Leukocytes: The Body's Defenders

Cardiovascular Disease and Coagulation

• Omega-3 fatty acids can decrease coagulation and are often recommended to treat cardiovascular disease.

Blood Types

• Blood type is classified based on the presence of A antigen, B antigen, both A and B antigens, or no antigen on the surface of erythrocytes.
• Type O blood has anti-A and anti-B antibodies already preformed in the body.

Blood Transfusions

• Type O blood is the best match for an emergency blood transfusion if the recipient's blood type is unknown.

Blood Composition

• Erythrocytes (red blood cells) make up approximately 45% of blood.

Immune System

• The immune system is responsible for protecting the body from external and internal threats like bacteria and viruses.
• White blood cells (leukocytes) play a key role in the immune system.

Blood Circulation and Temperature

• When the body is hot, blood circulates more to the skin to aid in cooling.
• Blood is a little warmer than normal body temperature due to the heat generated from metabolic processes.

Erythrocytes

• The main function of erythrocytes is to transport oxygen from the lungs to the body tissues.

Blood Clotting

• The protein fibrin is important for clotting.
• The intrinsic pathway of coagulation is activated when the blood vessel wall is damaged.
• The extrinsic pathway of coagulation is activated when tissue factor is released from damaged tissues.

Hemopoiesis

• Hemopoietic growth factor stimulates the production of blood cells.
• Cytokines play a key role in regulating hemopoiesis.
• Hemopoiesis occurs in the bone marrow.

Leukocytes

• Lymphocytes lead to immunity from disease.
• Neutrophils are quick responders and attack bacteria well.
• Eosinophils play a role in combating parasites and in allergic reactions.
• Basophils release histamine and heparin, which opposes blood clotting.

Anemia and Polycythemia

• Sickle cell anemia is caused by a genetic mutation in hemoglobin.
• Pernicious anemia is caused by insufficient absorption of B12 or folate.
• Polycythemia can be caused by an overproduction of erythrocytes.

Hemostasis

• Platelets play a key role in hemostasis by forming a platelet plug and releasing chemicals that attract more platelets.
• Thrombosis occurs when a thrombus (blood clot) forms in a blood vessel.
• If a thrombus breaks free and floats in the blood vessels, it can cause an embolism.
• The main function of platelets is to form a platelet plug and release chemicals that attract more platelets.

Immune System Cells

• B cells play a key role in immunity by producing antibodies.
• T cells play a key role in the immune system by directly attacking infected cells.
• Leukemia is a condition characterized by an overproduction of leukocytes that may not be able to mature or function properly.

Test your knowledge about leukocytes, the white blood cells that protect the body and play a vital role in the immune system. Learn about their characteristics, functions, and behavior in the body.