The infographic below provides an overview of the composition of blood and how it is made.
Blood makes up 7% of a person’s weight and is crucial for transporting oxygen and nutrients to cells, removing waste products from cells, contracting muscles, protecting against disease as well as many other functions.
Clean ERSJ has some more information about what is there in our blood.
It’s made up of four main components: red blood cells (45%), platelets (10%), white blood cells (35%) and plasma (the pale yellow liquid which is mostly water).
The red cells carry oxygen through your body; they make up about 45% of the total volume in blood and are responsible for giving it its red color.
Platelets help with clotting; they also exist in relatively low numbers at around 10%.
Here are some points about what is there in our blood-
1. The amount of blood in your body is about 5-6 litres (15-16 pints).
Human beings are made up of around 20 trillion cells; each of these cells needs enough oxygen to live. A single cell responds to this demand by generating red blood cells.
The process of making red blood cells is called erythropoiesis, and it occurs mainly in the bone marrow (bones where blood is formed), which can hold up to 10% of your whole body’s total volume.
After this initial step, the red cells move through the circulatory system, where they change into what are known as erythrocytes (remember that word).
2. A human red blood cell can live for about four months.
Red blood cells lose a little mass every time they bump into membranes of the capillaries and their outer ‘envelope’ is slightly modified each time.
Red cells are recycled after just four months, which is why new ones are constantly being made in the marrow.
This folding and modification process is carried out by a specific enzyme system which uses iron for its activity. The amount of iron in your body ranges from 3 grams to 5 grams; you need approximately 0.02 milligrams per day, and it can be found in foods such as red meat, pulses and beans, green leafy vegetables and whole grains (especially wheatgerm).
3. Blood is like a super pressure cooker.
Blood conducts heat by means of concentrating the blood and plasma at the point where it meets the skin; this is called convection and it has to do with convection currents (like those in a pan of water when one side is heated, and also like those in a boiler).
4. The body needs up to 6 litres of blood for survival.
Brain cells are only made up of 1% of your body’s cells, so they require more oxygen than other areas.
Since they are usually smaller in size, they need less blood to generate an adequate supply of oxygen which allows them to function properly.
The amount of red cells in the whole body is approximately 0.5% of the total volume, and this figure is only enough to keep the body protected from infection and disease for 48 hours.
The fact that blood cells can only survive for about four months means that we must make new ones every three months; we can’t use old ones as they would be destroyed by bacteria.
This fluid has many other important and vital tasks which you cannot see (such as circulating waste products around the body) and maintaining healthy veins during life to prevent heart conditions such as aneurysms or an abnormal buildup of pressure inside a vein which can cause a stroke or hemorrhage.
5. The body has six different types of blood.
Each type has a specific function and purpose. The first is called plasma, which accounts for about 55-60% of the blood’s entire volume.
It plays an important role in transporting nutrients, minerals and dissolved substances around the body as well as playing a vital role in immune defense as it contains antigens, antibodies and memory cells.
Another vital element of blood is platelets; they stick together to form clots to prevent excessive bleeding from wounds.
In addition, some white blood cells are there to fight off germs by producing proteins which can be used to identify foreign particles so they can be destroyed if necessary.
These types of white cells include neutrophils, monocytes and lymphocytes. Lymph is produced in the spleen; it is an ultrafiltrate which is similar to plasma (it contains plasma proteins, glucose and also forms of antibodies).
6. Blood circulation requires strong heart muscles.
The heart is made up of special muscle tissue which is necessary to pump blood around the body; this muscle tissue needs to be supported by a thick membrane (which supports it like scaffolding) for this reason.
The muscles of the heart are also very elastic; they are made up of ‘myofibrils’ which have a spiral shape and have an ability to contract quickly.
