What many people are unaware of is that blood is considered a connective tissue. Tissues are defined as groups of cells that work together in order to carry out a designated function in a living organism. Blood consists of red blood cells (erythrocytes), white blood cells (leukocytes), platelets (thrombocytes), and blood plasma. The two types of blood cells and the platelets are suspended in a fluid medium called blood plasma.
The red blood cells contain hemoglobin which is a type of protein that contains iron and functions in transporting oxygen. When the hemoglobin is oxygenated, that is it is transporting oxygen, it provides the red blood cells with their red color. Red blood cells are the most abundant type of cell found in the blood. They are the supply officers on the front lines. They serve in transporting oxygen and small amounts of dissolved carbon dioxide throughout the body. Red Blood cells are circular structures with a slight indent in the middle.
White blood cells serve in seeking out and destroying foreign objects or materials invading the body. They conduct themselves like dedicated commandos attacking any bacteria, viruses, and other invading materials that are considered highly suspect and potentially dangerous to the body's survival. They also aid in waste removal of the remains of deceased cells. Two different groups of white blood cells exist called granular and agranular leukocytes. The majority of white blood cells will consume an invading foreign body via the process known as phagocytosis. In phagocytosis the white blood cells engulf the foreign body and release enzymes known as lysozymes which serve in breaking down the unwanted material in order to prevent any further harmful consequences.
Platelets are not actually cells but rather are fragments of cells that play an essential role in blood clotting. These are the field or combat medics also on the front lines. Clotting of the blood is necessary to stop the leakage of blood through something such as a cut in the skin or a broken blood vessel. Blood clotting involves the process known as coagulation in which solid clots are formed by the blood to stop blood flow out of damaged or injured areas.
Blood plasma, the liquid portion of blood, is involved in helping to transport vital nutrients that have been dissolved in the blood, hormones, enzymes, certain proteins, essential ion, and dissolved gases such as carbon dioxide and oxygen. These are the hearty vehicles that transport the vital supplies and soldiers to the front. When separated out from the other components of blood, blood plasma consists primarily of water, approximately 90%. It takes on a golden-yellow color similar to the color of straw. It is estimated that approximately 55% of our blood actually consists of blood plasma.
Bone marrow is responsible for the production of all the blood cells, including the platelets. This is the training station that doubles as a partial supply warehouse where the soldiers and supplies are stored and trained. Blood vessels serve as tunnels that allow for the constant flow of blood throughout the body. The heart is the central pumping station that aids in lending the blood its momentum, its ability to move throughout the body. It is the command central for the front line troops. Blood circulates into and out of the heart. Arteries carry oxygenated blood away from the heart while veins carry blood containing carbon dioxide back to the heart. Carbon dioxide is then passed to the lungs to be exhaled.
It has been said that blood makes up about 7% of a person's total body weight. On average an adult is estimated to contain five liters of blood in their entire body. The breakdown is as follows: 55% of blood consists of blood plasma; red blood cells constitute 45%; white blood cells are about 1%; and platelets make up less than 1% or basically the remaining portion of the blood. All in all our bodies are very complicated but magnificent machines. Blood aids in carrying the necessary supplies throughout the body to the required destinations to furnish various organs, tissues, and vital systems with the necessary materials they need to function properly. The blood also serves as a soldier for the defense system during times of war and invasion.