the pulmonary system structure and function. lungs lung tissue weighs 1 kg and covers half a tennis...
Post on 19-Dec-2015
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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 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)
Nasal cavity and Pharynx Nose moistens, warms, and filters air;
mouth does not.
Larynx - voice box Epiglottis Valsalva maneuver
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.
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).
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)