CHOLESTEROL

Origin It is composed of 2 Greek words: Chole= bile. Steros= solid. It was first discovered ,in solid state as a compound in a gallstone, by a French doctor called Francois Poulletier de La Salle

Importance of Cholesterol It is important for the formation of cell membrane: It regulates its fluidity. It regulates its relative permeability to hydrophilic substances.

Importance of Cholesterol Main component in the synthesis of steroid hormones such as oestrogen and testosterone. It is deposit in the skin which makes our skin water proof. Vitamin D in made from cholesterol, in skin cells stimulated by ultraviolet light. Used for making bile.

Cholesterol story Cholesterol is present in the diet, especially in meat, egg and dairy products. It is absorbed in the small intestine. The cholesterol in dairy product reduces the activity of one of the enzymes that catalyses the synthesis of cholesterol from acetyl coenzymeA in the liver. Large quantities of saturated fats in diet cause the liver to increase the rate of the enzyme.

Transportation of cholesterol in the blood Cholesterol is not water soluble(hydrophobic). It is transported in blood plasma as lipoprotein.

Lipoprotein in blood Low density lipoprotein (LDL): High density lipoprotein (HDL): Deposits as plaques on the blood vessel wall. Protect against plaques. May even remove plaques. A high ration of HDLs to LDLs can reduces the risk of cardiovascular diseases.

Risks of cholesterol Cardiovascular diseases, like strokes and heart failure. Gallstones in the gall bladder. Plaques in blood vessels which causes hypertension

Factors affecting the cholesterol level You should avoid: You should do: Fast food and junk food. Excess of saturated fats in diet. Smoking , smoking and smoking. Increase the uptake of unsaturated fats in diet. Sports and activities.

References Made by Aya Ihab Rezeika. E-mail: ayaihab@hotmail.com Cambridge advanced sciences- Mammalian physiology and behavior. by Mary Jones Geoff Jones Images : yahoo search