Hematology is the study of blood and the treatment and prevention of diseases affecting this vital fluid. Doctors working in the field manage patients with blood diseases and disorders, either by providing direct care or working in a laboratory, where they analyze smears and slides of blood and bone marrow for diagnoses.


1. Components of Blood

Blood has multiple components, some of the most important being plasma, red blood cells, white blood cells, and platelets.

  • Plasma is the liquid in which all the other components are suspended. The main part of plasma is albumin, a protein that prevents fluid from leaking out of the vessels and into the tissue.
  • Red blood cells make up about 40 percent of the blood. They contain hemoglobin, which creates the red color and delivers oxygen to the body.
  • White blood cells defend against infections. Platelets help with clotting, gathering at the site of injury to clump together, and seal the vessel. Jonathan Knowles / Getty Images


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