What does cephalin mean?
Cephalin is a phospholipid — a fat molecule containing phosphate — that is abundant in the brain and other nerve tissue, which is how it earned its name from the Greek kephalē, meaning 'head'. In modern biochemistry the term usually refers to phosphatidylethanolamine, one of the principal lipids of cell membranes, where it helps form the flexible bilayer that encloses every cell and regulates membrane protein function. Historically, 'cephalin' was used more loosely for a group of related phosphatides distinguished from lecithin, and the word survives largely in older clinical and laboratory contexts, such as the cephalin flocculation test once used to assess liver function. Cephalin is also involved in the chemistry of blood clotting, where negatively charged phospholipid surfaces help activate coagulation factors. Because it is strictly a scientific term, cephalin appears almost exclusively in textbooks, research papers, and medical writing rather than everyday conversation, but it remains a useful example of how anatomical observation gave rise to precise molecular vocabulary.
nounA phospholipid found especially in brain and nerve tissue, now identified chiefly as phosphatidylethanolamine, that is an important component of cell membranes and plays a role in blood clotting.
- A phospholipid, specifically phosphatidylethanolamine, occurring in cell membranes especially of brain and nervous tissue, formerly used as a general term for certain ethanolamine- and serine-containing phosphatides.
"The researchers found that cephalin was abundant in the membranes of the patient's nerve cells."
"Cephalin, along with lecithin, makes up a significant portion of the lipid bilayer in neuronal membranes."
"In the older biochemical literature, the cephalin fraction of tissue lipids was separated from lecithin by its insolubility in alcohol."
Rarely pluralized since it is typically treated as an uncountable mass noun referring to a class of lipid; a plural may appear when distinguishing individual members or types of cephalin.
"Different cephalins vary in their polar head groups and distribution across tissues."
Named after the Greek word for 'head', cephalin was first isolated from brain tissue — the fattiest organ you own.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cephalin
The word cephalin derives from Greek kephalē, meaning 'head', combined with the chemical suffix '-in' used for substances; German biochemists who isolated it from brain tissue coined it in the nineteenth century. It belongs to the same Greek root family as cephalic ('relating to the head') and encephalitis ('inflammation of the brain'), reflecting the substance's discovery in cerebral matter. As biochemical knowledge advanced, the broad early sense narrowed so that cephalin is now generally equated with phosphatidylethanolamine.
How cephalin is actually used
A technical term used mainly in biochemistry, physiology, and medicine. In modern usage it most often refers specifically to phosphatidylethanolamine, whereas earlier literature applied 'cephalin' more broadly to a mixture of phosphatides; historical sources should be read with this shift in mind.
Easily confused with cephalin
Cephalin is a fatty substance (a phospholipid) found in brain tissue, while cephalic is an adjective meaning relating to the head.