11.1-11.4

Blood Functions

Blood serves five major functions including transporting dissolved gases, nutrients, hormones, and metabolic wastes; regulating the pH and ion composition of interstitial fluids; restricting fluid losses at injury sites; defending against toxins and pathogens; and stabilizing body temperature.

Composition of Whole Blood

Whole blood consists of plasma and formed elements, which include blood cells and cell fragments.

Venipuncture

Venipuncture is a common technique for obtaining a blood sample due to the ease of locating superficial veins, thinner vein walls compared to arteries, and relatively low blood pressure in the venous system.

Plasma Proteins

Plasma contains three major types of proteins - albumins, globulins, and fibrinogen, which make up more than 99% of the plasma proteins.

Red Blood Cells (RBCs)

Red blood cells, formed by erythropoiesis, are the most abundant blood cells, containing hemoglobin that binds and transports oxygen and carbon dioxide.

Plasma Proteins

Proteins in solution in the bloodstream, synthesized mainly by the liver, including albumins, globulins, fibrinogen, and prohormones.

Albumins

Constitute about 60% of plasma proteins, major contributors to the osmotic pressure of plasma.

Globulins

Account for approximately 35% of plasma proteins, including antibodies and transport globulins.

Fibrinogen

Functions in clotting, forming insoluble strands of fibrin for blood clotting.

Organic Nutrients

Include lipids, carbohydrates, amino acids, and vitamins, used for ATP production and cell maintenance.

Electrolytes

Essential for vital cellular activities, major plasma electrolytes include Na+, K+, Ca2+, Mg2+, Cr, HCO3, HPO4, and SO42-.

Organic Wastes

Include urea, uric acid, creatinine, bilirubin, and ammonium ions, carried for breakdown or excretion.

Platelets

Small cell fragments important for clotting, containing enzymes and substances for clot formation.

White Blood Cells

Leukocytes participating in the body's defense mechanisms, including neutrophils, basophils, lymphocytes, eosinophils, and monocytes.

Red Blood Cells

Erythrocytes, the most abundant blood cells, essential for oxygen transport in the blood.

Jaundice

A condition characterized by yellow skin and eyes due to an accumulation of bilirubin in the body.

Urobilins and stercobilins

Pigment molecules derived from bilirubin that contribute to the yellow color of urine and the brown color of feces.

Transferrin

A plasma transport protein that binds to iron in the bloodstream for delivery to developing red blood cells in the bone marrow.

Erythropoiesis

The process of red blood cell formation that occurs in the red bone marrow.

Hemoglobin

The protein inside red blood cells responsible for transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs.

Erythropoietin (EPO)

A hormone that stimulates red blood cell production in response to low oxygen levels in tissues.

Blood types

Determined by the presence or absence of specific surface antigens (A, B, Rh) on red blood cells, leading to classification into types A, B, AB, or O.

Rh factor

Refers to the presence or absence of the Rh antigen on the surface of red blood cells, influencing blood type categorization as Rh positive or Rh negative.

Antigens

Substances, often proteins, that can trigger an immune response; RBCs contain surface antigens that determine blood type.

Agglutinogens

Surface antigens on RBCs that are ignored by the immune system of the individual.

Agglutinins

Antibodies present in plasma that attack surface antigens on RBCs of a different blood type.

Cross-reaction

Interaction between antibodies in the recipient's plasma and antigens on donated RBCs, leading to agglutination and potential hemolysis.

Agglutination

The clumping together of foreign RBCs due to the binding of antigens and antibodies.

Hemolysis

The breakdown of RBCs, often occurring after agglutination, leading to the release of clumps and fragments that can block small vessels.

Hemolytic Disease of the Newborn

A potentially fatal condition where maternal antibodies attack and destroy fetal RBCs, often due to Rh incompatibility.

Blood Compatibility Testing

Involves determining blood type and conducting a cross-match test to ensure compatibility between donor and recipient blood.

Universal Donors

Type O individuals, especially O-, who can safely donate blood to recipients of any blood type due to the lack of A and B surface antigens.

Universal Recipients

Type AB individuals who can receive blood from any blood type due to the absence of anti-A or anti-B antibodies.

Cross-match Testing

Exposing the donor's RBCs to the recipient's plasma to check for significant cross-reactions involving other antigens and antibodies.