The Mechanism of Breathing Out

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					The Mechanism of Breathing Out
   Diaphragm

 The diaphragm is a thin, dome-shaped sheet of muscle,
  approximately level with the bottom of the ribs, which
  separates the thoracic cavity from abdominal cavity.

 The sheet of muscle is curved upward in the middle, like an
  upside-down saucer.

 As you breathe in, the sheet is pulled downward, which
  makes the cavity larger. This decreases air pressure in the
  lungs, so air rushes into the lungs.
 The intercostals muscles also contract causing the rib cage
  to move upward and outward, which causes air to enter the
  lungs.

 As you breath out (expire) the ribs and diaphragm return to
  their relaxed positions, causing a decrease in thoracic
  volume.
   Lung Capacity
 Tidal Volume = the amount of air moved by a normal
  individual at rest.

 Expiration reserve volume = after a noraml breath, force
  out as much extra air as you can.

 Inspiratory reserve volume = the amount of extra air that
  you can force in at the end of a normal inhalation.

 The total of these = TOTAL LUNG CAPACITY
The Respiratory Capacities of an
        Average Adult
Expiratory Reserve    1500 cm3
      Volume
  Tidal Volume        500 cm3


Inspiratory reserve   2000 cm3
      volume
  Vital Capacity      4000 cm3
   Exchanges of Gases
 As air enters the alveoli in the lungs, oxygen gets dissolved
  in water and crosses the membranes to enter the blood
  stream. This occurs by the process of diffusion.

 As oxygen enters the capillaries, hemoglobin molecules in
  the red blood cells pick up oxygen.

 Each hemoglobin molecule has four sites of attachment.

 Carbon dioxide is released in the opposite direction and
  passes into the alveoli for expiration
 Blood now rich in
  oxygen is then
  transported via the
  pulmonary vein back to
  the left side of the
  heart where it will be
  pumped out to every
  cell in the body for
  cellular respiration.

 While hemoglobin
  transports
  oxygen, there is no
  carrier for carbon
  dioxide and travels the
  blood as carbonic acid.

				
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posted:4/7/2010
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