The Circulatory System Blood Components: Blood Components The Circulatory System Blood Components Components of Blood: Components of Blood Plasma: The liquid component of blood. This is a straw colored liquid that is mostly water. It makes up about 60% of blood volume. Dissolved within the plasma are metabolites and wastes which can include glucose sugar, proteins, carbohydrates and vitamins. Hormones and gasses can also be found dissolved in plasma. Plasma: Plasma Salts of various types are also dissolved in plasma as ions. The chief constituents are sodium, chloride, and bicarbonate. These ions help maintain the osmotic balance of plasma and keep it from leaking out the capillaries. Proteins are the most abundant solute in plasma. These also maintain the osmotic balance between the cell cytoplasm and the blood. Water does not move from plasma to the cells because the amount of solute dissolved in the plasma prevents osmosis. Blood Cells and Fragments: Blood Cells and Fragments About 40% of blood by volume is blood cells and fragments of cells suspended in the plasma. Red Blood Cells: Non-nucleated bi-concave disks that carry oxygen. RBC are the most common components of blood cells. Each milliliter of blood contains 5 million red blood cells, also called erythrocytes. Most of the cell interior is packed with hemoglobin. This is a pigment that contains iron. It binds with oxygen in the lungs and then releases it to the cells when the blood cell enters a capillary. A shortage of red blood cells is called anemia. Bi-concave, non-nucleated disks filled with hemoglobin that carry oxygen to the cells of the body. White Blood Cells: White Blood Cells There are only 1 or 2 White Blood Cells for every 1000 Red Blood Cells. They are also called leukocytes. The White Blood Cell’s primary job is defending the body against disease. These cells have a nucleus. There are several different types of White Blood Cells. Some take in and digest harmful organisms while others produce antibodies to mark various particles and organisms for destruction by other cells. White Blood Cells are nucleated and have an amoeboid shape. They also move indep - endently via pseudopods to find and destroy body invaders like bacteria and viruses. Platelets: Platelets In certain large cells in bone marrow, bits of cytoplasm are regularly pinched off. The fragments are called platelets. They are not proper cells. They play an important role in blood clotting. When a hole is detected in the body, platelets arrive via the blood stream. They assume an irregular shape and generate a substance that allows them to become very sticky. They attach to the protein fibers of the cell walls and eventually form a sticky patch the plugs the hole. Platelets are not nucleated because they are not cells. They are produced in Red Bone Marrow as are blood cells. Blood Clot Formation: Blood Clot Formation The Mechanism for blood clotting is as follows: 1. Blood vessel damage is the stimulus that sets this mechanism into motion. It is detected. 2. Platelets congregate in the area and begin releasing clotting protein (enzyme). 3. A reaction within the platelets allows them to become irregularly shaped and sticky. 4. A Chemical reaction occurs among the platelets that produces a sticky protein fiber called a fibrin net that catches more red blood cells and platelets and uses them to plug the hole. Blood Type: Blood Type There are several different blood types among humans. Blood type is based on marker molecules found on the surface of red blood cells. People with different marker molecules can not share blood because the body’s immune system recognizes the foreign markers and attacks the strange blood cells as though they were an infection. The most common way to type blood is the ABO Blood Group System. Under this system there are 4 types of blood. These are A, B, AB, and O. The letters refer to complex carbohydrate markers found on the blood cell’s surface. People with type A blood have type A antigens on their RBCs. People with type B blood have type B antigens. People with type AB blood have both types of antigens, and people with type O blood have no antigens. Blood Donors: Blood Donors People who are running short of blood can receive it by means of a transfusion from people with compatible blood types. Type A people can receive from Type A and Type O donors. They can donate to Type A or Type AB. Type B people can receive from Type B and Type O donors. They can receive from Type B or Type AB. People with Type AB blood can receive blood only blood from anyone but can only donate to Type AB. Finally, people who are Type O can receive blood only from Type O people but can donate blood to anyone. Type O is considered the universal donor. Anyone can use it.