Nicotine, commonly known as nicotine, is an alkaloid found in the family Solanaceae (Solanum), an important component of tobacco, and a representative of N-choline receptor agonists. The central nervous system has effects and has no clinical application value. Nicotine Effects
Nicotine can be addictive or dependent. Repeated use of nicotine also increases heart speed and hypertension and reduces appetite. Large doses of nicotine can cause vomiting and nausea, and death can occur in severe cases. Tobacco usually contains nicotine. E-cigarettes also contain nicotine, a harmful substance in traditional tobacco.
When nicotine enters the body, it is transmitted through the blood and can cross the blood-brain barrier. It takes an average of 7 seconds to reach the brain after inhalation. The half-life of nicotine in the human body is about 2 hours. The amount of nicotine the body obtains through smoking is affected by many factors, including the quality of the smoke, whether it is inhaled, and whether a filter is used.
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Chewing, mouth-filling, and inhaling tobaccos are more effective at entering the body through the way they are contained between the lips and gums and directly inhaled through the nose. The liver is the organ that mainly metabolizes nicotine. The breakdown enzyme is Cytochrome P450 (mainly CYP2A6, CYP2B6 can also act on nicotine), and the metabolite product is cotinine.
Nicotine acts on nicotinic acetylcholine receptors, especially the receptors on the autonomic nerve ((α1) 2 (β4) 3) and the receptors on the central nervous system ((α4) 2 (β2) 3). And other locations, the latter located in the central nervous system. At low concentrations, nicotine increases the activity of these receptors, and nicotine has a small direct effect on other neurotransmitters. Suppressed at high concentrations.
Nicotine Effects: Central Nervous system
Nicotine can be combined with nicotine acetylcholine receptors to increase the number of neurotransmitters and increase dopamine in the brain. The nicotine actually creates a sense of emptiness in the brain. After increasing the concentration through smoking and other methods, the emptiness brought about by rapid nicotine metabolism is alleviated. Smoking can cause people to feel confident, relax, and other false hallucinations. In the end, they may become addicted to smoking.
Tobacco smoke contains a combustion monoamine oxidase inhibitor (Monoamine oxidase inhibitor), monoamine oxidase decompose monoamine neurotransmitters, dopamine, norepinephrine and serotonin.
People who have been exposed to nicotine for a long time through smoking can positively regulate α4β2 nicotine acetylcholine receptors in the cerebellum and brainstem.
Peripheral nervous system
Nicotine stimulates the sympathetic nerves and stimulates the visceral nerves to affect the perinephric medulla and release adrenaline. The parasympathetic ganglion fibers release acetylcholine, which acts on the nicotinic acid acetylcholine receptor, causing it to release adrenaline and adrenaline to the blood.
Nicotine and adrenal medulla of nicotine after receptor binding will increase the amount of adrenaline in the blood. Through the results with the receptor, the nicotine depolarizes the cells, the calcium ions flow in through the calcium ion channels, and the calcium ions promote the neurons to release epinephrine and orciprenaline to the blood in a cytotoxic manner, and the adrenaline in the blood increases.
Resulting in a faster heartbeat, higher blood pressure, and faster breathing, just like in the case of high blood sugar. Cotinine is a by-product of nicotine metabolism and can remain in the blood for 48 hours. It can be used as a substance to test whether a person smokes.
Physical and chemical properties
It is an unpleasant, bitter, colorless and transparent oily liquid substance. Molecular formula C10H14N2, soluble in water, ethanol, chloroform, ether, oil, nicotine can penetrate into the skin. The nicotine in the free radical state has a burning point below the boiling point. At low vapor pressure in the air, the gas reaches 308K (35°C 95°F) and will burn.
For this reason, nicotine is mostly produced when a cigarette is lit, but the amount of inhaled is sufficient to produce the desired effect. Nicotine is optically active and has two optical isomers. The viscosity is 2.7 mPa · s at 25°C, the viscosity is 1.6 mPa · s at 50°C, the surface tension is 27.5 dynes/cm at 25.5°C, and the surface tension is 37.0 dynes/cm at 36.0°C.
Harmful components in cigarette smoke include carbon monoxide, nicotine and other alkaloids, amines, nitriles, alcohols, phenols, alkanes, alkenes, carbonyl compounds, nitrogen oxides, polycyclic aromatic hydrocarbons, heterocyclic compounds, and heavy metal elements.
They have multiple biological roles, including:
- Inflammatory irritation to the respiratory mucosa: such as aldehydes, nitrogen oxides, and olefins.
- The toxic effect on cells: such as nitriles, amines, heavy metal elements.
- Addictive effects: alkaloids such as nicotine.
- Carcinogenic effects on the human body: such as benzopyrene of polycyclic aromatic hydrocarbons and cadmium, dimethylnitrosamine, β-naphthylamine, etc.
- It has a cancer-promoting effect on the human body: such as phenolic compounds.
- It causes red blood cells to lose oxygen-bearing capacity: such as carbon monoxide.
Tobacco’s harmful substance content is usually evaluated by “tobacco tar and carbon monoxide”, which requires
The smoke tar produced by each cigarette is less than 15 milligrams, and the smoke on the market has been measured several times. Calculated by smoking 20 cigarettes a day, of which one quarter is inhaled, the amount of cigarette tar inhaled by smokers per day is about 120-200 mg. The combined action of harmful substances in cigarette tar is a major threat to human cancer.
The various carcinogens that makeup cigarette tar are caused when the amount of inhaled reaches a certain level
Cancer initiators, carcinogens and synergistic carcinogens can accelerate carcinogenesis.
Toxicity Analysis Harm dispute
Nicotine, which has been closely linked to “death” and “cancer” for nearly a century, has now received a lot of new attention, and many experts have justified its name. It is believed that the nicotine in cigarettes is not too harmful, and the real carcinogens are tar and carbon monoxide.
Zhang Yifang, vice president of the China Association for Smoking and Health, said: “Although there is no certainty about whether nicotine can cause cancer in the scientific and technological circles, it is certain that nicotine can make people addicted to tobacco, and smoking will affect people’s health. It’s true.”
Moreover, he also said that in fact, it is not important whether nicotine in cigarettes is carcinogenic or harmful substances such as tar and carbon monoxide in cigarettes. When smoking, there is no way for smokers to make nicotine and tar and carbon monoxide harmful. Material separation, and what is really addictive is this nicotine.
Who smokes specifically to absorb tar and carbon monoxide? Therefore, even if nicotine does not have a carcinogenic effect, it is at least an accomplice to carcinogens such as tar and carbon monoxide. People develop cancer due to smoking, and nicotine is absolutely inseparable.
Nicotine can stimulate peripheral vasoconstriction, increase heart rate, increase blood pressure and increase breathing speed, and promote the occurrence of cardiovascular diseases such as hypertension and stroke.
Harm of Smoke
Nicotine is a highly toxic substance. The oral LD50 of rat nicotine is 50mg / kg, and the mouse nicotine LD50 is 3.3 mg/kg. The nicotine contained in a cigarette can kill a mouse, and the nicotine in 20 cigarettes can kill a cow.
If a person smokes a large amount of nicotine ( 50 to 70 milligrams, which is equivalent to the nicotine content of 40 to 60 cigarettes ) at one time, it may cause death. If you inject a cigar or three cigarettes of nicotine into a person’s vein for 3 to 5 minutes, you can die.
Tobacco is harmful not only to higher animals, but also to lower animals, so it is also a major component of agricultural pesticides. Therefore, “Vipers do not bite smokers.” Because they smell the bitter smell of smoking, they avoid flying away. By the same token, passive smokers also feel uncomfortable with the smell of smoke.
Acute poisoning deaths have already occurred in China. If you smoke too much, you will be drunk and spit yellow water and die. To this end, Emperor Chongzhen ordered a smoking ban.
It has also been reported abroad: youth in the Soviet Union smoked for the first time and died after smoking a large cigar. A 40-year-old healthy man who smoked in the UK for a very important job, smoking 14 cigars and 40 cigarettes overnight, felt uncomfortable in the morning and died after being rescued by a doctor.
France holds a smoking contest, the winner in the club he sucked in a 60 Zhi cigarettes after, not enough time to accept the award that is dead, the other dying because of all those who participate in the competition, to the hospital.
There are many people who smoke more than one box (20 sticks) of cigarettes a day.
Some people smoke a lot but do not poison. The content of nicotine greatly exceeds the lethal amount of humans. However, there are very few deaths caused by acute poisoning.
Part of the nicotine is neutralized by the smoke poison formaldehyde, and most of them are not continuous smoking. This nicotine enters the body intermittently and slowly.
In addition, after the cigarette is lit, 50% of the nicotine diffuses into the air with the smoke, 5% is thrown away with the cigarette end, 25% is destroyed by burning, and only 20% is absorbed by the body.
Nicotine is quickly detoxified and excreted in the body. Coupled with long-term smokers, the body develops tolerance and addiction to nicotine, which makes people addicted to smoke.