When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.

Low-density lipoprotein (LDL) cholesterol are considered to be "bad cholesterol" because it transports fat molecules to arteries and attracts macrophages, leading to atherosclerosis. Alternatively, high-density lipoprotein (HDL) cholesterol is considered to be "good cholesterol" because it removes fat molecules from macrophages, decreasing the risk of atherosclerosis.

Coagulation Factor II (prothrombin) is a protein produced in the liver. Prothrombin is modified after translation to produce thrombin. Thrombin is an enzyme that catalyzes coagulation reactions and results in reduced blood loss. Factor II deficiency is an autosomal recessive mutation that can result in defects in blood clotting.

The buffy coat is so-named because it has the majority of white (immune) cellular material, while the hematocrit contains most of the red cell material (hemoglobin), and the plasma has the fluid and circulating proteins, such as antibodies.

Erythrocytes are found in the hematocrit, lymphocytes are found in the buffy coat, and clotting factors, albumin, and fluids are found in the plasma.

Albumin is the protein that is involved in transporting a variety of products throughout the blood as well as the protein factors involved in blood clotting. Albumin makes up about 50% of the plasma protein distribution. It is responsible for binding insoluble molecules to transport them through the aqueous blood stream. Albumin is also the main driver of oncotic pressure in the arteries and veins to keep water from moving to the tissues via osmosis.

Plasminogen, thrombin, and thromboxane are all proteins involved in the clotting process and are also found in the blood.

Fibrinogen is converted to fibrin by the action of thrombin, and fibrin is the protein that actually forms a blood clot. An inability to properly form clots, such as is seen in hemophilia, could arise from a defect in fibrinogen, resulting in a problem with the clotting pathway.

Renin is an enzyme released by the kidney, which creates angiotensin to help raise blood pressure. Vasopressin is a posterior pituitary hormone that acts on the kidney to retain water. Albumin is a plasma protein that functions to maintain the oncotic pressure in the blood, as well as to transport fatty acids. Major histocompatibility complex (MHC) proteins are used to present antigens to the immune system.

The plasma portion of the blood is the extracellular matrix that suspends the erythrocytes and lymphocytes traveling through circulation. The plasma contains water, proteins (chiefly albumin), electrolytes, and clotting factors (such as thrombin). Whole blood contains the cells, as well as thx extracellular plasma. Blood serum refers to blood plasma that has had the clotting factors removed.

Mature erythrocytes (red blood cells) do not contain a nucleus and lack most organelles. While immature, the erythrocyte contains a nucleus, but this gets extruded in order to make more room for hemoglobin to transport oxygen. It is important to understand the implications of not having any additional organelles; the red blood cell cannot derive energy from the citric acid cycle and cannot produce, transport, or exocytose proteins. This may seem like a problem, but it actually prevents the red blood cell from consuming the oxygen that it is transporting. If erythrocytes contained nuclei or mitochondria, they would metabolize the oxygen attached to hemoglobin, failing to deliver it to other tissues.

The mature erythrocyte (red blood cell) contains no nucleus, mitochondria, Golgi apparatus, or endoplasmic reticulum. Consequently, the red blood cell can only derive energy from glycolysis, the anaerobic breakdown of glucose in the cytosol. Mitochondria would be required for any other metabolic process.

Thrombin, created from prothrombin after activation by coagulation factors from the liver, is responsible for turning fibrinogen to fibrin. Fibrin adheres to endothelial cells and platelets to allow clots to form in response to vessel damage. Complement helps attract immune cells to the site of injury. Platelet monoamine oxidase degrades amines, such as serotonin, in neuronal synapses.