What's inside the Blood? 

Source of pictures: Pixabay.com

Daniel ran to his mother without even putting down his schoolbag when he came home from school. Having seen his flustered face, mom was worried something serious had happened. Daniel asked nervously, "Mom, I lost a lot of blood today. Is there anything that can bring the blood back into my body?" Mom quickly took his hands and asked, "Where did you bleed? Got injured?" Daniel answered in a low voice, "I had a nosebleed in class break this afternoon. Then I went to the infirmary, the doctor stopped the bleeding and said I was fine."

Mom touched his nose and said, "Maybe it's been a bit dry lately and you got too much hi-calorie food."

Daniel was still a little worried and asked, "Mom, can the blood I lost back my body? My classmates said that everyone has a fixed amount of blood. There's less blood in my body as it's bleeding out. Once all the blood runs out of my body, I'll die."

Mom was a little amused and explained, "How can this happen? Human body is powerful in producing blood. Although we bleed, our body has hematopoietic cells that can continue to produce blood. But the hematopoietic ability is limited, loss of too much blood at one blow may threaten the life."

"Don't worry. Generally, nosebleeds or superficial wounds barely cause a great amount of blood loss. On average, about 7% of our body weight is blood. If there isn't enough blood, our body will produce by itself."

Daniel felt relieved and turned to leave. And suddenly he thought of something and asked, "How long will it take?"

Mom asked him what the blood was made of. Daniel thought for a while and said, "It's mostly made of water and something red."

Hearing this over simple answer, mom said seriously, "Too rough. Generally, blood is made up of plasma and blood cells. Blood cells include red blood cells, white blood cells and platelets. Plasma makes up about 55% of the body's total blood volume. It is a yellowish liquid and consists mostly of water and plasma protein and other substances. Red blood cells account for about 40% of the total blood volume. Hemoglobin is a special protein in red blood cells that carries oxygen from the lungs to all parts of our body and carries CO₂ out from our body. White blood cells and platelets account for a small percentage of whole blood volume. But they are also vital to our body. White blood cells, like gallant soldiers, can find bacteria and viruses that enter our body and destroy them. Without the white blood cells, we have no immunity and are easily infected by bacteria and viruses. Things will be worse if we don't have platelets. Platelets can help our body stop bleeding. Otherwise, a small cut will bleed uncontrollably."

Daniel knew a lot of things that he had not known before. He touched his ear as he usually did.

Mom continued, "All cells in the blood have a certain life span. Red blood cells usually survive for 120 days, and platelets for only 8 to 10 days. So our body produce new platelets continually. There are five types of white blood cells, including lymphocytes that secrete antibodies and white blood cells that kill microbes. Their life depends on their fight with bacteria and viruses. Sometimes they die with the microbes that make us sick to keep us healthy."

Daniel had never known that these cells have such a short life span, and decided to eat something nutritious in the next few days to produce new blood cells as soon as possible.

Author: Huang Jing