Why Is Blood Percentage Important for Your Health and Studies?
The volume of blood in an individual’s body vary from one individual to another. There are lots of factors upon which the blood percentage in the human body depends. Age and size are the two main factors.
The total volume of blood in the human body in litres normally ranges from 4.5 to 5.7 liters. The average blood percentage in the human body is approximately 7 per cent of the body weight. In this article, we’ll discuss the quantity and normal blood percentage in the human body, along with shocks and blood loss.
Average Blood in Human Body in Liters
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The total blood volume is different in the case of infants, children, and adults. Pregnant women have a different blood percentage in the human body when compared to normal adults. In this part, we will look into total blood in the human body in liters in detail. We will be discussing blood volume. As stated above, the normal blood percentage in the human body is about 7 percent of the body weight.
Infants or babies have approximately 75ml of blood per kilogram of their body weight. So if an infant weighs around 8 pounds, he/she will have approximately 270 ml of blood. An average child weighs around 80 pounds. The blood volume in the child’s body is supposed to be around 2.65 liters of blood. For an average adult, the quantity of blood in the human body in litres is estimated to be around 4.5 to 5.7 litres. Pregnant women have a considerable high blood volume to support the growing baby. It's about 30 to 50 percent greater than a normal adult female. It can be seen that the total blood volume varies with age, sex, and body weight.
Blood Volume Test
This is a test used to determine the volume of blood in the human body in litres and track the movement of the blood cells. It generally tests the blood volume in a human body. In this test, a small tracer element is injected into the bloodstream. The medical professional uses various imaging techniques to trace the movements of the blood cells and measure the average blood in the human body in litres. This test is often recommended by the doctors if the patient shows congestive heart or kidney failure or shocks.
Blood Loss and Shock
The term ‘“shock” can be used to denote a medical condition where sufficient oxygen does not reach every part of the body. Severe states of shock can prove to be quite fatal. Nominal blood loss may not be much of a harm. However, after losing 20-40 percent of the total blood volume, the person will start to feel anxious. The blood pressure will rise rapidly. When the blood loss exceeds the 40 percent mark, the person will feel lethargic and lose consciousness. The person will also experience severe shocks during this time. Blood loss may be due to internal or external bleeding.
The quantity of blood in the human body in litres is around 4.5 litres in the case of an adult. So one can donate up to one pint of blood. As a huge volume of blood is produced, the body can easily replace a small amount of lost or donated blood.
Maintenance and Production of Blood
The human body produces around 2 million red blood cells per second from the stem cells in the bone marrow. These stem cells produce RBCs and maintain the normal blood percentage in the human body. Apart from the RBCs, the white blood cells (WBCs) act as a defence mechanism of the body and platelets. The circulation and purification of the blood are carried out by the various cardiovascular systems. Plasma is an important component of the blood as it carries the RBCs, platelets and boosts the immune system.
Interesting Facts about Total Blood Volume in the Human Body
An adult body has 1,00,000 kilometres or 60,000 miles of blood vessels running throughout the body.
Blood plasma makes up around 55% of the total volume of blood present in the human body.
The average volume of blood present in an adult male body is 5.6 litres, while an adult female body contains 4.5 litres of blood.
FAQs on Blood Percentage in Human Body: Explained for Students
1. What is the normal percentage of blood in the human body?
On average, blood accounts for about 7% to 8% of a person's total body weight. This is an estimate and the exact volume can vary based on factors like age, sex, and overall health. For example, an adult weighing 70 kg would have approximately 4.9 to 5.6 litres of blood.
2. How much blood does an average adult have in litres?
An average adult typically has between 4.5 and 5.7 litres of blood. Generally, adult males have slightly more blood volume (5-6 litres) than adult females (4-5 litres) due to differences in average body size and composition.
3. How can I estimate the blood volume in my body?
You can get a rough estimate of your blood volume using a simple calculation. Since blood is about 7% of body weight, you can multiply your weight in kilograms by 0.07. For example, if a person weighs 60 kg, their estimated blood volume would be 60 kg × 0.07 = 4.2 litres.
4. Why does blood volume vary between infants, adults, and pregnant women?
Blood volume varies significantly due to different physiological needs:
- Infants: Have a higher blood volume relative to their body weight (about 75 ml per kg) to support rapid growth and a higher metabolic rate.
- Adults: Have a stable volume based on their body mass, which supports normal bodily functions.
- Pregnant Women: Experience a significant increase in blood volume, up to 30-50% more than usual. This extra blood is necessary to supply oxygen and nutrients to the developing fetus and the placenta.
5. What is the difference between blood volume as a percentage of body weight and the hematocrit level?
These two measurements describe different aspects of blood. Blood volume refers to the total amount of blood (plasma and cells) in the body. In contrast, hematocrit (also known as Packed Cell Volume or PCV) is the percentage of the blood volume that is occupied by red blood cells. A high hematocrit means a higher concentration of red blood cells, which is crucial for oxygen transport.
6. What happens to the body when a significant amount of blood is lost?
Losing a significant amount of blood can lead to a condition called hypovolemic shock, where the heart cannot pump enough blood to the body. If blood loss exceeds 20% of the total volume, a person may experience anxiety, rapid heart rate, and a drop in blood pressure. If it exceeds 40%, the situation becomes life-threatening, often leading to loss of consciousness and organ failure due to lack of oxygen.
7. Is it possible to have too much blood, and what are the implications?
Yes, it is possible to have an abnormally high concentration of red blood cells, a condition known as polycythemia. This increases the total blood volume and, more importantly, its viscosity (thickness). Thick blood flows more slowly through vessels and increases the risk of developing blood clots, which can lead to serious complications like a stroke or heart attack.
8. How does the body's total blood volume allow for a safe blood donation?
The body can safely handle the loss of blood during a donation because the amount taken (typically one pint or about 470 ml) represents only about 10% of the average adult's total blood volume. The body's homeostatic mechanisms are highly efficient at replacing the donated blood. The plasma volume is restored within 24 hours, and the red blood cells are replenished over the next few weeks.
