Download Topic 6.4 Notes

Topic 6 & 11:
Human Physiology
6.4 Gas exchange
Draw, label, and annotate the
ventilation system + alveoli diagram
Teachpe.com
1 - Ventilation
Read & Consider 6.4.1, 6.4.4 - 6.4.6
• What do you know?
• What questions do you have?
Ventilation System
In larger organisms not every cell has access to oxygen
sources so a ventilation system is needed to maintain a
concentration gradient in alveoli.
RESPIRATION
Muscles  Ventilation
Inspiration –
• The diaphragm contracts and flattens
downwards
• External intercostal muscles contract, pulling
ribs up and out  this increases the volume
of the thorax
• Increased volume decreases the pressure of
alveoli and air flow in to equalize pressure
• Forced inspiration: accessory neck muscles
contract to increase volume
Expiration Passive 
• Diaphragm relaxes and curves upward.
• External intercostal muscles relax, allowing ribs to fall
and decreasing the volume of the thorax
• This increases the pressure in the alveoli pushing air out
of the lungs.
• During forced expiration (exercise) internal intercostal
muscles and abdominal muscles contract for force
exhalation.
PRESSURE ANIMATION -
2 - Exchange
Read & Consider 6.4.2 – 6.4.3
• What do you know?
• What questions do you have?
Gas Exchange Diffusion of gases; process of swapping one gas for another.
 O2 & CO2
1. Alveoli – O2 diffuses into the blood from the alveoli and
CO2 diffuses from the blood to the alveoli
2. Tissues – O2 diffuses from blood into the cells and CO2
diffuses from cells to the blood.
Pneumocytes
Type I
• Extremely attenuated
(25nm)
• Cover 97% of alveolar
surface
• Organelles gathered near
the nucleus
• Vesicles to clear
contaminates
Type II
• Cuboidal in shape
• 60% of total cells, but <5%
of surface area
• Production and secretion of
surfactant
• Act as alveolar stem cells
Increasing Diffusion 
Exchange occurs over the body surface or
respiratory surface. Diffusion requirements:
• Large SA:V  in-foldings (lungs or gills)
• Permeable
• Thin  efficient up to 1mm thickness
• Moist  O2 and CO2 diffuse in solution
• Transport system  maintain a
concentration gradient
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Alveoli
Disease
Emphysema
Lung Cancer
Practical
How does vigorous exercise affect ventilation rate and
tidal volume in humans?
• "Advanced Practice Providers." SIU School of Medicine. SIU School of
Medicine, n.d. Web. 24 Oct. 2014.
• Bishop, Adrian. "Lung Cancer Tumours in Smokers Have 10-times
More Genetic Mutations." Earth Times. N.p., n.d. Web. 24 Oct. 2014.
• "Laboratory Manual for Exercise Physiology: Pulmonary Function
Testing a Valuable Diagnostic Tool." Human-kinetics. N.p., n.d. Web. 24
Oct. 2014.
• "Stock Photo - Human Alveoli, Computer Artwork." Human Alveoli,
Computer Artwork. N.p., n.d. Web. 21 Oct. 2014.
• Zyga, Lisa. "Scientists Discover First Multicellular Life That Doesn't
Need Oxygen." Phys.Org. N.p., 7 Apr. 2010. Web. 10 Oct. 2014.
Works Cited