Lipid metabolism: Difference between revisions

'''Lipid metabolism''' is the synthesis and degradation of [[lipid]]s in cells, involving the breakdown and storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of [[cell membrane]]s. In animals, these fats are obtained from food and are synthesized by the [[liver]].<ref name="MM_Lipid_metabolism">{{cite news | url = http://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/lipid-disorders/overview-of-lipid-metabolism|title=Overview of Lipid Metabolism|newspaper=Merck Manuals Professional Edition|access-date=2016-11-01}}</ref> Lipogenesis is the process of synthesizing these fats.<ref name="chemistryexplained.com">{{cite web | url = http://www.chemistryexplained.com/Hy-Kr/Hydrolysis.html | title = Hydrolysis – Chemistry Encyclopedia – structure, reaction, water, proteins, examples, salt, molecule | work = chemistryexplained.com | access-date = 2016-11-01 }}</ref><ref name = "Freifelder_1987">{{cite book | last1 = Freifelder | first1 = David | name-list-style = vanc | title = Molecular biology | date = 1987 | publisher = Jones and Bartlett | location = Boston | isbn = 978-0-86720-069-0 | edition = 2nd | url-access = registration | url = https://archive.org/details/molecularbiology00davi }}</ref> The majority of lipids found in the human body from ingesting food are [[triglycerides]] and [[cholesterol]].<ref>{{cite book | last1 = Baynes | first1 = Dominiczak | name-list-style = vanc | title = Medical Biochemistry | date = 2014|publisher=Saunders, Elsevier Limited|isbn=978-1-4557-4580-7|pages=121–122}}</ref> Other types of lipids found in the body are [[fatty acid]]s and [[membrane lipids]]. Lipid metabolism is often considered the [[digestion]] and absorption process of dietary fat; however, there are two sources of fats that organisms can use to obtain energy: from consumed dietary fats and from stored fat.<ref>{{cite journal | vauthors = Arrese EL, Soulages JL | title = Insect fat body: energy, metabolism, and regulation | journal = Annual Review of Entomology | volume = 55 | pages = 207–25 | date = 2010 | pmid = 19725772 | pmc = 3075550 | doi = 10.1146/annurev-ento-112408-085356 }}</ref> [[Vertebrates]] (including humans) use both sources of fat to produce [[energy]] for organs such as the [[heart]] to function.<ref name="Lehninger_2000">{{cite book | last1 = Lehninger | first1 = Albert L | first2 = David L. | last2 = Nelson | first3 = Michael M. | last3 = Cox | name-list-style = vanc | title = Lehninger Principles of Biochemistry | location = New York | publisher = Worth Publishers | year = 2000 | edition = 3rd | isbn = 978-1-57259-931-4 | url-access = registration | url = https://archive.org/details/lehningerprincip01lehn }}</ref> Since lipids are [[Hydrophobic effect|hydrophobic]] molecules, they need to be solubilized before their metabolism can begin. Lipid metabolism often begins with [[hydrolysis]],<ref>{{cite web | last = Ophardt | first = Charles E. | name-list-style = vanc | url = http://chemistry.elmhurst.edu/vchembook/622overview.html | title = Lipid Metabolism Summary | date = 2013 | work = Virtual Chembook | publisher = Elmhurst College }}</ref> which occurs with the help of various enzymes in the digestive system.<ref name="chemistryexplained.com" /> Lipid metabolism also occurs in plants, though the processes differ in some ways when compared to animals.<ref>{{cite journal | vauthors = Wedding RT | date = May 1972 | title = Reviewed Work: Plant Lipid Biochemistry | jstor = 2430826? | journal = [[The New Phytologist]] | volume = 71 | issue = 3 | pages = 547–548 }}</ref> The second step after the hydrolysis is the absorption of the fatty acids into the [[Epithelium|epithelial cells]] of the [[Gastrointestinal wall|intestinal wall]].<ref name="Lehninger_2000" /> In the epithelial cells, fatty acids are packaged and transported to the rest of the body.<ref name="Jo_2016">{{cite journal | vauthors = Jo Y, Okazaki H, Moon YA, Zhao T | title = Regulation of Lipid Metabolism and Beyond | journal = International Journal of Endocrinology | volume = 2016 | pages = 5415767 | date = 2016 | pmid = 27293434 | pmc = 4880713 | doi = 10.1155/2016/5415767 | doi-access = free }}</ref>

 

 

== Lipid digestion ==

 

== Lipid storage ==

Lipids are stored in [[white adipose tissue]] as triglycerides. In a lean young adult human, the mass of triglycerides stored represents about 10–20 kilograms. Triglycerides are formed from a backbone of glycerol with three fatty acids. Free fatty acids are activated into acyl-CoA and esterified to finally reach the triglyceride droplet. Lipoprotein lipase has an important role.<ref>Mechanism of Storage and Synthesis of Fatty Acids and Triglycerides in White Adipocytes | Physiology and Physiopathology of Adipose Tissue pp 101–121 | DOI: 10.1007/978-2-8178-0343-2_8</ref>

 

 

== Lipid metabolism disorders ==

 

== Types of lipids ==