Lipids in Health and Disease

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Lipids are molecules containing carbon, hydrogen, oxygen and sometimes phosphorous atoms which play important roles in health and disease. This essay will examine some of these functions and look at how they contribute to health and disease. Triglycerides are lipids that are composed of a glycerol head group linked by an ester linkage to three fatty acid tails formed by condensation reactions. The fatty acid tails can be saturated, in that they contain only carbon to carbon single bonds, or be unsaturated with at least one double bond. The tails can be up to approximately seventeen carbon atoms long giving rise to the molecule’s very hydrophobic (water hating) properties. This hydrophobic nature makes them insoluble and so good candidates for storage functions. Lipids have a lower density than water which also makes them good thermal insulators. Many animals have a thin layer of saturated fats under the skin which helps to minimise heat loss through radiation. This means that they contribute to an animal’s ability to maintain its body temperature by homeostasis. This is more pronounced in animals that are adapted to arctic conditions. Often these animals are much larger and have a thicker layer of fat beneath the skin. The increased size this gives lowers the surface area to volume ratio resulting in a lower effective surface from which heat would be lost. Coupled with more insulation, this means the animal would need a lower respiration rate in order to survive, thus helping to preserve fuel sources. The dense number of carbon to carbon and carbon to hydrogen bonds in lipids makes these molecules energy rich and so they can act as useful fuels. A fuel is any substance that releases energy in a useful form when reacted with oxygen. Hydrolysis of triglycerides by lipase enzymes in adipose tissue releases fatty acids which can be converted to respiratory substrates

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