1. Chemical composition
Water accounts for 65% of human body weight. An adult weighing 70kg has only 25kg after dehydration, including 3kg of carbohydrate, 7kg of fat, 2kg of protein/kloc-0 and 3kg of mineral salt.
2. 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. A healthy person can generally recover quickly when the blood loss does not exceed 10% at a time.
3. Muscles
There are about 639 muscles in the human body. It consists of about 6 billion muscle fibers, the longest of which is 60 cm, and the shortest is only about 1 mm. Large muscles weigh 2000 grams, while small muscles weigh only a few grams. The average person's muscle accounts for 35%-40% of the body weight. The total length of capillary in muscle can reach100000 km, which can circle the earth for two and a half times.
4. bones
Bones are hard tissues in or on human or animal bodies. There are two kinds: the bones of human and higher animals are in the body and consist of many bones, called endoskeleton; The hard shell of arthropods and mollusks and the scales and armour on the body surface of some vertebrates (such as fish and turtles) are called exoskeletons. The skeleton usually refers to the endoskeleton. Skeleton is a hard organ that constitutes the endoskeleton of vertebrates. Its function is to exercise, support and protect the body. Making red blood cells and white blood cells; Store minerals.
Bones are made up of various shapes and have complex internal and external structures, so that bones can keep hard while reducing weight. One of the components of bones is mineralized bone tissue, and its interior is a hard honeycomb-like three-dimensional structure; Other tissues include bone marrow, periosteum, nerves, blood vessels and cartilage. The skeleton of the human body plays a role in supporting the body and is a part of the human motion system. Adults have 206 bones. Bones are generally connected by joints and ligaments.
5. Brain
The brain is composed of about 1400 billion cells, weighing about1400 g, the thickness of cerebral cortex is about 2-3 mm, and the total area is about 2,200 square centimeters. It is estimated that brain cells will die every day from 1000 to1000,000 (the more brain cells are not used, the more brain cells will die). The capacity of a person's brain to store information is equivalent to 10,000 libraries with a collection of10 million volumes. The person who is the best at using his brain only uses 10% 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's oxygen consumption, and its blood flow accounts for 15% of the blood output of the heart. The blood flowing through the brain in one day is 2000 liters. The energy consumed by the brain is equivalent to about 25 watts if expressed by electric power.
Baidu encyclopedia-human body structure