Hemoglobin
Hemoglobin
► Blood
can carry very
little oxygen in
solution.
► Hemoglobin is required
to carry oxygen
around.
► Hemoglobin is found in
red blood cells
Hemoglobin
► In
fact if the body had
to depend upon
dissolved oxygen in
the plasma to supply
oxygen to the cells –
► The heart would have
to pump 140 liters per
minute - instead of 4
liters per minute.
Hemoglobin
► Each
red blood cell can
carry about one million
molecules of oxygen in
its lifetime
► Hemoglobin is 97%
saturated when it
leaves the lungs
► Under resting
conditions is it about
75% saturated when it
returns.
Hemoglobin
► Hemoglobin
is made from two similar
proteins that "stick together".
► Both proteins must be present for the
hemoglobin to pick up and release oxygen
normally.
► One of the component proteins is called
alpha, the other is beta.
Hemoglobin
► Blood
cells are made up of two components.
► The hemoglobin is in solution inside the
cell.
► The cell is surrounded by a membrane that
holds in the hemoglobin.
► A rough analogy would be a rubber water
balloon.
► The rubber would be the membrane, and
the water would be the hemoglobin
Porphyrin Ring
►
►
►
►
At the core of the molecule
is porphyrin ring which
holds an iron atom.
An iron containing
porphyrin is termed a
heme.
This iron atom is the site
of oxygen binding.
The name hemoglobin is
the concatenation of heme
and globin
Hemoglobin
► Hemoglobin
is a remarkable molecular
machine that uses motion and small
structural changes to regulate its action.
► Oxygen binding at the four heme sites in
hemoglobin does not happen
simultaneously.
► Once the first heme binds oxygen, it
introduces small changes in the structure of
the corresponding protein chain.
Hemoglobin
► These
changes nudge the neighboring
chains into a different shape, making them
bind oxygen more easily.
► Thus, it is difficult to add the first oxygen
molecule, but binding the second, third and
fourth oxygen molecules gets progressively
easier and easier.
► This provides a great advantage in
hemoglobin function.
Hemoglobin
► When
blood is in the lungs, where oxygen is
plentiful, oxygen easily binds to the first
subunit and then quickly fills up the
remaining ones.
► Then, as blood circulates through the body,
the oxygen level drops while that of carbon
dioxide increases.
Hemoglobin
► In
this environment, hemoglobin releases its
bound oxygen. As soon as the first oxygen
molecule drops off, the protein starts changing its
shape.
► This prompts the remaining three oxygens to be
quickly released.
► In this way, hemoglobin picks up the largest
possible load of oxygen in the lungs, and delivers
all of it where and when needed.
Iron and Hemoglobin
►
►
The mineral, iron, plays an
important role in the
body’s delivery and use of
oxygen to and by working
muscles.
It binds oxygen to
hemoglobin, which then
travels in the bloodstream
to locations throughout the
body.
Iron and Hemoglobin
►
►
Generally, the more
oxygen there is being
delivered, the greater the
body’s ability to perform
work.
For this reason, iron
receives much attention
for its role in supporting
aerobic exercise, and it
has been postulated that a
lack of iron in the body
can reduce aerobic
capacity and impair
endurance performance.
Iron and Hemoglobin
► Iron
deficient red
blood cells
► Low number of cells
► Note the hollow and
blanched appearance
of the red blood cells.
Sickle Cell anemia
Sickle Cell Anemia is a
genetic disorder that is
characterized by the
formation of hard, sticky,
sickle-shaped red blood
cells, in contrast to the
biconcave-shaped red
blood cells (RBCs) found in
“normal” individuals.
► This disease is caused by a
mutation in hemoglobin.
►
Thalassemia
►
►
►
It consists of two different
proteins, an alpha and a
beta.
If the body doesn't
produce enough of either
of these two proteins, the
red blood cells do not form
properly and cannot carry
sufficient oxygen.
The result is anemia that
begins in early childhood
and lasts throughout life.
Porphyria
► Porphyria
is a group of
different disorders
caused by
abnormalities in the
chemical steps leading
to the production of
heme
Porphyria
►
It is characterized by extreme
sensitivity to light (exposure to
sunlight causes vesicular
erythema), reddish-brown urine,
reddish-brown teeth, and ulcers
which destroy cartilage and
bone, causing the deformation
of the nose, ears, and fingers.
Mental aberrations, such as
hysteria, manic-depressive
psychosis, and delirium,
characterize this condition as
well.