HUMB1001 Lecture Notes - Lecture 8: Hemoglobin, Blood Plasma, Heme
Transport of Oxygen
• 1000ml of blood carries 200ml of O2, but only 3ml (1.5%) transported dissolved in
plasma
• O2 is very INSOLUABLE in solution
• To combat the O2 solubility problem, another mechanism is necessary to transport
the required quantities
• O2 is taspoted i a loose heial oiatio ith a itaellula piget,
haemogloblin
Oxygen
❖ The normal Hb concentration in blood is (approximates to
)
❖ to blood carries of
❖ At normal CO (), Hb can carry about ; a huge
improvement on the dissolved in the plasma.
Oxygen: Haemoglobin
• 4 haem molecules act as binding sites for oxygen
• Haemoglobin is fully saturated when carrying its maximum O2 load (4 molecules O2)
• The percentage of haemoglobin saturation in blood can vary from 0% to 100%
• The most important factor affecting the binding of O2 to haemoglobin is
PO2
• The PO2 determines the concentration of O2 physically dissolved in the
blood
• O2 diffuses from the alveoli into the blood plasma
• From here it moves into the RBC to combine with Hb
• Increase PO2 will move the reaction to the right
o because the differences in PO2 between alveolar air & pulmonary
apillay lood, H autoatically loads up with O2 i the lugs
Gas Exchange, Gas Transport and Control of Respiration
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• At the tissues the PO2 gradient determines which direction the O2
is going to diffuse
• O2 diffuses from the Hb → plasma → respiring tissues
• Decrease PO2 will move the reaction to the left
o because the difference in PO2 between tissue capillary
lood ad the espiig ells, H autoatially uloads O2
in the tissue
The Relationship Between Oxygen and Haemoglobin
PO2:
❖ O2 – Hb DISSOCIATION CURVE
❖ Shape of curve is very significant
❖ At low PO2 values (0 – 4 Hg: “teep slope
❖ At high PO2 values (40 – Hg: Flat slope
Small changes in PO2 represent large changes in %
saturation of haemoglobin
Large changes in PO2 represent small
changes in % saturation of
haemoglobin
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The Relationship Between Oxygen and Haemoglobin
PO2:
• O2 – Hb DISSOCIATION CURVE
• PO2: 100 → 40 mm Hg (at rest)
• Releases only 25% O2 from Hb (flat
part of curve)
• PO2: 40 → 20mm Hg (with exercise)
• Releases a further 40% O2 (steep part
of curve)
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Document Summary
Gas exchange, gas transport and control of respiration. The normal hb concentration in blood is (cid:883)5(cid:882)/(cid:883)(cid:882)(cid:882)(cid:882)(cid:1865)(cid:1864) (approximates to (cid:884)(cid:882)(cid:882)(cid:1865)(cid:1864) (cid:2870) (cid:883)(cid:882)(cid:882)(cid:882)(cid:1865)(cid:1864) (cid:2869)) (cid:883)(cid:882)(cid:882)(cid:1865)(cid:1864) to blood carries (cid:884)(cid:882)(cid:1865)(cid:1864) of (cid:2870) At normal co (5. (cid:882) /(cid:1865)(cid:1866)), hb can carry about (cid:883)(cid:882)(cid:882)(cid:882)(cid:1865)(cid:1864) (cid:2870) (cid:1865)(cid:1866) (cid:2869); a huge improvement on the (cid:883)5(cid:1865)(cid:1864) dissolved in the plasma. Po2: the po2 determines the concentration of o2 physically dissolved in the blood, o2 diffuses from the alveoli into the blood plasma, from here it moves into the rbc to combine with hb (cid:1854)+(cid:2870) (cid:1854)(cid:2870) At low po2 values (0 4(cid:1004)(cid:373)(cid:373) hg(cid:895): (cid:862) teep slope(cid:863) At high po2 values (40 (cid:1005)(cid:1004)(cid:1004)(cid:373)(cid:373) hg(cid:895): (cid:862)flat slope(cid:863) Small changes in po2 represent large changes in % saturation of haemoglobin. Large changes in po2 represent small changes in % saturation of haemoglobin. Hb plays a vital role in the total quantity of o2 that the blood can pick up in the lungs.
