Basic knowledge about hyperlipidemia: blood lipids, cholesterol, triglycerides and lipoproteins

**I. Basic Knowledge about Hyperlipidemia**

>

> 1. Blood lipids

>

Blood lipids refer to the total lipid components contained in the blood.

>

The main lipid components in blood are cholesterol, triglycerides, phospholipids, free fatty acids, and trace amounts.

Steroid hormones and fat-soluble vitamins (such as vitamin A, vitamin D, and vitamin E), etc.

They are normal components of blood and have important physiological functions.

>

> **2.** **How ​​is blood cholesterol metabolized?**

>

Except for brain tissue, all other tissues in the human body can synthesize cholesterol, with a daily synthesis of 1 to 2 grams.

The liver is the organ with the strongest synthetic capacity, accounting for more than three-quarters of the total synthetic output in the body. Secondly...

It's the small intestine. Cholesterol synthesis in the body is a complex process that requires the participation of many enzymes and energy.

>

Another source of cholesterol in the human body is the small amount ingested from food. In a normal person's diet...

Cholesterol mainly comes from animal-based foods such as egg yolks, animal organs, butter, and meat. Plant-based foods...

It contains no cholesterol; excessive consumption of plant-based foods can inhibit cholesterol absorption.

>

**3.** Is lower blood cholesterol always better?

>

Most (70%) of blood cholesterol is found in low-density lipoprotein (LDL) and is carried into tissue cells.

Further metabolism plays an important physiological role; therefore, lower cholesterol is not necessarily better.

>

Besides serving as a structural component of cells, cholesterol's main physiological functions include being converted into various forms of cholesterol in the body.

> Important steroid compounds, such as cortisol and aldosterone released by the human adrenal cortex, are sexually active.

The precursors to testosterone, estradiol, and vitamin D released by the glands are cholesterol. In the liver...

Some cholesterol is converted into bile acids, and bile plays an important role in the digestion and absorption of lipids.

>

Therefore, cholesterol is an essential substance indispensable for human life activities. Only when cholesterol...

Atherosclerosis is only induced when there is an excessively high level or an abnormal presence of low-density lipoprotein.

>

> 4. **What are triglycerides and what are their physiological functions?**

>

Triglycerides (TG), also known as triacylglycerols, are synthesized from one molecule of glycerol and three molecules of fatty acids.

> An organic substance, a major component of fat, and an energy storage substance in the body.

>

Like cholesterol, triglycerides also have two sources: one is exogenous, obtained from food.

In the small intestine, it is digested and absorbed, and then assembled with apolipoproteins synthesized by the small intestine itself into chylomicrons, which are then transported via the lymphatic system.

The system enters the bloodstream, and chylomicrons contain 90% triglycerides. Secondly, it is endogenous; the liver is responsible for synthesizing...

The liver is the organ with the strongest ability to synthesize triglycerides, followed by adipose tissue. The liver synthesizes triglycerides in conjunction with...

Lipoproteins assemble into very low-density lipoprotein (VLDL), which is secreted into the bloodstream. VLDL contains 60% VLDL.

> Triglycerides.

>

Triglycerides from chylomicrons and very low-density lipoproteins can release a significant amount of [something] as they pass through capillaries.

The body generates a large amount of energy, part of which is dissipated as heat and part is stored as adenosine triphosphate (ATP) to supply the body.

> The body's life activities require it.

>

> 5. **Lipoproteins**

>

Various lipid components, such as cholesterol, triglycerides, and phospholipids, are just like the oils we usually see.

These substances are insoluble in water and extremely difficult to dissolve in the blood; they must bind with a special protein (apolipoprotein).

> (white) combine to form a water-soluble complex, which is called a lipoprotein. These

Lipoprotein molecules, such as very low-density lipoprotein cholesterol (VLDL-C) and high-density lipoprotein cholesterol (HDL-C).

HDL-C and other substances have hydrophilic properties, dissolve in the blood, and enter tissue cells.

> As raw materials for building itself, nutrients.

>

> 6. **Classification of Lipoproteins**

>

Different lipoproteins are not entirely the same as proteins; scientists use methods such as ultracentrifugation or electrophoresis to differentiate them.

Analysis revealed that plasma lipoproteins were classified into five types: chylomicrons (CM), very low-density lipoprotein (VLDL), and so on.

> Intermediate density lipoprotein (IDL), low density lipoprotein (LDL), and high density lipoprotein (HDL).

>

The density of these five types of lipoproteins increases sequentially, while their particle size decreases sequentially. The key is these five...

Lipoproteins contain different amounts of cholesterol and triglycerides.

>

In recent years, a new lipoprotein named lipoprotein(a)[Lp(a)] has been discovered, with a density and

The particle diameter is between that of low-density lipoprotein and high-density lipoprotein, and its chemical structure is similar to that of low-density lipoprotein.

Similar to white blood cells, lipoprotein(a) has been found in epidemiological and clinical studies to be associated with coronary heart disease.

> Close contact.

>

**7.** How does high-density lipoprotein (HDL) function in human metabolism and physiological processes?

>

High-density lipoprotein (HDL), also known as alpha lipoprotein, is mainly composed of phospholipids and apolipoprotein A, containing only a small amount of other proteins.

> Amount of cholesterol.

>

High-density lipoprotein (HDL) is primarily synthesized in the liver and small intestine, but can also originate from chylomicrons and very low-density lipoprotein (VLDL).

The breakdown of lipoproteins. Newly formed high-density lipoprotein (HDL) enters the bloodstream and, due to its high density and large particle size, breaks down into smaller particles.

Small in size, it easily enters the interstitial space. Due to the effects of physical equilibrium, free cholesterol flowing out of cells easily...

It forms a complex with apolipoprotein A on high-density lipoprotein (HDL), while HDL also accepts lactose.

> Cholesterol and phospholipids transferred during the breakdown of microparticles and very low-density lipoproteins ultimately lead to the free cholesterol and phospholipids.

Cholesterol is esterified into cholesterol esters. High-density lipoprotein (HDL) continuously accepts cholesterol and is esterified into cholesterol esters.

Cholesterol esters. High-density lipoprotein (HDL) carrying cholesterol esters is eventually broken down in the liver, and its cholesterol is released with it.

> Bile is excreted from the body.

>

The main functions of high-density lipoprotein (HDL) are: ① to remove cholesterol from the body's cells and transport it to the liver.

> Decomposition; ② Competition with low-density lipoprotein (LDL), reducing the uptake of LDL by surrounding cells; ③

> Promotes triglyceride hydrolysis; ④ Inhibits cholesterol synthesis; ⑤ Inhibits smooth muscle cell proliferation and protects...

The endothelial cells are not damaged.

>

High-density lipoprotein (HDL) can transport intracellular cholesterol to the liver for metabolism and also clear [the liver].

It removes cholesterol from the arterial wall and can inhibit the uptake of low-density lipoprotein by the arterial wall, and is considered to be...

> A plasma lipoprotein that resists atherosclerosis and is a protective factor against coronary heart disease.