Which one of the following acts as lung surfactant?
Phospholipids are compound lipids, they contain in addition to fatty acid and glycerol/or other alcohol eg. sphingosine, a phosphoric acid residue, Nitrogen containing base and other substituents.
a. Phosphatidic acid = glycero phosphoric acid + 2 fatty acid.
b. Ceramide = sphingosine + fatty acid.
a. Phosphatidic acid and phosphatidylglycerol.
b. Phosphatidylcholine — Lecithin: - they are most abound phospholipids of cell membrane and represent a large proportion of the body store of choline
Lecithin = glycerol .acid + phosphoric acid + choline
Dipalmitoyl Lecithin is a very effective surface active agent and a major constituent of the surfactant preventing adherence, due to surface tension, of the inner surfaces of the lungs. Its absence in premature →Leads to respiratory distress syndrome.
c. Phosphatidyl ethanolamine → is cephalin
Cephalin = glycerol + fatty acid + phosphoric acid + Ethanolamine
d. Phosphatidylinositol contain no base but have inositol in its place. They are found in Brain, liver, heart and soybean. It is a precursor of second messengers.
e. Phosphatidylserine: contain the amino acids serine rather than choline.
f. Lysophospholipidseg. Lysolecithin→ contain only one acyl radicalsphosphoacylglycerols→ important in the metabolism and inter conversion of phospholipids.
g. Plasmalogens: constitute 10% phospholipid of Brain and muscles. Structurally resemble Lecithin but posses an ether link on Sn-1-carbon instead of Ester link. The alkyl radical is an unsaturated
h. alcohol. Give +ve reaction when tested for aldehydes with Schiff’s reagent.
i. Sphingomyelins: contain: -
j. =fatty acid + phosphoric acid + choline + sphingosine; deficiency of sphingomyelase→
Niemann pick disease → accumulation of sphingomyelins