Composition of Blood

Composition of Blood

• Blood is a complex connective tissue composed of formed elements (cells and cell fragments) suspended in a fluid matrix called plasma.
• Plasma, the liquid portion, accounts for about 55% of blood volume and is primarily water.
• Dissolved substances in plasma include proteins (albumin, globulins, fibrinogen), nutrients, electrolytes, hormones, gases (oxygen, carbon dioxide), and waste products.
• Formed elements include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
• Red blood cells are responsible for oxygen transport, while white blood cells fight infection, and platelets help stop bleeding.

Erythrocytes (Red Blood Cells)

• Erythrocytes are biconcave discs that lack a nucleus and mitochondria, maximizing their surface area for gas exchange.
• They contain hemoglobin, a protein that binds oxygen and carries it throughout the body.
• Hemoglobin gives blood its red color.
• Erythrocytes have a lifespan of approximately 120 days.
• New red blood cells are constantly produced in the bone marrow to replace old and damaged ones.

Leukocytes (White Blood Cells)

• Leukocytes are crucial components of the immune system.
• They are responsible for defending the body against infections and foreign invaders.
• Leukocytes are categorized into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
• Granulocytes have granules in their cytoplasm, while agranulocytes do not.
• Each type of white blood cell plays a specific role in immunity and inflammation.

Thrombocytes (Platelets)

• Platelets are cell fragments that play a vital role in blood clotting.
• They help prevent blood loss from damaged blood vessels.
• Platelets release clotting factors and proteins that form a fibrous network to stop bleeding at a site of injury.
• The process involves a cascade of chemical reactions.

Blood Types

• Blood is categorized into different types based on the presence or absence of certain antigens on the surface of red blood cells.
• The most common blood typing system is the ABO system, which categorizes blood into A, B, AB, and O types.
• Incompatible blood transfusions can lead to serious complications.
• The Rh factor is another important blood group system classifying blood as Rh positive or Rh negative, influenced by the presence or absence of the Rh antigen.

Blood Functions

• Transporting oxygen and nutrients to tissues and removing waste products.
• Regulating body temperature and pH.
• Protecting the body from pathogens and foreign substances through the immune system.
• Clotting to prevent blood loss.
• Maintaining homeostasis by transporting hormones and other signaling molecules.

Blood Disorders

• Anemia is a condition characterized by a deficiency of red blood cells or hemoglobin.
• Leukemia is a type of cancer that affects white blood cells, characterized by uncontrolled proliferation of abnormal white blood cells.
• Thrombocytopenia is a condition in which the number of platelets is too low.
• Hemophilia is an inherited disorder that impairs the blood's ability to clot.

Blood Circulation

• Blood circulates throughout the body in a closed system of blood vessels (arteries, veins, and capillaries), driven by the pumping action of the heart.
• Arteries carry oxygenated blood away from the heart, whereas veins carry deoxygenated blood back to the heart.
• Capillaries are the smallest blood vessels where gas and nutrient exchange occurs between the blood and surrounding tissues.