Answer:
Blood is a colloid which mainly contains red and white blood-cells, lymphocytes and plasma.
Explanation:
Believe it or not but blood is considered an organ. That’s because it contains a collection of different types of cells suspended in a liquid, the plasma.
The most obvious type of cell is the red blood cell (erythrocytes), which provides the red color to the blood and more importantly contains haemoglobin, an iron holding protein that binds oxygen or carbon dioxide. This way these gases are transported throughout the body. Oxygen towards the tissues, carbon dioxide outward of course.
Another very important blood cell type are the white ones (leukocytes). Without going into much detail (a lot of different subtypes exist) the white blood cells are responsible for one’s immunity. Some of these cells called macrophages like to swallow stuff that’s not supposed to be in your blood.
A third important type of cell, the smallest ones, are the trombocytes or platelets. The make sure you blood coagulates when you are wounded. Without them you would bleed to death.
Besides these cells a lot of different molecules or ions are dissolved or suspended in the plasma : proteins of which a lot of albumin, vitamins, minerals. The steady bloodstream makes sure every cell in your body is provided with the nutrients it needs.
