A cell
There are about 40 trillion -60 trillion human cells. The average diameter of cells is 10-20 microns. The largest is the mature egg cell, with a diameter greater than 0.1mm; The smallest is platelets with a diameter of only about 2 microns. Most cells consist of cell membrane, cytoplasm and nucleus. The nucleus is the center of regulating cell function.
In the human body, 1 100 million cells die every minute. The life span of intestinal mucosal cells is 3 days, that of hepatocytes is 500 days, that of platelets is about 7- 14 days, and that of nerve cells is several decades. Some white blood cells in the blood can only live for a few hours. The most amazing thing is the nerve cells in the brain. The transmission speed of nerve impulses exceeds 400 kilometers per hour, which is equivalent to half the speed of Boeing 777.
The second organization
The tissues of human body include muscle tissue, connective tissue, epithelial tissue and nerve tissue.
Three organs
There are 100 organs in the human body, and their functions are different.
Four or eight systems
Digestive system, nervous system, exercise system, immune system, endocrine system, genitourinary system, circulatory system and respiratory system.
Wunaonao
The brain is composed of about 1400 million cells and weighs about1400 grams. The thickness of cerebral cortex is about 2-3 mm, with a total area of about 2200 square centimeters. Every day, 654.38+ million brain cells die (the more you don't use your brain, the more you die).
The amount of information stored in a person's brain is equivalent to 6,543.8+0,000 books in 6,543.8+0,000 libraries. The person who knows how to use his brain best only uses 10% of his brain capacity in his life. The main component of the human brain is water, accounting for 80%. Although the brain only accounts for 2% of the body weight, the oxygen consumption is 25% of the whole body oxygen consumption, and the blood flow accounts for 15% of the cardiac output. The blood flowing through the brain is 2000 liters a day. If the energy consumed by the brain is expressed by electric power, it is equivalent to about 25 watts.
Six skins
The total area of adult skin is about 2 square meters. There are about 3 million sweat glands and 65.438+0 billion nerve endings hidden under the skin. Men have/kloc-0.6 million hair follicles, while women have only 4 million, so men have more hair than women. When people walk, they will affect about 54 muscles, and a smile will also affect about 17 facial muscles.
Seven bones
The human skeleton consists of 206 bones, including 29 skulls, 5 1 trunk bones and 26 limbs bones. People's bones can't fully develop and mature until about 25 years old, and adult bones account for 1/5 of body weight.
Eight muscles
There are about 639 muscles in the human body, which are composed of about 6 billion muscle fibers. The average person's muscle accounts for 35-40% of the body weight. The total length of intramuscular capillaries is 654.38+ million kilometers, which can circle the earth for two and a half times.
Nine blood
The total blood volume of human body is about 8% of body weight. If the blood loss of healthy people does not exceed 10%, they can generally recover quickly; If an acute blood loss exceeds 20%, blood pressure will drop and all kinds of life activities of the body will be affected; If the acute blood loss exceeds 30%, it will be life-threatening if it is not rescued in time.
A drop of blood circulates in the human body for 22 seconds.
The chemical composition of the human body
Water accounts for 65% of human body weight. An adult weighing 70kg weighs only 25kg after dehydration, including 3kg of carbohydrate, 7kg of fat, 3kg of protein 12kg and 3kg of mineral salt.
Shiyi food
The purpose of food intake is to supplement seven nutrients in food: protein, fat, sugar, vitamins, minerals, dietary fiber and water. These seven nutrients are essential substances to sustain life. Without one, people will die.
Fine cell
Cells are the structural and functional units of the human body. There are about 60 trillion cells, which are composed of 100 kinds of tissues and organs. The average diameter of cells is between 10-20 microns. Except mature red blood cells, all cells have a nucleus, which is the center of regulating cell function. The largest is the mature egg cell, with a diameter greater than 0.1mm; The smallest is platelet, which is only about 2 microns in diameter. The life span of intestinal mucosal cells is 3 days, that of liver cells is 500 days, and that of nerve cells in brain and bone marrow is several decades, almost equivalent to that of human body. The life span of red blood cells in blood is 120 days, white blood cells are only 9 days, and platelets are only 4 days. In the whole human body, 654.38 billion cells die every minute, of which 30 million are blood cells. The most amazing thing is that the nerve impulse transmission speed of nerve cells in the brain exceeds 400 km/h, which is equivalent to half the speed of Boeing 777.
Organ officer
About 100 organs are distributed all over the human body, including more than 800 kinds of tissues. They have various functions: digestion, detoxification, immunity, regeneration, automatic adjustment and so on.
blood
The total blood volume of human body is about 8% of body weight. If a blood loss exceeds 20% of the blood volume in the human body, life activities will be blocked. Healthy people can generally recover quickly when the blood loss at one time does not exceed 10%. A drop of blood circulates in the human body for 22 seconds.
The chemical composition of the human body
Water accounts for 63% of human body weight. An adult weighing 70 kg will only weigh 25.9 kg after dehydration. Among them, carbohydrate is 3 kg, fat is 9. 1 kg, protein 15.4 kg and mineral salt 1.4 kg.
muscle
The human body has about 639 muscles. It consists of about 6 billion muscle fibers, the longest is 60 cm, the shortest is only about 1 mm, the big muscle weighs 2000 grams, and the small muscle is only a few grams. The average person's muscle accounts for 35%-40% of the body weight. The total length of capillaries in muscle can reach 654.38+ million kilometers, which can circle the earth twice and a half times.
skeleton
It is connected with the muscles responsible for body movements. The human skeleton consists of 206 bones, including 29 skulls, 5 1 trunk bones and 26 limbs bones. People's bones can't be fully developed until they are about 25 years old.
Skin skin
The total area of adult skin is about 2 square meters. There are about 3 million sweat glands and 65.438+0 billion nerve endings hidden under the skin. Men have/kloc-0.6 million hair follicles, while women have only 4 million, so men have more hair than women. There are 450 pairs of exercise muscles. Walking affects about 54 muscles, and a smile also affects about 17 facial muscles.
Big head
The brain is composed of about 65.438+0.4 billion cells, weighing about 654.38+0.400 g, and the thickness of the cerebral cortex is about 2-3mm, with a total area of about 2,200 square centimeters. It is estimated that 654.38+0000 to 654.38+000 million brain cells die every day (the more unused brain cells, the more brain cells die). The information storage capacity of a person's brain is equivalent to 10,000 libraries10,000 books. The person who is best at using his brain only uses 65,438+00% of his brain capacity in his life. The main component in the human brain is water, accounting for 80%. Although it only accounts for 2% of human body weight, its oxygen consumption accounts for 25% of the whole body oxygen consumption, and its blood flow accounts for 15% of the cardiac output. The blood flowing through the brain is 2000 liters a day. If the energy consumed by the brain is expressed by electric power, it is equivalent to about 25 watts.
Respondent: 1 tyar 1- trainee wizard level 2 -2 1 16:03.
Various tissues and organs composed of 100 cells. The average diameter of cells is between 10-20 microns. Except mature red blood cells, all cells have a nucleus, which is the center of regulating cell function. The largest is the mature egg cell, with a diameter greater than 0.1mm; The smallest is platelet, which is only about 2 microns in diameter. The life span of intestinal mucosal cells is 3 days, that of liver cells is 500 days, and that of nerve cells in brain and bone marrow is several decades, almost equivalent to that of human body. The life span of red blood cells in blood is 120 days, white blood cells are only 9 days, and platelets are only 4 days. In the whole human body, 654.38 billion cells die every minute, of which 30 million are blood cells. The most amazing thing is that the nerve impulse transmission speed of nerve cells in the brain exceeds 400 km/h, which is equivalent to half the speed of Boeing 777.
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