Hematological System Overview

Hematological System Overview

• Blood is composed of 55% plasma and 45% formed elements (red cells, white cells, and platelets).
• Total blood volume is 8% of body weight.
• Blood is drawn and separated into components through centrifugation.
• Plasma is the clear yellow liquid portion of blood, primarily water (91.5%).
• Plasma proteins include albumin, globulins, fibrinogen, and other proteins.
• Plasma proteins primarily function as clotting agents and antibodies.
• Water in plasma acts as a transport medium.
• Electrolytes in plasma maintain osmotic balance, buffer pH changes, and support nerve and muscle function.
• Plasma also transports nutrients, wastes, gases, and hormones.

Blood Components

• Plasma (55%) is primarily water (90%), plasma proteins (7%), and other substances (including electrolytes, nutrients, and hormones).
• Blood cells (45%) include red blood cells (RBCs, 99%), and white blood cells (WBCs) and platelets (<1%).

Functions of Plasma

• Transportation of dissolved gases, nutrients, and hormones to tissues and cells.
• Oxygen transport from the lungs and carbon dioxide removal.
• Nutrient delivery from the digestive tract.
• Hormone delivery to target organs.
• Waste product transport to the kidneys, lungs, and other organs.

Functions of Blood

• Prevents excessive fluid loss from damaged blood vessels through platelets and clotting proteins (hemostasis).
• Protecting against pathogens and toxins through white blood cells.
• Regulates body pH and electrolyte composition through buffers.
• Blood regulates body temperature through the dilation or contraction of blood vessels.

Blood Cells

• Blood cells are produced from hematopoietic stem cells.
• Three main types: red cells (erythrocytes), white cells (leukocytes), and platelets (thrombocytes).

Red Blood Cells (Erythrocytes)

• Disc-shaped with a large surface area.
• Can change shape.
• Lack nuclei and organelles.
• Contain hemoglobin for oxygen transport from lungs to body cells and carbon dioxide removal.
• Short lifespan (~120 days).
• Ruptured RBCs are destroyed in spleen, and phagocytic WBCs clear the debris.
• RBC production described through a diagram

Mechanism of Hemoglobin Transport

• Hemoglobin consists of four heme molecules, each binding to one oxygen molecule.

White Blood Cells (Leukocytes)

• Body's defense system.
• Destroy invading microorganisms and abnormal cells (e.g., cancer).
• Clean up cellular debris (phagocytosis).
• Types and their functions: neutrophils, eosinophils, basophils, monocytes, and lymphocytes (B and T lymphocytes).

Platelets (Thrombocytes)

• Cell fragments from megakaryocytes.
• Release important chemical mediators for blood clotting.
• Involved in the hemostasis process which has three stages: Vascular spasm, platelet plug formation and blood coagulation (clotting).

Hemostasis

• Three-step process of stopping bleeding: vascular spasm, platelet plug formation, and blood coagulation.
• Clotting cascade transforms blood from liquid to solid with multiple steps involving fibrinogen to fibrin.

Clot Dissolution

• Plasmin enzyme dissolves blood clots.
• Plasminogen is the inactive precursor activated by factor XII (Hageman Factor), occurring simultaneously with clot formation.

Clotting Disorders

• Thrombus (excessive clot formation) and embolus (free-floating clot).
• Hemophilia, lack of clotting factors, leading to hemorrhage.

Types of Anemia and Polycythemia

• Anemia (low hemoglobin): Nutritional, pernicious, aplastic, renal, hemorrhagic, hemolytic.
• Polycythemia (abnormally high hematocrit): Primary and secondary.

Additional Information

• Questions about blood composition, red blood cell function, hemoglobin function, and roles of neutrophils and lymphocytes were included in the presentation.