.p., n.d. Web. 29 May 2012. .

“Inside the Human Body - The Respiratory System.” //The Lung Association//. N.p., n.d. Web. 29 May 2012. .

The Mechanism of Breathing. N.d. //LEAVING CERTIFICATE BIOLOGY//. N.p., n.d. Web. 29 May 2012. .

“THE RESPIRATORY SYSTEM.” //Estrella Mountain Community College//. N.p., 18 May 2010. Web. 29 May 2012. [].

Phoenixfilmandvideo. Respiratory System (2nd Ed., Rev.) (Clip) . Youtube . N.p., 25 June 2008. Web. 2 June 2012. . Tamarkin, Dawn A. “Inspiration and Expiration.” //Springfield Technical Community College//. N.p., n.d. Web. 29 May 2012. .

“What is the function of goblet cells?” //Innovateus//. N.p., n.d. Web. 29 May 2012. .