Blood Cells in the Human Body
There are three main types of blood cells in the human body. These are the red blood cells, white blood cells and platelets. The red blood cells are also known as erythrocytes,
white blood cells as leukocytes, and platelets as thrombocytes.
Red blood cells are the most common type of blood cell, making up about 45% of the blood cells. Red blood cells are created in bone marrow and then enter the blood stream. They circulate in the blood for about 120 days before they die and are replaced by new red blood cells. The human body produces about 2 million new red blood cells every second. The red blood cells are responsible for carrying oxygen to all organs and cells in the body, and removing carbon dioxide and other wastes. Red blood cells pick up oxygen in the lungs. The oxygen binds with hemoglobin in the red blood cells, giving oxygenated blood its red color.
White blood cells make up about 1% of the blood cells. There are several different types of white blood cells. Each with their own role to play in the body. The white blood cells are created in bone marrow from stem cells. They then enter the blood circulatory system and lymphatic system. White blood cells are part of the immune system and are responsible for fighting off disease.
Platelets make up the remaining, almost 50% of the blood cells. As with red and white blood cells, platelets are created in bone marrow. They are involved in blood coagulation for healing, and repair and regeneration of connective tissues.
Although there are many different types of cells, they all have a common structure. Each cell is surrounded by a membrane, something like an outer skin. At the center of the cell is the nucleus that provides the cental control for the cell, and contains its genes. Also inside the cell are many different types of organelles each responsible for a specific function. Mitocondria are organelles that supply energy to the cell. Ribosomes are organelles that make cell building proteins. Lysosome organelles break down nutrients, toxins and worn out organelles. The nucleus and organelles are held in cytoplasm, the fluid part of the cell. The golgi body hold products ready to be removed from the cell. Together, they form the building blocks of the human body.