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Blood Basics

Red Blood Cells (Erythrocytes)

• Term: Erythrocytes

• Main Function: Transport oxygen in the bloodstream.

Components of Blood

• Three Components:

  • Formed elements

  • Plasma

  • Buffy coat

Hematocrit

• Definition: Percentage of erythrocytes in total blood volume.

• Composition:

  • Erythrocytes: 45%

  • Leukocytes/Platelets: >1%

  • Plasma: 55%

Key Proteins in Blood

• Albumin:

  • A protein important for osmotic pressure in blood, keeping water in circulation.

• Hemoglobin:

  • An iron-containing protein that transports oxygen within red blood cells.

Anemia

• Definition: Reduced oxygen-carrying capacity of blood.

• Causes:

  • Decrease in the number of RBCs

  • Inadequate hemoglobin in RBCs

  • Abnormal hemoglobin in RBCs

• Sickle Cell Anemia:

  • Disorder where RBCs become sickle-shaped, leading to shortages of healthy RBCs and potential blockages in blood flow.

Blood Disorders

• Polycythemia: Excessive or abnormal increase in erythrocytes.

• Leukocytosis: Elevated WBC count (above 11,000 cells/mm), often due to infection.

• Leukopenia: Low WBC count, may be caused by drugs (e.g., corticosteroids).

• Leukemia: Transformation of Bone marrow cells from healthy to cancerous.

White Blood Cells (Leukocytes)

Function

• Main Function: Defend against diseases, including bacteria, viruses, and parasites.

Types of White Blood Cells

• Granulocytes vs Agranulocytes:

  • Granulocytes: Visible granules in cytoplasm and lobed nuclei.

  • Agranulocytes: No visible granules and have round nuclei.

Specific White Blood Cells:

1. Neutrophils:

   • Stain: Pink

   • Characteristics: Multi-lobed nucleus

   • Function: Phagocytic action at infection sites.

2. Eosinophils:

   • Stain: Red

   • Function: Increase during allergic and parasitic infections.

3. Basophils:

   • Stain: Dark blue

   • Function: Release histamine to promote inflammation.

4. Lymphocytes:

   • Stain: Dark purple

   • Function: Help with the immune response, found in lymphatic tissue.

5. Monocytes:

   • Stain: Gray-blue

   • Function: Transform into macrophages to fight chronic infections.

Blood Cell Formation

• Hemocytoblast: Stem cells giving rise to all blood cells.

• Hematopoiesis: The process of blood cell formation occurring in red bone marrow.

• Megakaryocytes: Large cells that fragment to produce platelets, crucial for blood clotting.

Hemostasis

• Definition: Stopping blood flow after injury.

• Three Phases of Hemostasis:

  1. Platelet Plug Formation: Platelets adhere to damaged vessel walls, forming a temporary plug.

  2. Vascular Spasms: Constriction of blood vessels to minimize blood loss.

  3. Coagulation: Complex process where thrombin converts fibrinogen to fibrin, forming a stable clot.

Related Terms

• Thrombus: Abnormal blood clot forming inside a vessel.

• Embolus: A clot that detaches and travels, potentially causing strokes.

• Thrombocytopenia: Low platelet count, leading to excessive bleeding.

• Hemophilia: A genetic disorder with missing clotting factors, resulting in excessive bleeding.

Blood Types and Transfusions

Antigens

• Definition: Proteins on the surface of RBCs aiding immune recognition.

• ABO Blood Groups: A, B, AB, O

  • Most Common: O

  • Least Common: AB

Transfusion Reactions

• Definition: Occur when incompatible blood types are mixed.

• Cause: Antibodies in plasma react with donor blood antigens, leading to clumping (agglutination).

Rh Factor and Reactions

• First Exposure: An Rh- person lacks Rh antibodies with first exposure to Rh+ blood.

• Second Exposure: Rh- person develops antibodies, leading to a transfusion reaction.

Erythroblastosis Fetalis

• Definition: Condition where Rh- mother carries Rh+ baby, mixing blood develops antibodies in the mother.

• Prevention: Administration of Rhogam to eliminate Rh+ cells before the mother’s blood reacts.