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Respiratory System Air The air around you is composed of nitrogen, oxygen, carbon dioxide, and trace gases These gases are taken into your body with every breath you take Air Oxygen is so essential to humans that we would be dead without out in only a few minutes. In comparison: - we can live for days without water - we can live for weeks without food Respiration and Breathing Breathing - the movement of air between the external environment and the body - exchange of oxygen and carbon dioxide takes place across a respiratory membrane Respiration - oxygen is supplied to cells and carbon dioxide is transported to the lungs to be expelled Respiration and Breathing Oxygen is used for cellular respiration The concentration of oxygen is cells is much lower than the environment because it is continuously being used Oxygen needs to be constantly replenished for a cell to survive Nasal Cavity Filled with tiny hairs to block particles from entering the system Filled with mucous to also block particles Warm and moisten incoming air Pharynx Air filled cavity at the back of the mouth Trachea Also called the windpipe Covered in cartilage rings to provide structure Lined with mucous producing cells that carry debris using cilia (hair like structures) back to the pharynx Epiglottis The larynx is an enlarged segment of cartilage that supports the epiglottis This flap structure covers the glottis (opening of the trachea) blocks food from entering the lungs When food is chewed, a reflex is sent closing the epiglottis Choking The feeling of choking is when the epiglottis has not closed quickly enough and food or liquid has entered the trachea The resulting coughing is your body’s response and is trying to expel the substance from your trachea to allow breathing to continue Larynx The larynx is also called the voice box - contains two thin sheets of elastic ligaments When air enters, it causes the vocal cords to vibrate Different sounds are caused by change in tension of the chords Protected by thick cartilage called the Adam’s apple Larynx Larger voice boxes lead to deeper voices When you get sick, there is an inflammation of the vocal cords and this causes lower frequency vibrations which causes your voice to lower Laryngitis is extreme swelling and may result in temporary loss of voice Bronchi Air moves from the trachea to the bronchi These branch into the left and right lungs Contain bands of cartilage for structure Bronchioles Smaller branches of the bronchi Do not contain cartilaginous bands Muscles in the walls can decrease diameter Closing of these structures slows air movement leading to a wheezing sound Alveoli Air moves from the bronchioles to the alveoli (sg: alveolus) Each alveolus is surrounded by capillaries Gas exchange occurs here Oxygen and CO2 move from areas of high concentration to low concentration → O2 moves into blood and CO2 moves into alveolus Alveoli The lung contains about 150 million alveoli During inhalation, alveoli look bulb shaped but during exhalation, they collapse The membranes do not stick together because there is a film of fat called lipoprotein that allows them to pop open during inhalation Pleural Membrane A thin membrane that surrounds the outer surface of the lung and lines the inner wall of the chest cavity The space between pleural membranes is filled with a small amount of fluid that reduces the friction between the lungs and the chest cavity Sometimes fluid can build up between these membranes making it very hard to breathe Breathing & the Diaphragm Pressure differences between the air and the chest cavity determines the movement of air into and out of the lungs Atmospheric pressure is relatively constant but the pressure in the chest cavity may vary Gases move from areas of high pressure to areas of low pressure Breathing & the Diaphragm When you inhale, the pressure inside the lungs is less than the atmosphere When you exhale, the pressure inside your lungs is greater than the atmosphere The diaphragm is a dome shaped muscle that separates the thoracic (chest) cavity from the abdominal cavity Breathing & the Diaphragm This muscle contracts during inhalation and expands during exhalation The diaphragm is assisted by the intercostal muscles that cause the ribs to move Breathing & the Diaphragm A pneumothorax occurs when there is an accumulation (build up) of air inside the chest space between the pleural membranes and this causes the lung to collapse Air must be removed so that the lung can re-expand and this is sometimes accomplished by piercing the side with a needle Questions Page 287 #1, 2, 4, 9