The purpose of "salt and health" research is to understand the importance of salt to our human body and how to eat and use salt reasonably. (2) The significance is to make us use salt better, more reasonably and healthier.
Introduction; Too much salt can lead to high blood pressure. According to experts' investigation, there is a certain relationship between salt intake and the incidence of hypertension. The more salt you eat, the higher the incidence of hypertension. Eskimos in Alaska have very low salt content and basically have no hypertension, while residents in northern Japan who have a daily salt content of about 20 grams have a surprisingly high incidence of hypertension.
"Shennong Materia Medica" records: "Salt is applied to beriberi, cleaning and strengthening teeth, and treating various skin diseases." Washing feet with salt and perilla root soup can cure beriberi. Scrubbing the skin with salt water can make the skin healthy and enhance resistance.
Excessive salt can lead to heart disease. There is such a record in Neijing: "More salt makes the pulse thick and discolored". "The taste is too salty, which hurts the bones and depresses the heart." Too salty makes arterioles contract, which is harmful to the heart.
The main reason why we choose "salt and health" is that we use salt every day, and salt plays a very important role in our health. The purpose of "salt and health" research is to understand the importance of salt to our human body and how to eat and use salt reasonably. (2) The significance is to make us use salt better, more reasonably and healthier. How can I eat salt reasonably? Salt is also an indispensable substance for normal physiological activities of human body.
Main body: salt: one of the most commonly used seasonings in cooking, the scientific name is sodium chloride (chemical formula NaCl), which is a white crystal with strong hygroscopicity and should be stored in a dry place. Salt is also an indispensable substance for normal physiological activities of human body, 3~5 grams per person per day. Salt is widely distributed in nature. Seawater is rich in salt. Salt wells and mines in salt lakes also contain salt. China is rich in salt resources. Salt making method: salt is dried in seawater or boiled in well water or salt lake to precipitate salt crystals. The salt made in this way has many impurities and is called raw salt. Crude salt can be dissolved, precipitated, filtered and evaporated to produce refined salt. The salty taste of salt is produced by sodium ions, but the effect of salt on human body is not only seasoning, but also physiological needs such as maintaining osmotic pressure balance. If it is only salty, not any salty salt can replace it. Many salts are toxic to human body.
Salt is indispensable in people's life. The total amount of sodium ions contained in adults is about 60g, of which 80% exists in extracellular fluid, namely plasma and intercellular fluid. Chloride ion also mainly exists in extracellular fluid. The physiological functions of sodium ion and chloride ion are mainly as follows.
Sodium ion and chloride ion are the main ions to maintain the osmotic pressure of extracellular fluid, while potassium ion and hydrogen phosphate ion are the main ions to maintain the osmotic pressure of intracellular fluid. In the total amount of extracellular cations, sodium ions account for more than 90%, and chloride ions account for about 70% of the total amount of anions. Therefore, salt plays an important role in maintaining osmotic pressure and affects the flow direction of water in human body.
Participate in the regulation of acid-base balance in the body. Sodium bicarbonate formed by sodium ions and bicarbonate ions has a buffering effect in the blood. At this time, chloride ion and bicarbonate ion also have a balance between plasma and red blood cells. When bicarbonate permeates from red blood cells, the number of anions in red blood cells decreases, and chloride ions enter red blood cells to maintain electric balance. or vice versa, Dallas to the auditorium
Chloride ion participates in the formation of gastric acid in the body. The gastric juice is strongly acidic, and the pH value is about 0.9 ~ 1.5. Its main components are pepsin, hydrochloric acid and mucus. The parietal cells in the gastric gland can secrete hydrochloric acid, and the cell wall can import HCO3- into the blood and secrete H+ into the gastric juice. At this time, Cl- enters the gastric juice from the blood through parietal cells to maintain the electric balance. This concentrated hydrochloric acid is because there is a mucous cell in the gland of the stomach, and the mucus secreted by it forms a mucous layer with a thickness of about (1 ~ 1.5) mm on the surface of the gastric mucosa, which is usually called the barrier of the gastric mucosa. Under the attack of acid, the gastric mucosa will not be digested by digestive enzymes and form ulcers. However, drinking alcohol will weaken the barrier function of gastric mucosa and often increase the possibility of causing gastric ulcer.
In addition, salt can also maintain the normal excitability of nerves and muscles. When a large amount of extracellular fluid is lost (such as massive bleeding and sweating) or food is short of salt, the content of sodium ions in the body decreases, and potassium ions enter the blood from cells, which will lead to blood thickening, less urine and yellow skin. Salt is an indispensable thing in our life. Where does the salt come from? A long time ago, people used sea water to dry salt, salt lake salt water to dry salt, and salt spring salt water to fry salt. Of course, today we also use seawater and salt lake water to make salt. There is also a part of iodized refined salt, which is obtained by another way-mining rock salt and processing.
Rock salt is also called rock salt. It is a special kind of stone and a very useful mineral. Rock salt is transparent or translucent, easily broken, a bit like rock sugar, but salty. Rock salt is buried at a depth of several hundred meters to several thousand meters underground, and is often accompanied by gypsum, mirabilite and potassium salt. It was formed by evaporation and crystallization of seawater or lake water tens of millions of years ago.
It is also interesting to talk about the exploitation of rock salt. Clever scientists take advantage of the fact that rock salt can be dissolved by water, and workers can extract salt without going down the mine. Well, the worker's uncle went underground for hundreds to thousands of meters from the ground. Once he reached the lower part of a rock salt mine, he used cement to build a big steel pipe, then inserted a small pipe into the big steel pipe and injected water from the big pipe. When water flows into the salt layer, the salt is dissolved into brine, and the brine returns to the ground along the small tube. This process is called "solution mining" and it is an advanced mining method now. The brine collected on the ground is collected in several ponds on the ground through pipelines, and lime and soda ash are added to precipitate and purify the brine to remove all kinds of impurities, and then it can be sent to the salt plant to produce salt. Scientists also make full use of the flowing characteristics of salt water to transport salt plants by pipeline, saving labor and money!
Modern salt is made by "vacuum salt making" technology. Pure brine is injected into the evaporation tank, and high-temperature steam heats the brine through heat exchange, so that the water in the brine evaporates and the salt crystallizes. Scientists also use the principle of lowering the boiling point of liquid under the condition of low air pressure to reduce the heat energy consumption and make the salt crystallize out as soon as possible by reducing the air pressure in the evaporation tank. This is the "vacuum salt making" technology.
The production of salt is continuous, and the salt just produced is still a salt slurry. Excess brine should be thrown out by centrifugal glue and returned to evaporation tank for recycling. Dehydrated salt is still wet, so it should be dried with dry hot compressed air. If dried salt is used in industrial production, it can be packaged and transported. If it is used in food, there must be a key process-"iodization". If people lack iodine, they will suffer from iodine deficiency (IDD), neck disease and mental damage. Iodized salt is packaged and transported, and then enters thousands of households and our bodies. Salt is a necessity for people. Su Shi, a great writer in the Song Dynasty, wrote in his poem: "Don't you forget the taste? You can eat without salt in March?" If you don't put some salt in the dish when you eat, even the delicacies are like chewing wax. Salt is not only an important condiment, but also an indispensable substance to maintain the normal development of human body. Adjust the balanced distribution of water in human body, maintain osmotic pressure inside and outside cells, participate in the formation of gastric acid, promote the secretion of digestive juice, and stimulate appetite; At the same time, it also ensures the pH necessary for the action of pepsin, maintains the balance of pH in the body and the normal circulation of body fluids. People cannot live without salt. Eating too little salt can also lead to low sodium content in the body, loss of appetite, weakness of limbs and dizziness. In severe cases, there will be anorexia, nausea, vomiting, increased heart rate, weak pulse, muscle spasm, blurred vision, weakened reflex and other symptoms. In ancient times, the Netherlands, Sweden and other countries stipulated that people who violated the criminal law were not allowed to eat salt as punishment for a period of time.
However, eating too much salt is also harmful to the human body. The results of scientists' research show that salt can "replenish water" to the human body, that is to say, salt has a certain adsorption force on water. If there is more salt in the human body, it is necessary to increase the water accordingly, so that too much water stays in the body, thus causing high blood pressure. Someone has investigated the eating habits of residents in northern Tokyo, Japan. They eat an average of 25 grams of salt every day, and people with hypertension account for 30 ~ 40% of all residents. In other parts of the world, people only eat 5 ~ 15g of salt every day, and only 8 ~ 10% of them suffer from hypertension. Eskimos living in the Arctic Circle eat less than 5 grams of salt every day, and almost no one suffers from high blood pressure. Therefore, experts suggest that adults should not eat more than12g of salt every day.
Conclusion: Salt is indispensable in people's life. The salty taste of salt is produced by sodium ions, but the effect of salt on human body is not only seasoning, but also physiological needs such as maintaining osmotic pressure balance. Salt also maintains the normal excitability of nerves and muscles. When a large amount of extracellular fluid is lost (such as massive bleeding and sweating) or in food.
Abstract: We use salt every day, which plays a very important role in our health. Too much salt can lead to high blood pressure and too much salt can lead to heart disease. Salt is also an indispensable substance for normal physiological activities of human body. Salt also maintains the normal excitability of nerves and muscles. The main ionic salts of osmotic pressure play an important role in maintaining osmotic pressure and affecting the flow of water in human body. Salt is one of the most commonly used condiments in cooking. White material on the surface of grapes can be removed; It can remove the sediment that is difficult to remove from the bottom of the cup after it has been placed for a long time.
Postscript: Review and summary: white material on the surface of grapes can be removed, and the sediment that is difficult to remove at the bottom of the teacup can be removed if the tea is put in the teacup for a long time. The tutor not only guides us seriously, but also constantly inspires us to help us complete the task together when we encounter difficulties. When we visited our biology teacher, he answered our questions enthusiastically and positively. I would like to express my heartfelt thanks here.
Key words: health, function, seasoning, experiment.