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Class Notes: Gas Exchange & Transport
Gas exchange on many (3) levels
1. _________________________ is the exchange of gas between alveoli and the
blood in the capillaries of the pulmonary circulation
2. ________________________ is the exchange of gas between the blood of the
systemic circulation and the cells of the body.
3. _________________________ is the process by which mitochondria convert and
store the chemical energy of glucose as ATP. O2 is used and CO2 is produced in
this process.
External Respiration
 Gas concentration is measured as _________________________.
 Gasses will diffuse from an area of high partial pressure to low partial pressure.
 The air we breathe contains _________________________________ and other
trace factors
 The partial pressure of each gas depends on the location in the respiratory system
(see handout) and the circulatory system
Internal Respiration
• The partial pressures of oxygen and carbon dioxide in our blood change
depending on location:
• Blood entering lungs from body:
•
Blood entering body from lungs:
•
Remember during cellular respiration, our cells use 02 during ETC and create
CO2 when glucose is broken down.
•
Internal respiration occurs when cells get rid of _________ into the blood and
take in more ___________ from the blood.
Transporting Gas from Lungs to Body Cells
1. Transport of Oxygen in Blood
• ~1% of oxygen is dissolved in ______________________
• ~99% of oxygen is carried through blood by hemoglobin. (When hemoglobin is
carrying oxygen it is called _____________________)
•
Oxygen is weakly bound to hemoglobin. This is a good thing!
•
Bond between oxygen and hemoglobin becomes less stable as:
(WHERE IN THE BODY DO YOU FIND THESE CONDITIONS?
What happens to the oxygen bound to hemoglobin in these conditions?)
2. Transport of Carbon Dioxide in Blood
• 7% of CO2 is dissolved in ______________
• 23% of CO2 travels attached to ____________________
• 70% of CO2 travels as bicarbonate ion (HCO3- ) in plasma
• H+ ions in the blood would greatly decrease the pH (this is BAD for the body)
• To prevent the blood from becoming too acidic, hydrogen ions bind to
hemoglobin.
• When hydrogen ions bind to hemoglobin, oxygen is more easily released (this is
why hemoglobin releases more oxygen when the blood is more acidic)
Carbon Monoxide Poisoning (Good to know)
• Carbon monoxide binds to hemoglobin more easily than oxygen (so if both
carbon monoxide and oxygen are present, hemoglobin will bind to carbon
monoxide first)
• Once carbon monoxide is bound to hemoglobin, it will not come off again
• In carbon monoxide poisoning, oxygen does not get delivered to the tissues in the
body