Blood Components and Immune Cells: Key Concepts for Hematology

Plasma

Liquid part of blood; carries solutes.

Viscosity

Thickness/resistance to flow.

Osmolarity

Solute concentration in blood.

Erythrocyte

Red blood cell.

Hemoglobin (Hb)

Oxygen-carrying protein in RBCs; gives red color.

Erythropoiesis

Production of red blood cells.

Erythropoietin (EPO)

Hormone from kidneys that stimulates RBC production.

Hematocrit

Percentage of blood volume made of RBCs.

Antigen

Marker on cell surface; determines blood type.

Antibody

Protein that attacks foreign antigens.

Universal Recipient

Type AB blood.

Universal Donor

Type O blood.

Rh Antigen (D antigen)

Determines positive/negative blood type.

Rh Incompatibility

When Rh- mother carries Rh+ fetus → hemolytic disease of newborn.

Leukocyte

White blood cell; fights infection.

Neutrophil

Most abundant WBC; phagocytoses bacteria.

Lymphocyte

Produces antibodies; immune memory.

Monocyte

Becomes macrophage in tissues.

Eosinophil

Fights parasites; involved in allergies.

Basophil

Releases histamine to promote inflammation.

Thrombopoiesis

Formation of platelets.

Hemostasis

Stoppage of bleeding.

Fibrin

Sticky protein that forms framework of a blood clot.

Platelet plug

Temporary seal formed by platelets after vessel injury.

Iron-Deficiency Anemia

Not enough iron; low hemoglobin.

Pernicious Anemia

Lack of intrinsic factor; can't absorb vitamin B12.

Sickle-Cell Anemia

Defective hemoglobin; RBCs become sickle-shaped.

Polycythemia

Too many RBCs; thick blood, clot risk.

Hemorrhagic Anemia

Anemia caused by blood loss.

Hemolytic Anemia

RBCs destroyed faster than replaced.

Most Abundant WBC

Neutrophil.

Function of WBCs

Defense against infection.