(4)	+Breathing+&+gas+exchange


 * Breathing and gas exchange **

Respiration is the transport of oxegyn from the outside environment to the cells within the tissues and the transport of carbon dioxide from the tissues to the outside environment. At the cellular level, it is defined as the metabolic process where living organisms obtain energy from organic molecules. Basically, it is the act of inhaling oxygen and releasing carbon dioxide through exhaling. In humans and other mammals the respiratory system is consists of the nostrils, airways (trachea and bronchus), the lungs, and respiratory muscles. The lung is located in the chest or the thorax. The thorax is located in the front part of the chest and is surrounded by the ribs. The thorax protects the organs of respiration and circulation. The diaphragm forms the base of the thorax.



 []


 * The human respiratory system consists of: **
 * Nose
 * Nasal cavity
 * Pharynx
 * Larynx
 * Trachea
 * Bronchi and bronchioles
 * lungs


 * The muscles of respiration **

The primary muscles of respiration consists of the external and internal intercostal muscle, and the diaphragm( a sheet of muscle located between the thoracic and abdominal cavities)


 * Intercostal muscle: **

<span style="font-family: Georgia,serif;">The external(outside of the rib cage) and internal(inside of the rib cage) intercostal muscles are group of muscles that help the chest wall move. Both intercostal muscles are located between the ribs. . The external and internal intercostal muscles help to elevate the ribs and sternum. When they pull the ribs up, it will increase the dimension of thoracic cavity, this lowers the air pressure in lungs. This is where the diffusion takes place. The air will move to higher concentration ofair preassure to the lower concentration. <span style="font-family: Georgia,serif;">The internal intercostal muscles are used for exhalation. The external intercostal muscles are used for inhalation. <span style="font-family: Georgia,serif;">

<span style="font-family: Georgia,serif;">As the muscle contracts and shortens, it pulls the ribcage inwards and lifts it, whislt the external intercostal muscles do the opposite. The external intercostal muscles go downward and outward.

<span style="font-family: Georgia,serif;">The main function of the diaphragm is to help the lungs pump the carbon dioxide out and pull the oxygen into the lungs. The diaphragm is a sheet of muscle located between the thoracic and abdominal cavities. The diaphragm provides the main force for breathing. When breathing in, the diaphragm contracts, flattens out, moves down the into the abdomen, this increases the space in chest drawing air into your lungs. When breathing out, the diaphragm relaxes. This does not normally require muscles to work as the lungs are very elastic and when the diaphragm relaxes the lungs simply recoil back to their resting position pushing the air out as they go. The diaphragm, and the intercostal muscles are responsible contracting and expanding the thoracic cavity for respiration.
 * <span style="font-family: Georgia,serif;">Diaphragm **

<span style="font-family: Georgia,serif;">

<span style="font-family: Georgia,serif;">The respiratory system begins with the nose. The nose filters the air that goes into the respiratory system. The nose filtering mechanism prevents particles that should not get inside the respiratory system. The air will be then carried from the nose to the trachea. The trachea will split into the left bronchus and right bronchus. The bronchi continues to divide into smaller passageways called bronchioles, which carries air to functional unit of the lungs, the alveoli. There are over 700million alveoli in the lungs. The oxygen is then transferred to the alveolar walls to the blood cells in capillaries. The waste gas will then diffuse out of the blood cells into the air in the alveoli, to be released upon exhalation as carbod dioxide.
 * <span style="font-family: Georgia,serif;">Written sequence of what occurs: **

<span style="font-family: Georgia,serif;">media type="youtube" key="HiT621PrrO0?version=3" height="283" width="414"

<span style="font-family: Georgia,serif;">Like osmosis, the air moves from high pressure to low pressure. <span style="font-family: Georgia,serif;">When the lungs enlarges the air pressure lowers, this causes higher pressure from atmospheric air to move into the lower pressure lungs. Also when we exhale, the lung pressure increases making the air go out of the lungs and into the lower pressure atmosphere.
 * <span style="font-family: Georgia,serif;">Explanation involving ideas of volume changes and pressure changes… **

<span style="font-family: Georgia,serif;">The diffusion gases occurs when the molecules move from an area with high concentration moves to an area of lower concentration. This takes place during the gas exchange as the blood in capillaries surrounding the alveoli has lower oxygen concentration than the air in the alveoli that had been inhaled. The alveoli and capillaries both have walls that are one cell thick which allows gases to diffuse across them. This also applies with Carbon Dioxide. The blood around the capillaries has higher concentration of carbon dioxide than the inspired air. Thus, carbon dioxide diffuses the opposite way, from capillaries, into the alveoli where it can be exhaled.
 * <span style="font-family: Georgia,serif;">What gases are exchanged? **

<span style="font-family: Georgia,serif;">The gases that we breathe in is about 78.62% nitrogen, 20.85% oxygen, 0.03 carbon dioxide, and 0.05% water.
 * <span style="font-family: Georgia,serif;">How much gas is actually used? **

//<span style="font-family: Georgia,serif;">Composition of atmospheric air and expired air in a typical subject // <span style="font-family: Georgia,serif;">*Note that only a fraction of the oxygen inhaled is taken up by the lungs.
 * **<span style="font-family: Georgia,serif;">Component ** || **<span style="font-family: Georgia,serif;">Atmospheric Air (%) ** || **<span style="font-family: Georgia,serif;">Expired Air (%) ** ||
 * <span style="font-family: Georgia,serif;">N2 || <span style="font-family: Georgia,serif;">78.62 || <span style="font-family: Georgia,serif;">74.9 ||
 * <span style="font-family: Georgia,serif;">O2 || <span style="font-family: Georgia,serif;">20.85 || <span style="font-family: Georgia,serif;">15.3 ||
 * <span style="font-family: Georgia,serif;">CO2 || <span style="font-family: Georgia,serif;">0.03 || <span style="font-family: Georgia,serif;">3.6 ||
 * <span style="font-family: Georgia,serif;">H2O || <span style="font-family: Georgia,serif;">0.5 || <span style="font-family: Georgia,serif;">6.2 ||
 * || <span style="font-family: Georgia,serif;">100.0% || <span style="font-family: Georgia,serif;">100.0% ||

<span style="font-family: Georgia,serif;">Pasted from <[]>

<span style="font-family: Georgia,serif;">Fact: <span style="font-family: Georgia,serif;">The air contains about 21% of oxygen and each day humans take over 20,000 breathes and breathe 35poounds of air. One fourth of air we breathe in is made up of oxygen and the rest is nitrogen (72%), carbon dioxide water vapour and other gases.

<span style="font-family: Georgia,serif;">media type="youtube" key="EFCj9STCvdI?version=3" height="272" width="447"

<span style="font-family: Georgia,serif;">Works cited <span style="font-family: Georgia,serif;">"Human Physiology - Respiration." Human Physiology - Respiration. Harvey Project, n.d. Web. 21 May 2012. <http://people.eku.edu/ritchisong/301notes6.htm>. <span style="font-family: Georgia,serif;">"Introduction to Respiratory & Cardiovascular Physiology." Respiratory & Cardiovascular Physiology. University of the West England, Bristol, 2012. Web. 21 May 2012. <http://hsc.uwe.ac.uk/rcp/rs-v-muscles.aspx>. <span style="font-family: Georgia,serif;">"The Respiratory System." Leavingbio. N.p., n.d. Web. <http://leavingbio.net/Respiratory%20System/THE%20RESPIRATORY%20SYSTEM.htm>.

<span style="font-family: Georgia,serif;">Images <span style="font-family: Georgia,serif;">[] <span style="font-family: Georgia,serif;">[] <span style="font-family: Georgia,serif;">[] <span style="font-family: Georgia,serif;">[]