intro to lipid

Lipids are defined as

Organic substances insoluble in water but soluble in organic solvents such as ether and chloroform

Distribution of lipids

Lipids are widely distributed in both animals and plants

Animal sources of lipids

Fats, butter, egg yolk, cream, liver, and brain

Plant sources of lipids

Nuts, peanuts, olive, olive oil, cotton seed oil, sunflower oil, and linseed oil

Energy value of lipids

1 gram of lipids provides 9.3 kcal

Dietary importance of lipids

Provide high energy, essential fatty acids, and fat-soluble vitamins (A, D, E, K)

Structural roles of lipids

Components of the nervous system and cell membranes

Lipids forming the lipid bilayer

Phospholipids, sphingolipids, and cholesterol

Functions of depot fat

Stored energy, heat insulation, and protection of internal organs

Why lipids are efficient energy stores

Higher specific energy than glycogen or protein

Consequence of storing energy as glycogen instead of fat

Would require approximately doubling of body mass

Extracellular lipid signaling molecules

Steroid hormones synthesized from cholesterol

Eicosanoid origin and examples

Derived from C20 polyunsaturated fatty acids and include prostaglandins, thromboxanes, and leukotrienes

Intracellular lipid second messengers

Derived from breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2)

Main classification of lipids

Simple lipids and compound (conjugated) lipids

Definition of simple lipids

Esters of fatty acids with various alcohols

Types of simple lipids

Neutral fats and waxes

Definition of neutral fats

Esters of fatty acids with glycerol

Definition of waxes

Esters of fatty acids with alcohols other than glycerol

Definition of compound (conjugated) lipids

Esters of fatty acids with a non-lipid component

Types of compound lipids

Phospholipids, glycolipids, and lipoproteins

Composition of phospholipids

Lipids and phosphoric acid

Composition of glycolipids

Lipids and carbohydrates

Composition of lipoproteins

Lipids and proteins