Expand one's knowledge
Lipid is one of the important nutrients needed by human body, which provides energy and essential fatty acids for human body and is a component of human cell tissue. The human body needs to consume a certain amount of lipid substances every day, but excessive intake will lead to the occurrence and development of diseases such as hyperlipidemia and atherosclerosis.
function
1, energy storage is the best way to store energy, such as animal triglycerides and oil. By comparing the following data, it can be concluded that the storage volume is 1 glycogen or starch: 2 water, while the fat is pure and much smaller. In the order of utilization: sugar is consumed first, and then lipid is consumed. So many weight loss/slimming principles, such as breaking the valley, all come from this.
2. Biofilm skeleton: liquid mosaic model of cell membrane: phospholipid diester layer, cholesterol, protein, glycolipid, glycerophosphate and sphingomyelin.
3. Electrical and thermal insulators: Animal adipose tissue has protective functions such as heat preservation and mechanical stress prevention, and plant wax can prevent water from evaporating. Electrical insulation: sheath cells of nerve cells, sheath of electric wires, and short circuit of nerves. Insulation: keep warm in winter, penguins, polar bears, etc.
enzyme hydrolysis
1, lipase widely exists in animals, plants and microorganisms. In human body, fat is digested mainly in the small intestine, catalyzed by pancreatic lipase, and gradually hydrolyzed into fatty acids and glycerol with the help of bile salts and paralipases.
2. There are many kinds of phospholipases, which act on ester bonds in different parts of phospholipid molecules. Phospholipase A 1 and A2 act on the ester bonds of 1 and 2, respectively, producing lysophospholipids and free fatty acids. The enzyme acting on the 3-position is called phospholipase C, the enzyme acting on the ester bond between phosphate substituents is called phospholipase D, and the enzyme acting on the lysophospholipid 1 ester bond is called phospholipase B 1.
3. Cholesterol esterase hydrolyzes cholesterol esters to produce cholesterol and fatty acids.
4. The small intestine can absorb the hydrolysate of lipids. Bile salts help emulsification, combine with apolipoprotein to form chylomicrons, which are absorbed by intestinal mucosal cells and enter the blood circulation. Chyloid microparticles are lipoproteins that transport exogenous lipids.