Transcript Gas composition - gettingbuggywithit

Gas Exchange
How does the air in our mouth differ from the air
in our alveoli?
Gas exchange on many levels
1. External respiration is the exchange of gas
between alveoli and the blood in the capillaries
of the pulmonary circulation
2. Internal respiration is the exchange of gas
between the blood of the systemic circulation
and the cells of the body.
3. Cellular respiration 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 partial
pressure.
• Gasses will diffuse from an area of high partial
pressure to low partial pressure.
• The air we breathe contains nitrogen, oxygen,
carbon dioxide,
and other trace factors
• The partial pressure of each gas depends on
the
location in the
respiratory system (see
handout) and
the circulatory system
Blood entering
lungs from body:
O2 = 40 mmHg
CO2 = 45 mmHg
Air in alveoli:
N2
O2 = 110mmHg
CO2 = 40mmHg
In which
direction will
each gas
diffuse?
N2
Internal Respiration
• The
partialsuch
pressures
of oxygen
and
carbon dioxide
Why
is there
a difference
in gas
composition
in our
change
on location:
coming
toblood
our lungs
anddepending
from our lungs?
• Blood entering lungs from body:
• O2 = 40 mmHg
• CO2 = 45 mmHg
• Blood entering body from lungs:
• O2 = 95 mmHg
•
CO2 = 40 mmHg
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 CO2 into
the blood and take in more O2
from the blood.
Pause for Thought
• In grade nine, Mrs. Baker left her hometown in
Newfoundland (0m elevation) for Mexico City (2km
elevation).
• Atmospheric (gas) pressure lowers as elevation
increases.
• What difference in gas pressure would you expect
to see in the air and in Mrs. Baker’s blood at that
elevation?
• What would happen to Mrs. Baker’s body over time
if she remained in Mexico City?
Getting the gas from here to there:
Transporting gas from lungs to
body cells.
1. Transport of Oxygen in Blood
• ~1% of oxygen is dissolved in blood plasma
• ~99% of oxygen is carried through blood by
hemoglobin. (When hemoglobin is carrying
oxygen it is called oxyhemoglobin)
THIS IS WHY WE NEED IRON!!!!!!!
• Oxygen is weakly bound to hemoglobin. This is a
good thing!
• Bond between oxygen and hemoglobin becomes
less stable as temperature increases, environment
becomes more acidic, and as oxygen
concentration in the surroundings decreases
(WHERE IN THE BODY DO YOU FIND THESE
CONDITIONS? What happens to the oxygen bound
to hemoglobin in these conditions?)
Hemoglobin changes
shape when oxygen
is bound to it
• REVIEW:
• Conditions that promote the release of oxygen by
hemoglobin are:
• 1
• 2
• 3
2. Transport of Carbon Dioxide in Blood
• 7% of CO2 is dissolved in plasma
• 23% of CO2 travels attached to hemoglobin
• 70% of CO2 travels as bicarbonate ion (HCO3- ) in
plasma
Converting CO2 to HCO3• Step ONE:
• In the red blood cell, the enzyme carbonic
anhydrase converts carbon dioxide and water into
carbonic acid
CO2 + H20
H2CO3
carbonic anhydrase
Converting CO2 to HCO3• Step TWO:
• Carbonic acid dissociates to form bicarbonate and
hydrogen ions
H2CO3
HCO3- + H+
Converting CO2 to HCO3• 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)
Recap: Gas Exchange
1. How does gas go from air we breathe to blood?
2. How does oxygen travel from blood in lungs to a
leg muscle cell?
3. How does carbon dioxide travel from blood in lung
to a leg muscle cell?
4. How does gas go from blood into muscle cell?
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 is
very difficult to remove it
• In carbon monoxide poisoning, oxygen does not get
delivered to the tissues in the body
Group Task 1
• Spend fifteen minutes going through following
problems:
(We will correct answers when everyone is done!)
Individual Task
• Create a concept map that includes all terms and LINKING WORDS.
Use terms below:
Oxygen
Carbon dioxide
Blood
Hemoglobin
Bicarbonate
H+ ion
Partial pressure
Carbonic acid
carbonic anhydrase
Oxyhemoglobin
Gas trasport
Acidic
Red Blood Cell
Muscle Cell
Lung
Plasma
(HINT: Use paper squares to rearrange terms)