Chemical reactions in the body

The Chemical Reaction Between “Assimilation” and “Alienation”

　　Academician Liu Sizhi, a famous Chinese biochemist, explained the chemical reactions in the body in this way: the living is transformed, and the chemical is regenerated, and the biochemical is the metabolized;
　　The normal functioning of the body depends on our constant interaction with external substances, whether it is ingesting food or breathing air, but the question is, how do external substances work in the body? Chemistry provides a good entry point, “transformation” means “transformation”, so “chemistry” is the knowledge of transformation. Substances that do not belong to the human body are transformed into a part of the body or become nutrients that the body needs (“living, transformation and rebirth”). This process is called assimilation; after “transforming” into a body part, when needed, this part will Alienation occurs, and alienation is the consumption of a part of the body, allowing it to perform different physiological functions, and the residues produced are excreted from the body (“New must be Chen, Chen Naixie”).

protein breakdown and synthesis
The past and present of protein

　　The relationship between feeding and assimilation is the easiest to understand. Let’s take protein foods (meat, milk, eggs) as an example. After they are eaten, they will first be hydrolyzed by gastric acid and small intestinal fluid. The essence of this process is the chemical decomposition reaction of protein catalyzed by digestive enzymes. Only when they are disassembled into amino acids can they be absorbed by the human body; and the absorbed amino acids are brought to specific parts by the blood, and this time they will be synthesized into functional proteins of the human body under the action of biological enzymes.
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protein family

　　Protein is an important component of all cells and tissues in the human body, and the normal operation of various life activities in the human body is inseparable from protein. Next, let us briefly understand several proteins in the human body. Albumin, which is one of the important energy-supply substances, is of great significance to maintaining a stable environment in the body; gamma globulin (referred to as “gamma globulin”), which plays a vital immune role when the human body is infected; A coagulation factor (protein), which plays a key role in hemostasis; and various digestive enzymes, which we cannot do without to obtain various nutrients from food.

transport of oxygen
A “transfer” journey about oxygen

　　Another typical assimilative phenomenon of the body is breathing. Hemoglobin is the result of chemical synthesis of amino acids in the bone marrow. Red blood cells “assemble” hemoglobin and enter the blood circulation. When flowing through the alveoli, the hemoglobin will react with the inhaled oxygen for oxygenation. This process is fast and powerful, and it all depends on the ability of Fe2+ in hemoglobin to accurately “hook oxygen”. What’s even more amazing is that oxygen and Fe2+ will be quickly decoupled in the oxygen-requiring parts of the human body. This rapid dissociation reaction is the basis for the smooth use of oxygen by the human body.
　　The use of oxygen by the human body is also reflected in the dissimilation. The most common is that the body consumes glucose to produce energy, which is the most important form of metabolism for maintaining vitality. After carbohydrates are ingested, they will be assimilated into liver glycogen for storage. When energy is needed, glycogen will be decomposed into glucose. The process of complete oxidation of glucose will release heat, which can support various life activities, and at the same time generate carbon dioxide (CO2) and water, are excreted from the body. Glycogen in muscles is also broken down during malnutrition, so weight loss during malnutrition can also be seen as the result of chemical reactions.
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Interpretation of CO poisoning from a chemical point of view

　　Compared with oxygen, the “iron hook” of hemoglobin is more “friendly” (chemical term, higher affinity) to gas (the main component is carbon monoxide [CO]). Therefore, the core coping mechanism in the clinical treatment of gas poisoning patients is such a simple chemical reaction. So, what do you think is a good way to treat gas poisoners? The answer is to inhale hyperbaric oxygen. High pressure makes the combination of oxygen and hemoglobin stronger, which can competitively inhibit the effect of CO.

Decomposition and absorption of glucose
Cellular “Absorption” – Establishment of Chemical Equilibrium

　　How are minerals and water absorbed by our body? To understand how they are absorbed by the gut, we need to understand the “balance” of the chemical formula. Although “balancing” is just a mathematical technique, the underlying logic is very profound, that is, the conservation of matter – when a chemical reaction occurs, the atoms and electrons on both sides of the chemical equation flow dynamically, and the forward and reverse reactions tend to “balance”.
　　Let’s go back to the intestinal tract, where the concentration of minerals is much higher than that in the cells of the intestinal wall. At this time, some substances in the minerals diffuse from the side with high concentration through the cell membrane to the cells with low concentration. This process is called It is called “free diffusion”, which is actually the process of establishing chemical equilibrium. Positive ions (typically H+, Na+, Ca2+, etc.) and negative ions (typically OH- and Cl-) at both ends of the equation are dynamically exchanged. In the process of gradually approaching equilibrium, the substances needed by the human body are absorbed by cells (such as Na+, Ca2+, etc.), harmful substances (such as NH4+) are discharged into the large intestine by cells.
　　In addition, there is another kind of absorption, the process of which is more complicated. It does not depend on the concentration of substances in the intestines, but uses the specific channel openings on the cells to accurately absorb the ingredients needed by the human body. This process is called “active transport”, which requires energy consumption and is a chemical transport process inverse concentration.
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chemical bond

　　Chemical bond is a general term for the strong interaction force between two or more adjacent atoms (or ions) in a molecule of a pure substance or in a crystal. Covalent bond is a kind of chemical bond. Two or more atoms use their outer electrons together, and ideally reach electron saturation, thus forming a relatively stable chemical structure. The external forces that rely on the combination of atoms other than covalent bonds are called non-covalent bonds, including ionic bonds, metal bonds, and intermolecular forces. Compared with covalent bonds, their chemical structures are more flexible.
“Regulatory” role of hormones

　　Hormones are chemical substances synthesized in the human body that have specific effects. For hormones to function, they depend on specific target cells and activate their effects, which is essentially a chemical process at the microscopic level.
　　The protein or sugar structure distributed on the surface of effector cells is specific, which means that only specific molecules can be “recognized”. They are called “receptors”, and the corresponding molecular signals are “ligands”. Hormones are typically molecular signals that bind to receptors when they come into contact with effector cells. More precisely, in chemical terms, the two will be combined in the form of non-covalent bonds. This combination itself is a signal for intracellular effects, aiming to initiate regulation at the gene level in the cell, and it appears as a signal on the macroscopic level. Respond, produce effect.

Free Diffusion and Active Transport

　　In other words, rather than saying that hormones are performing a certain physiological function, it is better to think that the key of hormones opens the door for cells to exert their effects (as shown in the figure below).
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Chemical reactions of bacteria in the body

　　Chemical reactions in the body are not unique to the human body, and the bacteria in the gut also participate in it. Certain proteins that cannot be fully digested can be metabolized by bacteria, a chemical reaction known as putrefaction. Most of the products of corruption are unfriendly to the human body and are often excreted by the intestines, especially hydrogen sulfide, which is very smelly. The chemical reactions in the body in which bacteria are the protagonists are not alienation, they are just the result of the bacteria’s own metabolism.
　　The normal operation of the human body involves chemical reactions. In addition to the ones mentioned in this article, there are many interesting chemical reactions in the human body, waiting for us to continue to explore.