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Chapter 22

Blood

Chapter 22

Blood

The cardiovascular or circulatory system comprises the blood, the heart, and the blood vessels. Blood is a specialized fluid comprising cells in a liquid …
Approximately 8% of the body mass comprises whole blood, a specialized connective tissue vital for transportation, regulation, and protection. The …
Whole blood consists of the blood plasma, a fluid extracellular matrix, and formed elements, including cells and cell fragments. Blood plasma, which makes …
Blood plasma contains approximately 92% water and 8% solutes. Proteins comprise about 7% of blood plasma. Of these, higher molecular weight proteins …
Hematopoiesis, or hemopoiesis, is the production of the formed elements in blood from common progenitors, called hematopoietic stem cells, or HSCs. During …
Hemangioblasts, the multipotent stem cells of mesodermal origin, give rise to hematopoietic stem cells or HSCs. The HSCs undergo hematopoiesis to produce …
Hematopoietic growth factors are a group of regulatory and signaling molecules that influence the differentiation of hematopoietic stem cells, or HSCs. …
Red blood cells  (RBCs) transport oxygen to all body tissues. These cells survive only for 120 days and then need to be replenished. Erythropoiesis …
There are 4.2 to 6 million erythrocytes, or red blood cells, per microliter of blood. These small cells are flattened biconcave discs with depressed …
Hemoglobin is a tetrameric globular protein consisting of two alpha and two beta polypeptide chains. Each of these chains has an iron-containing heme …
The circulating erythrocytes frequently squeeze through blood capillaries, damaging their plasma membrane due to constant friction. After about 100 to 120 …
Erythrocyte disorders are broadly categorized into anemic and polycythemic conditions. Anemia develops due to the low oxygen-carrying capacity of the …
A healthy individual has about 4,500 to 11,000 leukocytes or white blood cells per microliter of blood, accounting for about 1% of blood volume. Unlike …
Leukocytes containing cytoplasmic granules are classified as granular, while those with relatively clear cytoplasm are termed agranular. All granulocytes …
Leukocyte disorders are characterized by either leukopenia, an abnormally low leukocyte count, or leukocytosis, a very high leukocyte number. Bone marrow …
A microliter of blood contains 150,000 to 400,000 small, disc-shaped cell fragments called platelets or thrombocytes. These fragments originate in the …
Hemostasis is a series of rapid, defensive reactions triggered to stop excessive bleeding and promote healing after a vascular injury. It is a highly …
Hemostasis begins with a vascular spasm, also known as the vascular phase. It starts immediately after any damage to a blood vessel, causing a sudden …
In an injured blood vessel, the platelet phase – which overlaps with the vascular phase – begins about 15-20 seconds after the onset of vascular spasm. As …
Coagulation or clotting is the last hemostasis phase. It involves a series of chemical reactions to form a blood clot, reinforcing the initial platelet …
The extrinsic and intrinsic pathways of coagulation involve reaction cascades of clotting factors. They merge into the common pathway, eventually forming …
The activated platelets in a blood clot extend projections and interact with other platelets and fibrin fibers. Within 30 to 60 minutes, the contractile …
Thromboembolic disorders and bleeding disorders are two types of disruptions in hemostasis. The thromboembolic disorders are characterized by the …
The ABO blood group system is based on the presence of specific antigens or agglutinogens on the red blood cells, or RBCs, and antibodies or agglutinins …
The Rhesus or Rh antigen is a class of agglutinogen on the red blood cells or RBCs. Its presence or absence categorizes a person as Rh-positive or …
The antigens A, B, and Rh on the surface of red blood cells serve as the foundation for blood grouping. When these antigens come in contact with their …
A blood transfusion is a medical procedure to replace lost whole blood or its components due to injury, surgery, or treatment for conditions like anemia …
Bone marrow transplants replace diseased marrow with healthy marrow from a compatible host. It can cure several cancers and genetic disorders like …
The cardiovascular system regulates erythrocyte numbers for optimal oxygen transport. It also prevents erythrocyte over-proliferation, maintaining blood …
Clonal hematopoiesis is a prevalent age-associated condition that results from the accumulation of somatic mutations in hematopoietic stem and progenitor …
The bone marrow (BM) is the soft tissue found within bones where hematopoiesis, the process by which new blood cells are generated, primarily occurs. As …
Robust point-of-care methods are required to estimate anemia at the population level. The accurate methods are lab-based and cannot be used at the point …