Some of the food items that are identified as lipids are oils, butter etc. Food items rich in lipids are eggs, meat, nuts and seeds. We need fat in diet to keep our body healthy and to perform body, vital functions.
Utility of Lipids in Biological System
Energy: A major function of fat is to supply an efficient fuel to all tissues except central nervous system and brain, which depends on glucose.
Thermal insulation: The body fat underneath the skin regulates/controls body temperature.
Vital organ protection: A web-like padding of adipose fat surrounds many vital organs such as kidney, protecting them from mechanical shock and providing a supporting structure.
Nerve impulse transmission: Fat layer surrounding nerve fibers provide electrical insulation and transmit nerve impulses.
Tissue membrane structure: Major constituent of cell membrane structure, which is vital for transport of molecules across membrane.
Cell metabolism: Complexes of fat and protein called lipoproteins carry fat in the blood to all cells.
As precursor substances: Fatty acids and cholesterol are precursor for many important molecules involved in metabolic functions and tissue maintenance.
Emulsifier: Amphipathic lipids such as phosphoglycerides, bile acids act as emulsifiers in our body.
Hormonal and Vitaminogenic: Many of the hormones (sex hormones) and vitamins are of fatty nature. Synthesis of these hormones requires lipids.
Industrial Use of Lipids
Lubrication: Almost all machinery requires lubrication for which lipids is needed.
Cosmetics: Lipids are extensively used in this industry. Volatile lipids are used in perfumes, deodorant, soap etc.
Food flavor Lipids in food is responsible for flavour and other attributes like juiciness, texture etc. You will learn more about this in other units.
Pharmaceuticals: Many of the drugs have lipid base given orally, through injection and applied topically, like synthetic hormones, steroids, ointment and lotion.
Absorbents: Lipids are used to absorb / adsorb colour also. For a better shining, we use polish on our shoes or any other articles, which has lipid base.
Miscellaneous
In addition to their role as energy source/reservoir and as the components of membranes, lipids derivatives do perform some other vital functions Phosphatidylinositol and its phosphorylated derivatives act as intracellular signals to regulate cell structure and metabolism.
Eicosanoids are paracrine hormones, substances that act only on cells near the point of synthesis. Eicosanoids are derived from arachidonic acid, a 20-carbon polyunsaturated fatty acid. There are three classes of eicosanoids:
(a) Prostaglandins: They were first isolated from prostrate gland. They act on tissues by regulating intracellular messenger, cyclic AMP. Different prostaglandins perform different functions such as smooth muscle contraction, regulation of I blood flow and rise of body temperature causing pain and inflammation.
(b) Thromboxanes: Produced by platelets and facilitates clot formation.
(c) Leukotrienes: These are observed in white blood cells and liming of the airway to the lungs. These induce muscle contraction. Overproduction of leukotrienes is responsible for asthamatic attacks.
Role of Eicosanoids in human
- Cardiac function
- Regulation of blood pressure
- Bronchial muscle contraction
- Role in inflammation
- Vascular contraction
- Platelet aggregation
- Gastric secretion
- Intestinal motility
- Renin release, sodium excretion
- Lipolysis
- Luteolysis,
- Uterine contraction.
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