Blood is a specialized body fluid that circulates through the entire body and has many different functions, including transporting oxygen and nutrients to cells, removing waste products, and fighting infections. Blood has four main components: plasma, red blood cells, white blood cells, and platelets.

• Plasma: This is the liquid component of blood, which makes up about 55% of whole blood. It is a mixture of water, sugar, fat, protein, and salts, and its main job is to transport blood cells throughout the body along with nutrients, waste products, antibodies, clotting proteins, chemical messengers such as hormones, and proteins that help maintain the bodys fluid balance.

• Red Blood Cells: Also known as erythrocytes or RBCs, these are the most abundant cells in the blood, accounting for about 40 to 45 percent of its volume. They are responsible for carrying oxygen from the lungs to the rest of the body and then returning carbon dioxide from the body to the lungs so it can be exhaled. Red blood cells contain a special protein called hemoglobin, which gives them their bright red color and helps them carry oxygen.

• White Blood Cells: Also known as leukocytes, these cells are fewer in number than red blood cells, with a ratio of about 1 white blood cell to every 600 to 700 red blood cells. They are responsible primarily for defending the body against infection and are an important part of the immune system[[2]](https://www.redcrossblood....