Cholesterol is biosynthesized within our bodies. It is a waxy substance and not necessarily a bad one.
Cholesterol is needed in the body to build up the cells, process other essential elements like steroid hormones and fat-soluble vitamins.
Types Of Cholesterol And Cholesterol Synthesis Within The Body
It can pose a threat to our health if its level shoots above the normal one for an individual.
Cholesterol in our system comes from two sources, a portion of it is synthesized within our liver and the rest comes from external food sources.
80% of the total cholesterol requirement of our body is met by manufacturing it in the liver.
A small amount of cholesterol is also synthesized within the intestine, reproductive organs, adrenaline glands, and brain.
The cholesterol synthesis in the liver occurs on the cytoplasm with the help of certain enzymes present within the cytoplasm and the smooth endoplasmic reticulum.
The first step in the synthesis of cholesterol is marked by the condensation of two molecules of Acetyl Co-enzyme A (CoA). This step results in the formation of two molecules of acetoacetyl CoA.
Next, the enzyme HMG CoA synthase adds a third molecule of acetyl CoA to acetoacetyl CoA, producing a six-carbon compound called 3-Hydroxy-3-Methyl glutaryl coenzyme A (HMG CoA).
HMG CoA catalyzes the reaction ketogenesis to reduce the compound to mevalonate.
The production of mevalonate is the key step in the synthesis of cholesterol.
Mevalonate then passes through a series of reactions to finally produce cholesterol as the end product in the endoplasmic reticulum of the liver.
Anatomy of the liver:
Since the liver is the principal site of cholesterol synthesis within the body, it is crucial to understand the anatomy of the liver.
The liver is conical in shape and dark reddish-brown in color and weighing roughly 3 pounds.
The blood source of the liver is the circulation carried out by the hepatic artery and the blood carrying nutrients reaching the liver through the hepatic portal vein.
13% of the body’s blood supply is held with the liver at any given point in time.
The liver can be segmented into two main lobes, each of which is made up of 8 segments containing 1000 ducts.
These are connected to smaller ducts that, in turn, combine to form the common hepatic ducts.
This common hepatic duct is responsible for the transportation of bile produced in the liver to the gall bladder and the duodenum through the common bile duct.
Main functions of the liver:
Other than the production of cholesterol, the liver is known to possess more than 500 vital functions in the body.
These functions include but are not limited to the production of bile that is associated with the digestion of fat, production of proteins for the blood plasma.
It regulates the level of amino acid in the blood that is essential for the manufacture of protein within the body.
Liver also carries out filtering out the blood for the elimination of toxic products in the body, and the conversion of harmful ammonia into urea, which is later excreted through urine.
The liver stores iron in the body, so it also processes the hemoglobin for utilization of the iron content.
Regulating the process of blood clotting and countering infections by monitoring the immunity of the body and removing the bacteria from the system is also done by the liver.
The liver also plays a role in clearing out bilirubin from the hemoglobin. Accumulation of excess bilirubin in the bloodstream results in yellowing of skin and eyes.
As the liver breaks down the harmful substance in the body, bile is produced hat is later excreted through feces and the harmful urea is excreted through urine, thus keeping the body toxicity free.
Classification of cholesterol:
Cholesterol is classified into three categories as, total cholesterol, Low-Density Lipoprotein (LDL) or bad cholesterol, and High-Density Lipoprotein (HDL) or good cholesterol.
High levels of total cholesterol and LDL in blood I harmful for health and poses some serious threat like heart attack and stroke.
HDL is usually good for health and provides protection against many cardiovascular conditions.
Importance of cholesterol for the body.
Cholesterol is important for the vital functions of the body; these include building the structure of the cell membranes, production of hormones like estrogen, testosterone, and adrenaline.
Cholesterol helps in maintain an efficient metabolism system. It is needed by the body for the production of vitamin D.
Furthermore, cholesterol aids in the production of bile acids that regulates the digestion of fat and the effective absorption of vital nutrients.