Transcript File - twynham a level pe

Transport of Respiratory
Gases
Carbon dioxide in blood
• 5% dissolves in plasma
• 20% combines with haemoglobin
Carbaminohaemoglobin!
• 75% combines with water forming
bicarbonate ion (hydrogen carbonate)
CO2 combines with H2O making it unstable. This releases Hydrogen ions and
this reacts with oxyhaemoglobin to make acid
2
Transport of Oxygen…
• Some oxygen is soluble in plasma (3%)
• Most is carried in haemoglobin, which is
found in red blood cells. (97%)
• Each haemoglobin molecule can carry
•
up to 4 oxygen molecules
Oxygen & haemoglobin =
Oxyhaemoglobin
• This reaction is reversible and
depends on the partial pressures of
oxygen.
• When all the haemoglobin is combined
with oxygen it is said to be fully
saturated (100%)
• This happens where oxygen in the
surrounding tissues is high i.e. lungs.
• At lower concentrations (i.e. in the muscle
tissues), the haemoglobin gives up its
oxygen (dissociates) which reduces its
percentage saturation (75%)
• On returning to the lungs where there is a
higher concentration of oxygen it picks up
more and becomes fully saturated.
Oxyhaemoglobin
disassociation curve
• % saturation of haemoglobin at
different partial pressures of oxygen.
Exercise!
• Exercise produces conditions that
cause haemoglobin to release O2
more readily. Dissociate
• The haemoglobin gives up almost
all of its oxygen.
Myoglobin
• This is another respiratory pigment
that is only found in the muscles.
• It has a higher affinity for oxygen
than haemoglobin.
• It picks up all of the oxygen
molecules released by haemoglobin
taking it into the muscle.
What affects the amount of oxygen
released from haemoglobin at the
muscle?
1) Partial pressure of oxygen CO2
2) In acidic conditions oxygen dissociates
more easily with haemoglobin.
What could cause the blood to be more
acidic???
3) Increase in temperature Exercise
generates heat. Decreases haemoglobin's
affinity for oxygen- more is released more
readily .
Oxyhaemoglobin Dissociation Curve
Amount O2
released
Increased
O2 released
Bohr
shift
pO2 in
muscles
pO2 in
lungs
12
Typical question
Describe how oxygen is transported to the
working muscles and the effect that
strenuous exercise will have on its delivery.
Explain why strenuous exercise has this
effect.
(4 marks)
13
Answer
1. Simplistic circulation – heart – arteries –
muscles;
2. Oxygen as oxyhaemoglobin;
3. Exercise increases temperature;
4. More CO2 in blood/increased acidity;
5. Both increase release of oxygen from
haemoglobin at muscles;
6. Bohr shift;
(4 marks)
14
Typical question
• Explain the causes of the Bohr shift and
how it increases oxygen delivery too the
working muscles
(4 marks)
Typical question
• Where is myoglobin found and what is its
role in the body? (2 marks)
• Carry/ transport oxygen to mitochondria
for respiration
• Found in the muscle cell
Extraction of oxygen
oxygen-rich blood
• Lots of
delivered
to muscles
• Need for muscle to remove oxygen
• Difference between oxygen content of
artery approaching muscle and vein
leaving muscle - concept of a-VO2 difference
• During exercise a-VO2 diff increases
19
a-vO2 diff.
Artery carrying
O2 to muscle
Vein carrying O2
away from muscle
Difference in oxygen
concentrations between artery
and vein = a-vO2 diff.
20
a-vO2 diff.
Artery carrying
O2 to lungs
Vein carrying O2
away from lungs
A-vO2 diff. at
lungs
21
Oxygen into muscles
• Oxygen combines with pigment –
myoglobin
• An oxygen store
• Used in
aerobic processes to make
energy
22
Typical question
During a game, a player’s arterio-venous
difference (a-vO2 diff) will increase.
What is the significance of this increase in avO2 diff to the player?
(3
marks)
Answer
1. Difference between oxygen content of arterial
2.
3.
4.
and venous blood;
During game - more oxygen is needed/used/
extracted by the muscles/lungs;
Used/needed for energy/ATP
production/aerobic/ endurance/stamina
exercise;
Leads to improved performance;