Delivery of Oxygen to Cells
Higher Human Biology
Chapter 21
Haemoglobin
Haemoglobin is a respiratory pigment which
combines with oxygen and significantly increases
the oxygen-carrying capacity of the blood.
It consists of haem (a compound containing iron)
and globin (a protein made of several polypeptides).
A molecule of haemoglobin contains 4 haem groups
each able to carry a molecule of oxygen.
Haemoglobin molecule showing the 4 haem groups.
Association and Dissociation
• To be effective a respiratory pigment must be able
to combine easily (associate) with oxygen when
the oxygen concentration in the surroundings is
high and rapidly release (dissociate) oxygen when
the surrounding oxygen concentration is low.
• Haemoglobin has a HIGH AFFINITY for oxygen
when the oxygen concentration in the surrounding
environment is high (e.g. lungs) and a LOW
AFFINITY for oxygen when the oxygen
concentration is low (e.g. active cells).
The Combining of Haemoglobin
with Oxygen
• This chemical reaction is reversible
Association
(in lungs)
Haemoglobin + oxygen < ------------------- > oxyhaemoglobin
Dissociation
(in tissues)
Oxygen Dissociation Curve
The Effect of Temperature
Significance
• Large quantities of energy is generated by
inflamed tissues suffering microbial infection.
• The rise in temperature that occurs locally in these
tissues triggers the release of extra oxygen from
haemoglobin.
• This is advantageous since these cells are exactly
where extra oxygen is required for aerobic
respiration.
Fetal Haemoglobin
RED BLOOD CELLS
• THEY ARE PRODUCED IN THE BONE MARROW
FROM STEM CELLS AND LAST FOR 120 DAYS.
• THEY REQUIRE IRON FOR THEIR FORMATION.
• THEY REQUIRE VITAMIN B12 FOR THEIR
FORMATION.
• LACK OF IRON OR B12 RESULTS IN ANAEMIA.
• INTRINSIC FACTOR SECRETED BY THE STOMACH
IS REQUIRED TO AID B12 ABSORPTION.
• LACK OF INTRINSIC FACTOR RESULTS IN
PERNICIOUS ANAEMIA.
Biconcave Shape of Red Blood Cells
HEALTHY RED BLOOD CELLS
(the actual size of a red blood cell is approx 2
micron at the rim by 7 micron in diameter)
PRODUCTION OF RED
BLOOD CELLS.
RED BLOOD CELL
Production of Red Blood Cells
• Red blood cells are produced in the red
bone marrow.
• Red bone marrow consists of stem cells
Red Bone Marrow
Destruction of Red Blood Cells
• A red blood cell lives for about 120 days
• Worn out red blood cells are destroyed by
macrophages by the process of phagocytosis
in the liver, bone marrow and spleen.
• Haemoglobin molecules are broken down
and the iron stored for future use.
• The haem group (minus the iron) are
converted to bilirubin.