Blood lipids

Lipids are fat-like substances found in human blood and body tissues. Human body needs small amounts of lipids to work normally.

Cholesterol, triglycerides, and high-density lipoproteins are important constituents of the blood lipids fraction of the human body.

Cholesterol is an unsaturated alcohol of the steroid family of compounds; it is essential for the normal function of all animal cells and is a fundamental element of their cell membranes. Cholesterol is a fatty substance produced by the liver and carried by the blood to supply material for cell walls and hormones. It is also a precursor of various critical substances such as adrenal and gonadal steroid hormones and bile acids.

Cholesterol is a type of fat, and fats can’t travel in the blood on their own. They need to be attached to proteins. Lipoproteins are little parcels made of fats and proteins that carry fats around the body. Lipid is another name for fat, so ‘lipoprotein’ means fat plus protein.

In the human bloodstream, triglycerides play an important role in metabolism as an energy source and in helping to transfer dietary fat throughout the body. They contain more than twice as much energy as carbohydrates, the other major source of energy in the diet.

When eating, human body converts any calories it does not need to use right away into triglycerides, which are stored in body fat cells. When body need energy between meals, hormones trigger the release of some of these stored triglycerides back into the bloodstream.
Blood lipids

What are lipids?

Lipids are organic compounds that contain hydrocarbons which are the foundation for the structure and function of living cells.

Lipid molecules contain large hydrocarbon portion and not many polar functional group, which accounts for their solubility behavior. Their intermolecular interactions are dominated by the hydrophobic effect and van der Waals interactions.

Lipids are water insoluble organic compounds. They are hydrophobic (nonpolar) or amphipathic (containing both nonpolar and polar regions)
*Free fatty acids
*Triacylglycerols
*Phospholipids
*Glycolipids
*Steroids

Fatty acids are “carboxylic acids (or organic acid), often with a long aliphatic tails (long chains), either saturated or unsaturated.” When a fatty acid is saturated it is an indication that there are no carbon-carbon double bonds and if the fatty acid is saturated it is an indication that it has at least one carbon-carbon double bond.

Lipids are major components of cell membranes, and are responsible for most of the permeability filter functions of membranes. Membranes act as barriers to separate compartments within eukaryotic cells, and to separate all cells from their surroundings.

A lipid abnormality is one of the causal factors of cardiovascular disease. Excess LDL cholesterol (say a total serum cholesterol > 4-5mmol/L) is the most widely accepted risk factor for heart disease. Excess triglycerides (say >1.8mmol/L) are probably important in CHD but this is controversial. A low concentration of HDL cholesterol (say less than 1.0mmol/L) is also accepted as a major risk factor.
What are lipids?