BIOCHEMISTRY II

Submitted To: Submitted By:Sir Mubin Mustafa Mehrwar Hijab

CLINICAL IMPORTANCE OF

CHOLESTEROL

WHAT IS CHOLESTEROL?

Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals.

It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and fluidity.

Cholesterol is the principal sterol synthesized by animals, but small quantities are synthesized in other eukaryotes, such as plants and fungi. It is almost completely absent among prokaryotes.

Cholesterol is classified as a sterol (a contraction of steroid and alcohol).

 WHERE DOES IT COME FROM?

Most of the cholesterol in the body is synthesized therein; some is absorbed in the diet

Cholesterol is primarily synthesized from acetyl CoA through the HMG-CoA reductase pathway in many cells and tissues. About 20–25% of total daily production (~1 g/day) occurs in the liver; other sites of high synthesis rates include the intestines, adrenal glands, and reproductive organs.

Major dietary sources of cholesterol include cheese, egg yolks, beef, pork, poultry, and shrimp. 

FUNCTIONS

Cholesterol performs three main functions: It helps make the outer coating of cells. It makes up the bile acids that work to digest food

in the intestine. It allows the body to make Vitamin D and

hormones, like estrogen in women and testosterone in men.

Without cholesterol, none of these functions would take place, and without these functions, human beings wouldn't exist.

OTHER FUNCTIONS

It is an important component of cell membranes. In the central nervous system it exerts an insulating

effect due to its high dielectric constant. Being an alcohol, cholesterol forms esters with fatty

acids for which it acts as a special transport. Cholesterol is a constituent of plasma lipoproteins,

the richest being LDL.

IMPORTANCE IN OUR BODY Cholesterol is an important component of the cell

membranes, including organelle membranes inside the cell. (The body contains billions of cells.)

The right proportion of phospholipids, fatty acids and cholesterol in cell membranes allows them to be flexible while still holding their shape.

“Cholesterol is used by the body as raw material for the healing process. This is the reason the injured areas in the arteries (as in atherosclerosis)… have cholesterol along with several other components (such as calcium and collagen) in the “scar” tissue that is formed to heal the “wound”.

Cholesterol is found in large amounts in brain tissue where it is needed for normal brain function. Research has shown that cholesterol in eggs is helpful to older people whose memory is declining.

CONT… Cholesterol often elevates as part of a protective immune system

response to chronic infection.

Infants need plenty of cholesterol for proper brain development and cholesterol is normally found in large amounts in human breast milk. (Infant formulas usually contain little to no cholesterol because of the widespread lack of understanding about cholesterol.)

Adrenal and gonadal hormones are made from cholesterol. These are the stress handling, energy producing and reproductive hormones. (This is why serum cholesterol normally elevates with excessive or prolonged stress.)

Cholesterol is vital for proper nerve function. Three quarters of the myelin membrane is made from fat and of that nearly one quarter is cholesterol.

CONT…

Vitamin D is made from cholesterol in the skin.

Cholesterol is converted into bile salts in the liver which are needed to break down and emulsify fats.

Cholesterol is needed in large amounts in the skin where it is vital for skin health and strength.

Although lowering serum cholesterol does seem to decrease deaths from heart disease, it “does not, in the least, improve overall mortality rates. People who achieved the lowest cholesterol levels – 160 units or less – had unexpectedly higher rates of death from other causes, such as liver cancer, stroke, lung disease, alcoholism and suicide

WHEN GOOD FATS GO BAD When there's too much cholesterol in the blood, it collects

on the inside linings of blood vessels, similar to the way grease and fats poured down the sink collect inside drain pipes. When plaques of cholesterol form inside arteries, it's known as atherosclerosis or "hardening of the arteries," which can lead to strokes and heart disease.

The main culprit in this dangerous process is cholesterol that's packaged into lipoproteins that are less dense with protein and have more fats. These low-density lipoproteins, are the "bad" cholesterol that collects in plaques on artery walls.

There's a hero in this tale, though -- and it's also cholesterol. More specifically, cholesterol that's packaged by the liver into lipoproteins that are dense with proteins and have less fat. These high-density lipoproteins, or HDL, are the "good" cholesterol. What's good about HDL is the way it seems to remove plaques of LDL inside arteries, "cleaning" the arteries as it moves through the bloodstream.

IN SHORT….

Cholesterol is vital to the healthy function of your body, actually core to survival.  You want good levels of HDL and LDL because you are healthy, not because you have drugged them to look better on paper.  The idea of cholesterol fitness, like physical fitness, is a proper way to look at this issue.

THANK YOU !