Primary Functions of Blood

Primary Functions of Blood

· Hematology refers to the study of blood and its function. While anatomy describes the physical composition of blood and blood cells. Physiology describes how the blood cells and blood function. Blood serves three primary functions: distribution, regulation, and protection.

Distribution, Regulation, and Protection

Distribution refers to blood’s transportation roles as it carries nutrients, oxygen, carbon dioxide, glucose, hormones. And cellular waste throughout the body.

Regulation is part of homeostasis, in which blood helps maintain pH, fluid. And temperature within narrow windows for survival.

Protection includes white blood cell protective functions against foreign cells. And materials, as well as the platelets’ clotting response (called hemostasis) to prevent blood loss.

3-Step Hemostasis Process

When a blood vessel is injured, the 3-step hemostasis process follows:

· Vascular spasm. In this first step, the damaged blood vessel constricts. This is called vasoconstriction.


From Visible Body. (n.d.). Vascular Spasm (Illustration).


· Platelet plug formation. In the second step. Thrombocytes (also known as platelets) stick together to stop the bleed from within the injured vessel.


From Visible Body. (n.d.). Platelet Plug Formation (Illustration).


· Coagulation. In the third and final step, fibrinogen proteins from the plasma. Are converted to fibrin as they act like glue on the platelet plug to seal the injured area.


From Visible Body. (n.d.). Coagulation (Illustration).


The clotting process is dependent on plasma proteins synthesized by the liver, Vitamin K (potassium). And calcium. When a clot is no longer needed, the plasmin enzyme breaks the clot down in a process called fibrinolysis.

Medically, conditions such as a thrombus. Or embolism may require anti-coagulant medications. A thrombus is an unwanted clot that forms without blood vessel damage. This is more common in adults with elevated cholesterol. And diseased blood vessel conditions. If a thrombus or part of a thrombus breaks loose to travel. And lodge in another location away from its origin, it is called an embolism. These embolisms may cause conditions like strokes (cerebrovascular accidents).

Conversely, people may have bleeding disorders which make clotting difficult. Common causes include hereditary disorders like hemophilia, thrombocytopenia (low platelet count). Or impaired liver function.