excretion - 1 EXCRETION Animals Purpose to remove wastes produced by all the living cells in ones body These wastes are transported through the blood

excretion - 1 EXCRETION Animals Purpose to remove wastes...

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EXCRETION - Animals Purpose - to remove wastes produced by all the living cells in one’s body. These wastes are transported through the blood. Means by which wastes are removed: I. Skin - through the sweat glands in our skin, our bodies get rid of water, sodium chloride (salt) and urea (urea is a protein product composed of waste amino acids – all proteins are made of amino acids). Check the following website for more information on sweat glands II. Lungs - the lungs are the major organs of the respiratory system. Purpose of this system - to remove carbon dioxide from the blood and supply it with oxygen. How this happens: Air enters our bodies through the nasal cavity (nose). Hairs in our noses filter dust and other particles from the air before it goes into our lungs (so don’t get rid of your nose hairs, they are there for a purpose…) . Also, in the nasal cavity (which is pretty large), the air is warmed and moistened before it goes down to the lungs. As the air travels down to the lungs it goes through the pharynx , and trachea. The trachea is made of rings and is lined with a mucous membrane made of cells that have cilia (hair-like structures). The cilia traps additional particles such as pollen, dust, bacteria, etc. that was able to pass through the initial filtering process in the nose. The trachea branches into tubes called bronchi as it enters the lungs. These tubes in turn branch into smaller and smaller tubes, the smallest of which are called bronchioles. At the end of each bronchiole there are clusters of sacs (look like grapes) that are called alveoli. Each lung has millions of alveoli (about 300 million in each human lung), which provide a very large surface area (abut 80 square meters in humans) for gas exchange. The alveoli are in turn surrounded by a very large network of capillaries. Gas exchange occurs between the walls of the alveoli and the capillaries that surround them. How you breathe - The diaphragm, a membrane-like, dome shaped, thin muscle underneath your lungs helps to move air in and out of them. Air moves from an area of high pressure to an area of low pressure. So, when your diaphragm contracts, it moves down, your rib cage moves upward and as a result your chest cavity increases, this in turn causes the air pressure in your lungs to decreases and air moves in. When the diaphragm relaxes, it moves upward to its regular position, your rib cage moves downward, your chest cavity decreases, pressure in your lungs increases and air moves out of your lungs.
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  • Winter '13
  • DavidGrueber
  • Mucus, Nephron

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