Material in the chemical process and the physiologically relevant in vivo digestion, absorption, translocation, decomposition called metabolism. Metabolism of both Assimilation
And Alienation effect
Material metabolism Characteristic
(1) in various metabolic activities are linked to form a whole;
(2) metabolism continues to receive fine adjustment;
(3) of each tissue and organ metabolism characteristics;
(4) the metabolites have common metabolic pool;
(5) ATP is the body's energy storage and energy consumption of the common form;
(6) NADPH provides reducing equivalents required anabolism.
Material metabolism Difference
Human and animal from the external environment in the food intake of both animal and plant, but the main ingredient is nothing more than carbohydrate, fat and protein of the three major nutrients. These substances in the digestive system of domestic demand by decomposition of a series of digestive enzymes, organic matter becomes relatively simple, can be absorbed by the small intestine. Such as starch or sucrose is broken down into simple sugars, protein breaks down into amino acids, fat is decomposed into glycerol and fatty acids. These small organic molecules is absorbed into the blood, constitute a part of the human body, and participate in a variety of metabolic link.
Material metabolism Detailed
Material metabolism Assimilation
Metabolism is the basic feature of life. From life Unicellular
To the complex body, and all around
Exit to material exchange, the exchange of material called metabolism or The new supersedes the old. Metabolism including Assimilation
The metabolic changes and dissimilation in two different directions. Biological activities in life constantly from the environment intake Nutrients
And into the body composition, called assimilation; at the same time the body itself has been decomposed into material metabolites excreted, called dissimilation.
Material metabolism Alienation effect
The metabolism process is very complicated, even in metabolism within a cell, also contains a series of interrelated synthesis and decomposition of chemical reaction. Generally speaking by small molecule synthetic macromolecules reactions Synthesis and metabolism
If, by Amino acid
Synthesis of macromolecular protein reaction; by macromolecular substance decomposed into small molecule reactions Catabolism
, such as large molecules into small molecules of glucose glycogen decomposition reaction. Metabolism is often accompanied by Energy conversion
Often, catabolism of energy release, synthesis and metabolism often absorb energy, decomposition need to release energy available for anabolic metabolism.
Material metabolism Three stages
Metabolism can be divided into three stages:
Material metabolism Digestion and absorption
The digestion and absorption. The nutritional content of food, in addition to water
, inorganic salts, vitamins and Monosaccharide
Other small molecules can be directly absorbed by the body, polysaccharide, protein, lipid and nucleic acid had to be digested, broken down into simpler water soluble substances can be absorbed into the body. The food in the digestive tract after enzyme catalyzed hydrolysis
Called a variety of digestion; Nutrients
The digestion products, water, vitamins and inorganic salts, the intestinal mucosal cells into Small intestinal villi
The capillaries and Lymph gland
The process is called absorption.
Material metabolism Intermediate metabolism
The intermediate metabolism. The food was digested, the blood and lymph fluid transported to various tissues in metabolism, with each other in many enzymes catalyzed decomposition and synthesis of cell metabolism, inside and outside The exchange of material
And the energy change.
Material metabolism excretion
. The material to produce a variety of end products through the metabolic process, the end product of the kidney, intestine, liver and lungs with urine and feces, bile
Exhale and excreted etc..
Material metabolism General chemical change
Metabolism also known collectively in various organisms The new supersedes the old., chemical changes, including changes in the body of the Assimilation
Chemical changes, including chemical changes in the role of alienation, assimilation means Synthesis and metabolism
But, dissimilation means Catabolism
. Synthesis is the synthesis from food to the body or the original small molecules as molecular body structure and function, the general number of macromolecular compounds; for example, Amino acid
In the available energy under the condition of condensation into protein molecules. Product metabolism always some small molecules, such as glycogen degradation of large molecules into glucose and glucose was decomposed into carbon dioxide, energy and stored temporarily in the high-energy phosphate bond in ATP, for the synthesis and metabolism of various physiological activities of. Whether it is anabolic or catabolic, is not a simple process, need to complete gradually through a series of chemical reactions, and the chemical reaction is mild in vivo environment, catalyzed by enzymes, were at a high speed.
Material metabolism The final product
A series of chemical reactions that are connected together, is called The metabolic pathway
. In short, the material metabolism is organism during its lifetime, obtaining material from its surroundings, in vivo through various metabolic pathways, and finally converted to the final product, process and return to the environment.
Material metabolism research method
Material metabolism channel
Methods the metabolism of more than one kind of chemical reaction, and in many ways is more and more complex, and are all in the same tiny cells at the same time, it is difficult to study. With the development of research methods, now some understanding of the body has many important metabolic pathways.
Material metabolism Balance experiment
Feeding experiment 1: complete balance of animal excretion determination of a substance in food intake and food itself or its metabolites, and used to infer its metabolism in vivo. Nitrogen balance experiment is an example, although not all measured chemical reaction protein through metabolic pathways in vivo, but can determine the utilization rate, demand and physiological value. The feeding balance test of that other substances, such as inorganic salts, is it necessary and demand is undoubtedly useful. In addition, a complete animal feeding experiment, a variety of vitamins, have made certain contribution. Some vitamins are indispensable substance metabolism.
Material metabolism Organ perfusion method
2 organ perfusion method: a material into an organ in the blood, and then analysis the substance in the blood outflow organ derivative
When, can be informed of the substance metabolism changes in this organ. For example, research Amino acid
Changes in the liver, the amino acid injection after portal vein, hepatic vein blood analysis of amino acid derivatives, amino acids can be found by oxidative deamination and become alpha keto acid, and release ammonia
At the same time, we can also see the urea concentration in the outflow of hepatic blood than in high. It can be proved that the deamination of amino acids is in the liver, and to remove ammonia urea transformation in the liver. The advantage of this method is that the perfusion of the organ has not been separated from the whole animal, all the physiological conditions are normal, especially the control of neural and hormonal regulation are still basically the same with normal animal. Perfusion method is also applied to isolated organs, such as liver, heart
So, that is the study material more easy identification and determination of derivatives. At the organ level, but also can be used to determine the removal of organs of a substance in a metabolic organ; if the protein removal of the liver when feeding animal, can be found in the blood Amino acid
And ammonia (from intestinal absorption) concentrations were significantly increased, while urea content is a large decline. This will undoubtedly prove organ perfusion experiment results that amino acid oxidation deamination and urea synthesis to remove ammonia toxicity in the liver in the liver.
Material metabolism Tissue slice method
3 tissue slice method to measure the metabolic pathway of a substance is more convenient and accurate for organ tissue slice. This method is completely reliable control and control. Both liver and kidney, brain and other tissues cut into about 50 m slices, the contact surface with full bath, let Nutrients
Exchange and metabolic products suitable to maintain cell viability in tissue for hours. A certain amount of research material is mixed in a bath in the heat, after a certain time, the determination of various substances in the bath of metabolic pathways, can be concluded that the conjecture or research material for example, will be mixed with ammonium salt bath and heat and liver slices, a few hours later, ammonium salt decrease of urea appeared. The results show that ammonia into urea in the liver transfer.
Material metabolism Subcellular level method
4 method: to determine the subcellular level to carry out chemical reactions within the cell site, can be organized in the Homogenizer
In grinding homogenate, cell rupture. Then by differential centrifugation, various subcellular fractions can be obtained, such as the nucleus, Mitochondrion
and plasma membrane
The body generally refers to the rough and smooth endoplasmic reticulum and Golgi apparatus fragments; from rough endoplasmic reticulum, also isolated ribosomes. These are different subcellular structures. Respectively with different subcellular structures for experiments can prove this point. For example, mitochondria may prove biological oxidation sites, Three carboxy cycle
So, in the beta oxidation, the generated energy stored in ATP, and physical activity with. As another example, ribosomes on the rough endoplasmic reticulum has proved to be the site of protein synthesis, and protein synthesis, the endoplasmic reticulum and transported to the Golgi apparatus
In the process, and after the transformation, then to extracellular secretion. Again, the nucleus has been confirmed for the synthesis of various RNA. Method using subcellular structures, not only on the metabolic pathways, positioning, but also promote the metabolic pathways of details.
Material metabolism Application of pure enzyme
Application of 5 pure enzyme from various methods to complete animal development level of subcellular structures, various enzymes are mixed with each other, but also did not separate from the organism composition of various composition. The completely understanding the details of chemical reactions is extremely difficult. The use of pure enzyme can not only know the exact reaction catalyzed by it, but also its detailed study to promote all aspects of the reaction. Many will be promoted by the pure enzyme reaction in turn together on some of the metabolic pathways of important substances, whether it is the synthesis of or decomposition, can generally understand. This is true. Now, carbohydrates, lipids, nucleic acid protein, Biological oxidation
Well, some biological active substances in the transformation pathway in vivo, have certain understanding.
In addition, in the study of metabolic pathways in microorganisms are often used. Can be seen from the above description, in the study of metabolism, the use of materials, is a complete animal gradually developed into the pure enzyme. This development process, is the development of modern science and technology and instrument results. The development of modern technology and equipment can not only locate, separate
Tracking and identification and Determination metabolite
And its products, but also to study the metabolism of biological molecules in the composition, structure, configuration, conformation and properties, and the results are likely to explain or determine its function in metabolism.
Material metabolism The metabolic pathway
along with research method
The development way of metabolism gradually for people to understand.
The organism from the environment intake Nutrient
, sugar, lipid, protein and nucleic acid is the most. After entering the body, into the metabolic pathway. A metabolic pathway is composed of many chemical reactions in regular sequence occurred one after another and completed most of the reaction are temperature, pH and ion concentration in mild conditions, by promoting enzyme, with very high speed. Each enzymatic reaction almost is catalyzed by a specific enzyme, and many enzymes and its essential cofactor. For example, into the body of nutrients, "a" in the metabolic pathway, will be transformed into the intermediate "B, C and d..." Until the final product "Gui", can be illustrated as follows:
1 enzyme enzyme 2 enzyme 3
A, B, C - - - - ding...... Decyl
The 1 auxiliary auxiliary auxiliary 3 2
In 1, 2, enzyme enzyme Enzyme 3 representatives to promote every steps of a specific enzyme, 1, 2, and auxiliary auxiliary auxiliary 3 required for each enzyme cofactor. The available examples, an adult food into more than all its activities need food, often get fat, which is obviously in the excess food is stored as fat, synthetic fatty acid increased. Fatty acid synthesis and protein, nucleic acid and sugars than simple; the raw material is acetic acid, but must be based on its active derivatives, Acetyl coenzyme A
The form into the metabolic pathway. Acetyl coa
A in vivo, a wide range of food, such as sugar, lipid and protein in Catabolism
That could generate acetyl coenzyme A. Before it is put into the fatty acid synthesis pathway, must be made by Acyltransferase
The catalytic and fatty acyl, first Carrier protein
Combined, then two carbon atom
Two carbon atoms are added, each with two carbon atoms, including the main raw material from acetyl coenzyme A synthesis Malonic acid
Single acyl coenzyme A, by seven steps, seven different enzymes and three different cofactors. The acetyl coenzyme A, seven and two carbon atoms (actually malonyl coenzyme A), but also a palmitoyl deacylase Catalytic effect
To complete a molecular. Palmitic acid
The synthesis of. This can be used as the main metabolic pathway of fatty acid synthesis even example, because many chemical reaction is not only gradually progressive, but also in stages to complete, which shows its complexity.
The complexity of metabolic pathways is also reflected in a substance in the body into a variety of metabolic pathways, can enter Synthesis and metabolism
Way, you can enter Catabolism
Some way, even the anabolic or catabolic pathway, which is not a. for example Acetyl coenzyme A
Not only can enter the tricarboxylic acid cycle three is oxidized to produce energy, but also in the synthesis metabolism, in addition to Synthesis of fatty acid
Besides, the main source of carbon atoms or ketone and steroids in molecules, but also synthesize some Amino acid
A, such as glutamic acid and microorganisms in arginine, lysine and other raw materials. In addition, acetyl coenzyme A in Acetylation
Play an extensive role role, such as acetyl amino sugar, acetylcholine
And the generation of acetyl carnitine in the.
Material metabolism Regulation of metabolism
The whole organism, or its organs, tissues and cells, must have a suitable environment, can make the material metabolism required for normal life. Once the external environment change in the in vivo environment must also be reflected with the material metabolism will have corresponding regulation and control, the metabolic pathway is correct, appropriate speed, Nutrients
The application and elimination of appropriate supply and metabolic products, in order to maintain the normal life to continue. Metabolism is mainly carried out within the cell, while the external effects of biological change first, followed by changes in the environment, which makes the cells affected by chemical reaction, resulting in metabolism should be adjusted. Therefore, the regulation of metabolism plays a role in organism, cells and molecules on the water.
Material metabolism The overall level of regulation
Material metabolism Close relationship
There is a close relationship between an organism and its living environment, the body's metabolism will vary with the environment, especially the effects of nutrient supply is more obvious. Eskimos live in the cold Arctic, mainly only edible animals, fish and other animal food, natural energy is the source of protein and fat, the body fat and protein Catabolism
Must be strong. While living in the mild region of the crowd, with more starchy grains as staple food, energy has come from the decomposition of glucose metabolism. Even living in the same area, due to the different feeding habits or supply shortages, often caused by deficiency of one or several nutrients, such as the old Chinese rice area due to consumption of long rice grinding and lack of vitamin B1. Vitamin B1 Thiamine pyrophosphate
The form is Pyruvate dehydrogenase
Coenzyme A and alpha ketoglutarate dehydrogenase, when vitamin B1 deficiency, pyruvate can decarboxylate into three tricarboxylic acid cycle complete oxidation, thus resulting in stacking, some of the symptoms of beriberi. Furthermore, the changes of the feeding can promote the chemical reaction of the enzyme changes in quantity; for example, infant milk as the main food, the gastric secretion of rennet more, this enzyme without food or eat less milk in the stomach of adults is almost absent, so some people in the consumption of milk after years it can not be very good, condensation and digestion, so diarrhea.
Material metabolism Exceptional case
In special circumstances, such as hunger or stress, the body must regulate metabolism, to change. The state of certain diseases can make the patient can not eat, if not replenish nutrients, especially glucose, immediately resulting in a hunger state. When hungry, metabolism will change, and gradually with time change, it can change from their blood glucose levels to see a sketch. During starvation, cut off the supply of nutrients in vitro, but in vivo without glucose; although the brain can adapt to the use of more or less Ketone
However, required red cell ATP is totally dependent on blood glucose decomposition in cells, so other organs of sugar Catabolism
The decomposition of protein decreased gradually, while strengthening to increase gluconeogenesis; while three tricarboxylic acid cycle can not run to generate ATP, so use a large amount of fat decomposition, the body energy needs are met. These metabolic changes are regulated by certain hormones. The hungry some metabolic parameters are listed in table 2-4-2. from table 2-4-1 can see the blood insulin levels decreased gradually, Glucagon
Improved; can also see the body increased significantly, but also can see Amino acid
The level of decline. This is undoubtedly the result of fat decomposition and increased gluconeogenesis etc..
Material metabolism Abnormal situation
Stress is the body to the outside stimulate abnormal adaptation. This stimulation may include some trauma, surgery, burns, renal failure, infection, cold and strong emotion. Any one of this kind of situation, in total performance in blood cortisol
and growth hormone
Although the secretion is not affected, insulin resistance in obvious results; lipolysis increased, the oxidation of many fat in tissues instead of glucose oxidation, thus accelerating the formation of ketone bodies, so that the energy metabolism changes; at the same time also had abnormal protein metabolism, the decomposition increased, decreased synthesis make the most of. Amino acid
Deamination in liver, the glucogenic carbon skeleton by gluconeogenesispathway generation and synthesis of amino sugar, urea nitrogen, resulting in a negative balance of patients, which may be related to cortisol level in vivo stress increased a lot.
As shown above, the body metabolism is always through neurohumoral to regulate the body, to deal with the abnormal situation encountered.
Material metabolism Regulation at the cellular level
Material metabolism Regulation system
Regulation system of 1 cells: the metabolism is affected by the environment of the body. Stimulation of external factors affecting first nerve, then transfer to the endocrine gland to secrete hormone, blood flow to various tissue cells by regulating its metabolism. The hormone to regulate cell metabolism in the matter. Although various hormones and body cells are in contact, but only to the target tissues Target cell
Hormonal regulation is also affected by the Feedback inhibition
The control, such as promoting secretion of hypothalamus thyroid hormone
The release of hormones, promote the release of the anterior pituitary thyroid stimulating hormone, in order to promote the synthesis of thyroid gland Thyroglobulin
As the synthesis of thyroxine, and Three Triiodothyronine
The raw material. But the blood thyroxine in turn can inhibit the release of the anterior pituitary thyroid stimulating hormone, can also inhibit the secretion of hypothalamus Thyrotropin releasing hormone
. In addition, the growth hormone secretion of hypothalamus and pancreas release inhibin
Can inhibit the secretion of thyrotropin releasing hormone.
Material metabolism Hormone receptor
Highly hormone Specific
That only acts on target cells, which means that the target cells must have a special structure of the hormone can be identified; this structure is the hormone receptors, hormone receptor in some cells on the surface, but also some in the cytosol, in cell surface
Is a water soluble peptide and amine hormone receptor exists in the cytosol is easy by membrane Fat soluble
Steroid hormone receptor. They may have been some specific glycoprotein, has high specificity and affinity for the hormone molecule. A hormone can selectively recognize their specific receptors, and their combined into composite. This complex will lead to" Second messenger
"Production or release. The second messenger will transfer carry complex hormone and receptor information for specific enzymes or molecular systems, the hormone's mission to be realized, this is the intracellular second messenger regulation of specific enzymatic reactions or specific gene expression.
Material metabolism Expression
Hormone (first messenger) + receptor, hormone receptor complexes - - - - - the second messenger pathway
Material metabolism The role of cyclic adenosine monophosphate
In many cases, the second messenger is actual ring 3 ', 5' - monophosphate, abbreviated as cAMP.
CAMP how to trigger specific enzymatic reactions, available glycogen on glycogen decomposition function to explain. In the muscle activity of adrenaline on cell membrane receptor binding and activation of cAMP generation and cAMP immediately triggered cascade; glycogenolysis (Figure 2-4-4), while inhibiting glycogen formation. When the muscle activity decreases when the hexosephosphate due to no need to produce ATP and cumulative, that will in turn activate glycogen synthase B to produce glycogen synthetase a to promote glycogen phosphorylase, and inhibition of B into phosphorylase a. CAMP also affected the nucleus, its function is through the activation of specific protein kinase, promote non histone phosphorylation and falling down from the binding site with DNA, which is a repressor of genes to be expressed.
Material metabolism Effects of sex hormones on target cells
Steroids are fat soluble substances, can pass through plasma membrane
And enter the cell; its receptor exists in the cytosol, and with cAMP as the second messenger. For example, Estradiol
The target cells and breast, with a specific 4S in the cytosol protein (i.e. receptor) with the compounds into 5S (i.e. second messenger) after entering the nucleus, and the role of the chromosome and promoting the formation of mRNA, the synthesis of specific proteins..
Material metabolism Regulation at the molecular level
Material metabolism chemical reaction
The various chemical reactions in metabolism by enzymes to change, so the structure of enzyme molecules and the synthesis, degradation rate of change is the most direct factor in the regulation of metabolism. Enzyme molecular structure change is very fast, which occur in seconds, and the synthesis and degradation is slow, a few hours can be achieved. Structural changes include allosteric and modification of the molecule, has great relationship with the body's needs and the environment, the synthesis and degradation, especially the synthesis involves the role of genes.
Material metabolism By adjusting the allosteric enzyme molecule
A metabolic pathway occurs or disappeared and the rate of change, depends on the regulation of enzyme activity. While the activity of enzyme, temperature, pH, in action and auxiliary factors are constant, and depends on its molecular structure, with allosteric regulation of enzyme properties, is often called the Allosteric enzyme
. At the beginning of allosteric enzyme metabolic pathways are often located in or near the promotion is one important and irreversible reaction, the molecular structure can be changed by some excitement or inhibition of effector molecules. Molecular allosteric enzyme has some specific structures, can be combined with some small molecules, such as the role of the end product, and, Metabolic intermediates
The product or even other metabolic pathways; once combined, the conformation of enzyme molecules that will change and affect its activity; combination of different molecules, produce different results. stay Catabolism
For example, in glycolysis, ATP is the action of phosphofructokinase, and allosteric modulators. When the body needs to glycolysis for energy, and ATP Phosphofructokinases
With the promotion of glycolysis, but at the level of ATP increased to more than needed, it can inhibit phosphofructokinase, thus glycolysis slows or stops. Citrate is inhibitor of phosphofructokinase, has the effect of lowering the rate of glycolysis.
Material metabolism Material combination
Allosteric enzymes can be combined with a variety of small molecules, but the metabolic pathways associated with the end product is a combination of its unique properties. When the end product is more than needed, and enzyme molecules change their conformation, thus inhibiting its activity; this is the feedback inhibition. Many examples of allosteric feedback inhibition, the earliest found for bacteria to promote L threonine into enzyme system of L. This system is composed of five kinds of enzymes, to Threonine dehydratase
This is a beginning of the enzyme transformation. Advanced glycation end products of threonine dehydratase can be inhibited by isoleucine transition process, which of course is generated; excessive occurrence of isoleucine. Isoleucine is a specific inhibitor of threonine dehydratase, did not inhibit other enzyme system, and other intermediate products of threonine dehydratase had no inhibitory effect. Isoleucine and threonine dehydratase by non covalent bonds with the enzyme molecules to form reversible binding, so when needed and can be separated from the isoleucine binding site, enzyme activity recovery. Thus, feedback inhibition apparently by allosteric enzyme molecules to regulate metabolism.
Material metabolism By adjusting the molecular modification of enzyme
The enzyme molecule contains a variety of groups, some can be removed or added, others can change through the interaction; these modifications to affect the enzyme activity, such as add or remove phosphate and sulfur hydrogen and two sulfur bond mutual transformation are familiar examples of modification of enzyme molecules. Synthesis and decomposition of spermatogonia is through glycogen synthase and Glycogen phosphorylase
With the dephosphorylation regulated. I D and glycogen synthase exists in two types; type I to remove phosphate and active, but the protein kinase phosphorylation is a D type activity. In the presence of glycogen phosphorylase by a and B in two forms, its phosphorylation or dephosphorylation on activity and glycogen synthase opposite; phosphorylase a is phosphorylated by phosphorylase phosphatase in type. hydrolysis
The dephosphorylated, becomes inactive B.
Material metabolism Through gene regulation
The enzymes and other substances, also has its synthesis and Catabolism
And through the enzyme protein metabolism, can affect the content of intracellular enzyme, and metabolic regulation and speed. The enzyme half-life is very short, if there is no synthesis, content of intracellular enzyme was decreased gradually, the influence factors in the synthesis of enzyme action, metabolites, hormones and drugs etc.. These factors are synthesized by gene to regulate the enzyme. Many examples of action effects of enzyme synthesis, such as low protein and high carbohydrate diet to eat people, content of amino acids in the liver enzyme decomposition must be very low, due to not much use without a large number of synthetic enzyme. Once the change of diet and high protein diet, a day in the liver of decomposition Amino acid
The content must be increased. This shows that the synthesis of liver cell enzyme as the dietary supply of nutrients and the nature, the actual role in the role of gene and the required enzymes have been synthesized; this effect is generally called enzyme induction (Figure 2-4-7).
Material metabolism The metabolic pathway
Effect of A gene and generating enzyme required for E metabolic pathway in A 1, E 2 and E 3, A, C and B were transformed into D. Induction of enzyme, in bacteria is also common, for example, Escherichia coli can grow in the medium containing glucose in the lactose fermentation
And the growth in the medium containing lactose or methyl galactose in person; this is because lactose or galactose methyl effect on gene and induced the formation of beta galactosidase results.
The metabolites by gene Enzyme protein
The regulation of the synthesis, the most common is Feedback inhibition
. When a metabolic end product more than needed, and Regulation of enzyme
Binding caused by feedback inhibition, resulting in reduced synthesis of this enzyme in the metabolic pathway.
In vivo effects of higher animal protein synthesis
The information will be passed to the hormone cell Recipient
, Second messenger
And then by the gene. Gene regulation
Protein synthesis. For example, insulin can promote synthesis and inhibit the decomposition of protein, which is likely to make Glycolysis
The content of fatty acid synthesis and metabolism of enzyme in cells increased, and glucocorticoid promote Muscle protein
The decomposition of the resulting Amino acid
Through in the liver cells Gluconeogenesis
The generation of sugar, so the effect of hormone is the result of amino acid Catabolism
Synthesis and gluconeogenesis enzymes.
Material metabolism Xenobiotics
The vast majority of drugs and poisons are xenobiotics, can induce decomposition of their enzymes to lift its role is not conducive to life. Many drugs and poisons in liver Biotransformation
Promote; biotransformation enzymes, often called microsomal enzyme activation, are not potential or existing enzyme precursors, but induced by xenobiotics and re synthesis. This is undoubtedly a role by regulating genes. We now know, drugs and poison
Inducing agents can be divided into two types of phenobarbital and polycyclic hydrocarbon species, the former can stimulate microsomal enzymes is much higher than the latter.
In the above, metabolic regulation is divided into whole, cell and molecular level of three to discuss, but actually regulate metabolism is always followed by nerves, hormones and genes, and finally implement the enzyme molecules to achieve.