The Pulmonary System

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The Pulmonary System

• Structure and Function

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Lungs

• Lung tissue weighs 1 kg and covers half a tennis
  court (50-100 square feet)
• Lung tissue is 20-50 times larger than the bodys
  external surface
• Hold 4-6 liters of air.
• Unattached to ribs suspended inside the pleural
  sacs.

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Function

• Ventilation. Breathing (air in and air out)
• Conduction.
• Movement of air through the pulmonary system
• Respiration.
• Gas exchange (O2 and CO2)

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Conduction Zone (humidify, filter)

• Nasal cavity and Pharynx
• Nose moistens, warms, and filters air mouth does
  not.
• Larynx - voice box
• Epiglottis
• Valsalva maneuver

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Conduction Zone (humidify, filter)

• Trachea
• conducting tube (transports air)
• Bronchi
• Branches
• contains muscle, serves to dilate and constrict
• Anatomic dead space

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Respiration

• Bronchioles
• further branching
• Alveolar sacs (300 million)
• Each alveoli is surrounded by a network or
  covering of capillaries.
• Almost forms a sheet of blood.
• At rest, a single blood cell passes by 2 or 3
  alveoli in about 0.5 to 1.0 seconds

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Respiration (gas exchange)

• Occurs through thin walls (0.3 micrometers)
• Diffusion of gases from high to low concentration.

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Types of Respiration

• Pulmonary (external)
• Transfer of O2 and CO2 at the lungs.
• 250 mL of oxygen is exchanged per minute at rest
• 200 mL of CO2 is exchanged per minute at rest
• These numbers can increase up to 25 times during
  heavy exercise
• Cellular (internal) respiration - transfer of O2
  and CO2 in the tissues.

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Mechanics of Breathing
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Pleura

• Pair of membranes (inner and outer) surrounding
  the lungs
• Fluid in between two sacs provides the only
  attachment of the lungs to the thorasic cavity
  (ribs).

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Pleura
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Pleura
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Pneumothroax
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Pressure

• Inspiration
• Air moves into the lungs due to a lower pressure
  inside the lungs
• Expansion of the rib cage and the lowering of the
  diaphragm increase the volume
• As the volume gets larger, the pressure becomes
  lower.

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Pressure

• Expiration
• Air moves out of the lungs due to a higher
  pressure inside the lungs
• Constriction of the rib cage and the raising of
  the diaphragm decrease the volume
• As the volume gets smaller, the pressure becomes
  higher.

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Muscles of Ventilation

• Inspiration
• Rest
• diaphragm and E.IC muscles
• Exercise
• pectorals, scalenes, SCM
• Expiration
• Rest
• no muscles
• Exercise
• abs, I.IC. muscles)

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Lungs and Exercise

• At rest, the blood is 97-98 saturated with
  oxygen
• Exercise, the blood remains 97-98 saturated
• Healthy lungs do not limit a persons ability to
  exercise
• However, respiratory muscles need to be trained
  like any other skeletal muscle