Kinesiology


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lungs

The Pulmonary System

  • Structure and Function

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 body’s external surface
  • Hold 4-6 liters of air.
  • Unattached to ribs; suspended inside the pleural sacs.

Function

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

Conduction Zone (humidify, filter)

Conduction Zone (humidify, filter)

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

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

Respiration (gas exchange)

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

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.

Mechanics of Breathing

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).

Pleura

Pleura

  • Pneumothroax

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.

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.

Muscles of Ventilation

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

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 person’s ability to exercise
  • However, respiratory muscles need to be trained like any other skeletal muscle

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