Fetal Hemoglobin Essay Hemoglobin Fetus

Fetal Hemoglobin: Function and Structure
Hemoglobin is found in the red blood cells of every human being, child or adult. It is
necessary because hemoglobin binds and carries oxygen from the lungs to other tissues
within the body. Hemoglobin also transports carbon dioxide from tissues to the lungs. In
fact, hemoglobin represents over 95% of the solid components of red blood cells.
However, a developing baby has fetal hemoglobin while an adult, in most cases, carries
adult hemoglobin.
Fetal Red Blood Cells
A fetus is totally dependent on oxygen from its mother’s lungs and thus, must
acquire a way in which to obtain the needed molecule. The needed oxygen travels around
the mother’s bloodstream attached to hemoglobin molecules in red blood cells. Once at the
 placenta, the oxygen diffuses across into the fetal bloodstream and reaches the fetus at a
much lower pressure than is found in the mother’s blood. The oxygen pressure found in a
fetus’ blood can be compared to the pressure at the top of Mt. Everest, not nearly enough
 pressure for an adult. Ho
w then, can a fetus survive on such low oxygen pressure?
A fetus is able to cope with this low amount of oxygen pressure in several ways:
1.A fetal heart beats extremely fast – an average of 150 times per minute.
A normal adult, on the other hand, has an average heartbeat between 70-
80 times per minute.
2.A fetus has more red blood cells per cubic millimeter than an adult
(seven million compared to five million in an adult!). A fetus’ heart
must beat quickly in order to allow such large amounts of red blood
cells to pick up the much-needed placental oxygen. Keep in mind that it
takes only about 30 seconds for a fetal blood cell to make a complete
trip around the fetus’ body. The number of red blood cells, combined
with the increased heart rate, illustrates just how much oxygen the fetus
3.Fetal red blood cells have a greater affinity for oxygen at a lower 
oxygen pressure than adult red blood cells do.
4.Fetal red blood cells are larger than adult cells (8.3 microns compared to
7.5 microns) and therefore each cell can carry more oxygen.