Introduction:

Each minute we take multiple breaths, and don't even realize it. If you take a second and realize how many breaths and how important it is to breath, it makes you realize it even more. One of the worst feelings in the world is not being able to breath. The respiratory system is a very important system in the body. Every part of the body needs oxygen, and the lungs help to deliver that oxygen. There is more to the respiratory system then just the lungs. Capillaries, lungs, and bronchial tubes are just a few parts of the respiratory system. Many factors affect the way we breath as well. Pressure in the air, the composition of the gases we are inhaling, and exercise are just a few aspects that would affect the way we take breaths. Taking care of our lungs is essential to maintain a healthy body, for our whole life. Understanding ways to keep the lungs healthy, and how the respiratory system works will only benefit you in your life.

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Concept #1: Structure of the respiratory system

When someone says what makes up the respiratory system, most people just assume it's the lungs. There is much more to the respiratory system then just the lungs. Gas exchange is one of the main functions of the respiratory system. The exchange of gases occurs in the alveoli, which are tiny, microscopic air sacs. The alveoli consists of two different kinds of cells. Type 1 makes up most of the surface area of the lungs and this is where most of the gas exchange with the blood is. Type 2 of the alveolar cells secrete the very important surfactant. Surfactant helps to prevent a fluid back up in the lungs. The alveoli spread out to have a surface area of approximately 760 square feet. There are two different zones that the air passes through in the repiratory system. The respiratory zone is the place where gas exchange happens and includes the respiratory bronchioles. The conducting zone is made up of all the anatomical structures the air passes through before it reaches the respiratory zone. The bronchioles are like branch like throughout the lungs. The air passes through the terminal bronchioles and then into the left and right bronchioles. The flow of air into the lungs starts with the nose or the mouth and goes into the pharynx and then into the trachea. From the trachea the air flows through the primary bronchi and keeps going until it reaches the alveoli. No matter what temperature or how dry the air may seem when you inhale it, when the air reaches the respiratory zone it's now at body temperature and full of water vapor. Mucous helps to trap any foreign particles that are unwanted in the lungs. Each breath we take, all of this happens and more. This complex process has been happening since we took our first breath.

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Concept #2: Pressure and volume of the lungs

The lungs are located in the thoracic cavity of the body. Within this cavity, there is a space between all the organs. Pressures inside the lungs and in the atmosphere can cause inspiration, or breathing in. The atmosphere has a certain pressure, as well as the lungs. When the atmosphere's pressure is greater then the pressure of the lungs, inspiration occurs. The pressure in the atmosphere usually doesn't change, so in order for inspiration to happen, the pressure in the lungs must change. On other other hand, expiration, or breathing out, happens when the pressure in the lungs is greater then the pressure in the atmosphere. The lungs can easily expand because of all the elastin. When the lungs expand, the walls of the thoracic cavity go in the other direction of the lungs. Inspiration causes the volume of the lungs to get larger. There are many different times when breathing can vary. For example, while exercising, working, watching tv, or sleeping can all affect the rate of our breathing. The amount of air you breath in, in one breath is the tidal volume. When exhaling, the maxium amount that can be exhaled forcefully is vital capacity. Vital capacity is equal to inspiratory reserve volume, tidal volume, and expiratory reserve volume all added up together. Even when you try to breath out as forceful as you can, there is still air left in the lungs. The amount of air that if left in the lungs, after a forceful expiration is called the residual volume. When quietly breathing, and not forcefully exhaling, the amount of air left in the lungs is then called expiratory reserve volume. When exercising the number of breaths taken per minute is greatly increased. There are ways of measuring the capacity of the lungs, but using some of the terms above. The pressure of the lungs can't get too high or too low. Also the volume of the lungs needs to stay at normal amount in order for breathing to be normal. If any of these get too out of place, breathing is not kept at equilibrium.


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Concept #3: Regulation of breathing

The respiratory system doesn't just work by itself to acheive it's goals. The regulation of breathing is also controlled by the brain. There are nerves located all over the respiratory system that send messages to the brain. The brain has receptors that can control breathing in two different ways. The first way is voluntary breathing, and the second is involuntary breathing. The involuntary, unconscious breathing is affected by the feedback from receptors to the levels of partial pressure of carbon dioxide, the levels of acidity, partial pressure of oxygen of the arterial blood. There are centers in the brain that help to control expiration and inspiration. The medulla oblongota and the cerebral cortex have neurons that send messages to the respiratory system. There are motor neurons that stimulate respiratory muscles that are located in the spinal cord. The rythmicity center which control automatic breathing is located in the medulla oblongota. The pons may also influence the rythmicity center. There are two main areas of the pons that have control over breathing. The apneustic center seems to promote inhalation by stimulating certain nerves in the medulla. The pneumotaxic center appears to have the opposite affect as the apneustic center and that it inhibits inspiration. Chemoreceptors are another automatic control of breathing. The interstitial fluid of the brain, the cerebrospinal fluid, partial pressures of carbon dioxide, partial pressures of oxygen, and the pH of the blood are sensitive to the chemoreceptors. There are receptors also located in the brain, and also in the aortic and carotid arteries. When the body gets the message that it needs to inspire, it's because those receptors are sending messages to the right nerves. If the message isn't received to breath in, your body may not breath in. With the help of all these nerves, receptors, the brain, and much more, the lungs are able to complete their responsibility to the body.

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Application:

There are so many factors in the world that affect the way the respiratory system works. The pressure and gas concentration in the atmosphere have a large impact on the way the respiratory system works. Even though you can't see the make up of the air, alot of the time it's bad. Whether it's from exhaust, smoke, or chemicals, there are so many harmful things we breath in everyday. There are so many people in the world that smoke. As a nurse, being able to educate people on how to quit smoking or ways to improve their lung function is vital. Understanding how important the lungs are and the functions of the respiratory system are key as a healthcare worker. Chronic obstructive pulmonary disease is a common disease in people. Being able to explain that it's a narrowing of airways, destruction of alveolar walls, and chronic inflammation would help me as a nurse. In my personal life, I smoked cigarettes for ten years, and now am smoke free. I will be able to talk and help my patients on a personal level.

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Essential question:

Ventilation is possible due to many factors. The pressure in the atmosphere needs to be greater then the pressure in the lungs in order for inspiration to happen. When the pressure in the lungs is less then the pressure in the atmosphere, expiration occurs. The differences in pressure help aid the respiratory system to acheive ventilation. Boyle's law says that the volume of a gas is inversely proportional to the pressure of a given quantity of gas. When the lungs increase in volume, the intrapulmonary pressure decreases to the subatmospheric levels, so then air goes causing inhalation. When the volume of the lungs decreases, and causes the intrapulmoary pressure to increase, then exhaling the air from the lungs. When the volume of the thoracic cavity changes, it causes the volume of the lungs to change. The muscles of the thoracic cavity also help to aid in respiration. The diaphragm is a large muscle located beneath the lungs. When the diaphragm moves up, expiration occurs because the diaphragm pushes up on the lungs. During inspiration the diaphragm moves down which allows for the lungs to fill up with air. The lungs are located underneath the rib cage, which contains muscles in between each rib. The external intercostals, and the internal intercostals are the two layers of muscles in the ribs. The intercostal muscle help respiration because when inhaling, they move the ribs outwards, and then inwards during expiration. To move the thoracic cavity up to let more air in, the scalenes, pectoralis minor, and sometimes the sternocleidomastoid muscles help acheive that goal. Because of the teamwork of all these muscles respiration becomes easier. These muscles also help to control the amount of pressure in the thoracic cavity and in the lungs.

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References from top to bottom:

http://www.umdnj.edu/idsweb/idst3400/lung_animated.gif

http://www.youtube.com/watch?v=HiT621PrrO0

http://www.odec.ca/projects/2005/thog5n0/public_html/lungs.jpeg

http://www.merckmanuals.com/media/home/figures/MMHE_04_038_03_eps.gif

http://www.youtube.com/watch?v=Mf8xTqfspp4&feature=related

http://thumbs.dreamstime.com/thumb_502/12734499658553M0.jpg

http://thumbs.dreamstime.com/thumblarge_156/1182047488HJRl7M.jpg

http://www.beltina.org/pics/breathing.jpg

http://www.youtube.com/watch?v=SWJHSTAWTCk&feature=related