Lipids are chemical compounds belonging to a very heterogeneous group of organic molecules essential for life: they are biomolecules.. They are compounds of a hydrophobic nature, which means that they are insoluble in water but soluble in organic solvents such as alcohol or ether. Lipids play fundamental roles in the body, be it as a source of energy, structural components of cells, or as chemical messengers.
In this article, we will explore in detail what lipids are, their functions in the human body, and the different types of lipids that exist. Below we offer you the opportunity to better understand what are lipids Fundamentals, functions and types.
What are lipids?
Lipids are organic macromolecules composed mainly of carbon, hydrogen, and oxygen, although they may also contain phosphorus, nitrogen and other elements. They constitute one of the four essential biomolecules of life: carbohydrates (also called carbohydrates or carbohydrates), lipids, proteins and nucleic acids. On these molecules is built all life as we know it.
The main characteristic of lipids is their insolubility in water due to its nonpolar or hydrophobic chemical structure. Lipids are essential biological molecules found in all living cells and perform a wide variety of biological functions that we will detail below.
lipid functions
As we have mentioned, lipids are a very heterogeneous group of molecules from a chemical point of view and very versatile from a functional point of view. Look at the important roles that this particular group of essential biomolecules play in the body.
Energy storage
Due to their chemical structure, lipids are compounds capable of storing a large amount of energy in their bonds. It is because of that They are the molecules par excellence destined to store energy in the organism. So much so, that one gram of lipids contains approximately twice the amount of energy than one gram of carbohydrates or protein.
Lipids stored as triglycerides in adipose tissue and are used as a power source when needed. In addition, the storage of lipids in the body provides thermal insulation and protection against mechanical impacts. To learn more about how irregularities in lipid metabolism can affect cats, you can read about feline hepatic lipidosis.
structural components
Lipids too are essential components of cell membranes. The phospholipids form a lipid bilayer that makes up the main structure of cell membranes (described through the model of fluid mosaic), providing an impermeable barrier and regulating the passage of substances in and out of the cell.
Furthermore, lipids are present in tissues such as skin and hair, providing integrity and flexibility in structures that are essential for survival. For a deeper understanding of food classification, which also covers lipids, see our guide on food classification.
isolation and protection
Some lipids, such as DEPILATORY and subcutaneous fats, help to insulate and protect the body's organs. they act as one insulating layer to maintain body temperature and protect internal organs from possible damage. For example, the visceral fat that surrounds the abdominal organs helps protect them from shock and provides structural support. The lipids together with the connective tissue act as support for the viscera in the peritoneal cavity (the space that houses them).
transport of substances
Lipids also play a crucial role in transporting substances in the body. lipids known as lipoproteins they transport water-insoluble lipids, such as cholesterol, through the bloodstream to the tissues where they are required. Lipoproteins are composed of an outer layer of lipids and a core protein, and are classified according to their density: chylomicrons (the largest and least dense lipoproteins), very low density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL). For more information about organisms that depend on these biomolecules, you can see the examples of heterotrophs.
Hormones and chemical messengers
Some lipids act like hormones or chemical messengers in the body.. For example, steroid hormones, such as glucocorticoids and sex steroids (sex hormones), are lipids that regulate various bodily functions, including metabolism, sexual development, and the immune response. Also, lipids called eicosanoids, As the prostaglandins (hormone associated with pain and inflammation) and leukotrienes, play a role in the regulation of inflammation and the immune response.
Lipid Types
There are several types of lipids, each with unique characteristics and functions that, as we have been advancing in these lines, have already been mentioned since structure and function form an inseparable binomial, and the mention of one necessarily entails the mention of the other.
Triglycerides
They are the most common type of lipid and are made up of oils and fats. They are composed of a glycerol molecule and three fatty acids. Triglycerides are a form of energy storage in the body and are broken down during digestion to release energy. They also provide thermal insulation and protection to internal organs.
Phospholipids
essential components of cell membranes. They are made up of a glycerol molecule, two fatty acids and a phosphate group. The structure of phospholipids allows the formation of a lipid bilayer, which is impermeable to water and helps maintain cell integrity. Phospholipids also have a hydrophilic part (glycerin and phosphate with their radicals, if any) and a hydrophobic part (hydrocarbon chains of fatty acids), which allows them to interact with polar and water-insoluble substances.
Steroids
They are structural lipids that include steroid hormones and cholesterol. Steroids play an important role in the metabolism regulation, sexual development and the immune response. Cholesterol is a key component of cell membranes, giving them rigidity, and is also used by the body to produce steroid hormones, vitamin D y bile acids.
Wax
They are lipids that are solid at room temperature and resistant to water that are found in the leather, feathers and plant leaves. The waxes act as protective barrier against water loss and the entry of unwanted substances. They also provide an outer shell resistant to physical damage and protect against dehydration in terrestrial organisms and plants.
Lipoproteins
They are lipid-protein complexes that transport water-insoluble lipids through the bloodstream (such as cholesterol). We anticipated previous paragraphs that lipoproteins are classified according to their density, in such a way that we found four types: chylomicrons, VLDL, LDL y HDL. LDL transports cholesterol from the liver to peripheral tissues (popularly known as “bad cholesterol”), while HDL collects excess cholesterol and returns it to the liver for elimination (misdesignated as “good cholesterol”).
Busting myths: There is no good or bad cholesterol
Note that there is no such thing as good or bad cholesterol. The cholesterol molecule is a single molecule with a well-defined composition. The terms "good" or "bad" are a popular allusion to two metabolic situations that are desirable (healthy) or not so desirable (unhealthy): when there is excess cholesterol in the blood, it is transported by LDL lipoproteins ("bad cholesterol"), and when cholesterol levels are balanced, it is transported by HDL ("good cholesterol"). In reality, what changes in each situation is the type of lipoprotein that transports the cholesterol, not the cholesterol itself, of which there is only one type.
Beyond its essential nature: applications in the food, pharmaceutical and cosmetic industries
Lipids are essential molecules for life and perform a wide variety of functions in the body. Understanding the importance of lipids helps us appreciate their crucial role in health and the functioning of the human body and life in general (in plants and bacteria they are also essential). Besides, lipids also have applications in the food, pharmaceutical and cosmetic industries, which highlights its relevance in different fields.
Various investigations are constantly underway to improve cosmetic products (which move a large amount of money) and the cure of diseases. Literally without lipids (or the rest of the essential biomolecules) life would not be possible, so it is vitally important to know what lipids are: fundamentals, functions and types.