About blood
Blood forms the transport system of our body. It flows continuously to deliver oxygen and nutritional substances and to remove waste products. Blood is liquid and reaches all parts of the body through the blood vessels. It also plays an important role in defending against pathogens in the body and helps maintain a constant body temperature.
How much blood does a human have?
The amount of blood in the human body is about 7% of body weight, and roughly half of that is water. On average, an adult woman has 4.5 liters of blood, and an adult man has 5.6 liters of blood in the body.
This blood is pumped around by the heart through a system of arteries, veins, and capillaries—also known as the circulatory system.
Composition of blood
The liver regulates the composition of the blood. In this chemical factory, the liver ensures that the blood contains the substances the body needs. It also breaks down toxins in the blood, such as medications and alcohol.
Your blood consists of about half plasma. Blood plasma is mainly made up of fluid and proteins. The other half of your blood consists of blood cells, namely: red blood cells, white blood cells, and platelets
Functions of blood
The blood in your body acts like central heating, helping to maintain a constant body temperature and pH level (also known as acidity). The various components of blood each have their own specific function.
- Red blood cells transport oxygen and carbon dioxide throughout your body.
- White blood cells identify and neutralize harmful substances and pathogens.
- Platelets are responsible for forming scabs when you have a wound.
Finally, plasma carries nutrients from your small intestine to tissues and organs, and transports urea from the liver to the kidneys. It also helps distribute hormones throughout your body.
Color of blood
The color of our blood is determined by hemoglobin. Oxygen-rich blood is bright red, while oxygen-poor blood is dark red. So, the color of your blood isn’t the same throughout your body. Blood in veins flows beneath several layers of tissue, which makes it appear darker. That’s why veins don’t look red, but sometimes blue. This is where the term “blue blood” comes from.
Can you miss blood?
Blood is very important for our body, but we can spare a little of it. Fortunately, the body produces new blood and recovers over time.
During a blood donation, you give 500 ml of blood. To allow proper recovery, there must be at least 56 days (8 weeks) between two donations for men; for women, it’s 122 days (4 months). This is because the recovery time after a blood donation is longer for women.