ARDS

1. ILOS
Explain biochemical role
of phospholipid in ARDS
3

2. Phospholipids
are compound lipids containing
a phosphate radical. 0ne of
phosholipid is Dipalmitoyl-
lecithin, which a very effective
surface active agent,
preventing adherence of the
inner surfaces of the lung
alveoli.

3. (1) PHOSPHATIDIC ACID:
It consists of glycerol esterified with 2 FA,
one of them is usually saturated at the 1
position and the other FA is usually
unsaturated at the 2 position. It contains
phosphoric acid at the three position.

4. (2) PHOSPHATIDYL CHOLINES
(LECITHINS):
- Lecithins consist of phosphatidic acid
esterified with choline.

5. -They are the most important
phospholipids of the cell membrane.
-They represent the body’s store of
choline which is important in nervous
transmission and acts as doner of
methyl groups.
-Dipalmitoyl-lecithin ( lung surfactant ) is
a very effective surface active agent,
preventing adherence of the inner
surfaces of the lungs.

6. LUNG SURFACTANT
This is a substance that
reduces the surface tension of
fluid in the lungs and helps
make the small air sacs in the
lungs (alveoli) more stable. This
keeps them from collapsing when
an individual exhales.

7. HOW IS LUNG SURFACTANT
PRODUCED?
Surfactant is synthesized and secreted by
Type II pneumocytes, also called
alveolar epithelial cells, about 32 weeks
of gestation in the human. It is made up
of 70% to 80% phospholipids,
approximately 10% protein and 10%
neutral lipids, mainly cholesterol.

8. WHAT IS THE MAIN COMPOSITION OF
LUNG SURFACTANT?
Dipalmitoylphosphatidylcholine(D
PPC) is the major phospholipid
component of mammalian surfactant
and is the primary constituent
responsible for lowering surface
tension in the alveoli.

10. Respiratory Distress Syndrome (RDS) is due to
deficiency of surfactant and commonly occurs in
preterm babies. However, the condition can also occur
in term babies and may be due to abnormalities of
surfactant production
A baby develops RDS when the lungs do not
produce sufficient amounts of surfactant. As a
result, a premature baby often has difficulty expanding
her lungs, taking in oxygen, and getting rid of carbon
dioxide .As without normal surfactant, the tissue
surrounding the air sacs in the lungs (the alveoli)
sticks together.
What is the respiratory Distress
Syndrome?

11. Estimation of Lung maturity
Lung maturity of the fetus can be
gauged by determining the ratio of
DPPC to sphingomyelin, usually
written as the L (for lecithin)/S
ratio, in amniotic fluid.

12. A ratio of two or above is
evidence of maturity, because it
reflects the major shift from
sphingomyelin to DPPC synthesis that
occurs in the pneumocytes at about
32 weeks of gestation. Lung
maturation can be accelerated by
giving the mother glucocorticoids
shortly before delivery.