What makes up 45 of blood

Blood also transports waste substances to the kidneys and liver, which remove them and process them for elimination. Blood regulates body temperature. When the body needs to warm up or cool down, the circulatory system plays an important role. This is called vasodilation. Blood protects the body from pathogens. Some white blood cells are specialized to engulf bacteria and other pathogens through a process called phagocytosis.

Blood clots to prevent blood loss at sites of injury. When a blood vessel tears, platelets in the area activate, connecting with other platelets to form a plug to prevent further blood loss. These platelets release enzymes that help a blood clot form. Blood cells are produced within red bone marrow. There are five types of white blood cells: neutrophils, basophils, eosinophils, monocytes, and lymphocytes. Visible Body Biology Learn more.

External Sources An article from the Leukaemia Foundation describing blood formation. Get our awesome anatomy emails! Erythrocytes are transfused to compensate for blood lost during operations or childbirth, in neonatal intensive care and to treat anaemia. A donation of ml of whole blood can yield one erythrocyte suspension for an adult or, in the case of young children, several doses of red blood cells.

Instead, red blood cells acquire energy through metabolic processes that do not require oxygen. The lack of nuclei and mitochondria therefore allow the red blood cell to function without depleting its cargo of oxygen, leaving more oxygen for the body tissues.

The molecule that binds oxygen in red blood cells is called hemoglobin. Hemoglobin is a large, globular protein consisting of four protein chains surrounding an iron core. Hemoglobin is densely packed inside the red blood cell; in fact, hemoglobin accounts for a third of the weight of the entire red blood cell.

Each red blood cell contains about molecules of hemoglobin. In the lungs, oxygen diffuses across the red blood cell membrane and binds to hemoglobin. As blood circulates to the tissues, oxygen diffuses out of the red blood cells and enters tissues.

The waste product of aerobic metabolism, carbon dioxide, then diffuses across red blood cells and binds to hemoglobin. Once circulated back to the lungs, the red blood cells discharge their load of carbon dioxide, which is then breathed out of the lungs. The complexity of blood is apparent.

Still, researchers hope to create synthetic blood substitutes, which will ease the burden of dwindling donations to meet the demand for surgeries, transfusions, and emergency use. Currently under development is an artificial blood that uses perfluorocarbons to carry oxygen to tissues, replacing the function of hemoglobin. Perfluorocarbons are long, fatty hydrocarbon chains containing fluorine that have the ability to pick up oxygen in lungs, and release it into tissues. The artificial blood made with these molecules is a mixture of the perfluorocarbons with saline physiological salt water using surfactants, substances that allow the mixing of oil and water.

The solution then can be administered to patients. Over time , as the artificial blood helps deliver oxygen to tissues, the perflourocarbon molecules are exhaled from the body. Strictly, this substance is not a whole blood substitute since it only has the ability to carry oxygen and cannot replace the other important functions of blood. However, it is valuable because it eliminates the risk of transmitting disease during transfusions as well as preventing accidental blood type mismatches.

Sickle cell anemia is an inherited disorder caused by a defect in one of hemoglobin's four protein chains. The sickle hemoglobin distorts the shape of the red blood cells and injures the red blood cell membrane. Water and potassium leak from the cells, causing the red blood cells to become "sickle-shaped. As a result of these changes, oxygen transport is severely interrupted and circulation of the blood through the blood vessels can become blocked.

These irregular blood cells do not carry as much oxygen as their normally-shaped counterparts. Sickle cell anemia is invariably fatal; most people with the disease die in early adulthood. Red blood cells are formed in red bone marrow from precursor cells called pluripotent stem cells. The process of red blood cell formation is called hemopoiesis, or hematopoiesis. In adults, hemopoiesis takes place in the marrow of ribs, vertebrae, breast bone, and pelvis. On average, a red blood cell lives only months.

Constant wear and tear on the red blood cell membrane, caused by squeezing through tiny capillaries, contribute to the red blood cell's short life span. Worn out red blood cells are destroyed by phagocytic cells cells that engulf and digest other cells in the liver.

Parts of red blood cells are recycled for use in other red blood cells, such as the iron component of hemoglobin. An interesting aspect of red blood cells is that they carry certain proteins, called antigens, on their plasma membranes. A person with A antigens is type A; a person with B antigens is type B; a person with both antigens is type AB; and a person with none of the antigens is type O.

A individuals have antibodies to B antigens; B individuals have antibodies to A antigens; AB individuals do not have antibodies to the antigens, and O individuals have antibodies to both A and B antigens. These combinations are necessary to know for blood transfusions. For instance, if a type A individual donates blood to a type B individual, the A antibodies in the recipient's B blood will react with the A antigens of the donor's A blood.

This reaction, called the agglutination reaction, causes the blood cells to clump together. Agglutination can be fatal. Until blood typing was worked out early in this century, many deaths from blood transfusions occurred due to incompatibility of antigens and antibodies.

White blood cells are less numerous than red blood cells in the human body; each microliter of blood contains 5,, white blood cells.

The number of white blood cells increases, however, when the body is fighting off infection. White blood cells, therefore, are maintained at a stable number until the immune system detects the presence of a foreign invader. Neutrophils, the most numerous leukocytes, are phagocytic and have light-colored granules. Eosinophils have granules and help counteract the effects of histamine. Basophils secrete histomine and heparin and have blue granules.

In the tissues, they are called mast cells. Lymphocytes are agranulocytes that have a special role in immune processes. Some attack bacteria directly; others produce antibodies. Thrombocytes, or platelets, are not complete cells, but are small fragments of very large cells called megakaryocytes. Megakaryocytes develop from hemocytoblasts in the red bone marrow.