PHYL 205 Blood and Circulatory System

Introduction to Blood

• The circulatory system comprises the heart, blood vessels, and blood.
• Hematology is the branch of medicine focused on the study of blood.
• Primary functions of the circulatory system include:
  • Transport: Delivers oxygen (O2), carbon dioxide (CO2), nutrients, waste products, hormones, and stem cells throughout the body.
  • Protection: Involves immune responses including inflammation, limiting infection spread, destroying pathogens and cancer cells, neutralizing toxins, and initiating clotting mechanisms.
  • Regulation: Maintains fluid balance, stabilizes blood pH, and assists in temperature control.

Components and General Properties of Blood

• An adult typically contains 4-6 liters of blood.
• Blood is classified as a liquid connective tissue.
  • Plasma: The matrix of blood, characterized as a clear, light yellow fluid.
  • Formed elements: Comprised of blood cells and cell fragments, includes red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Formed Elements of Blood

• Types of blood cells:
  • Erythrocytes: Carry oxygen via hemoglobin.
  • Leukocytes: Divided into several types including:
    • Neutrophils: Most abundant white blood cells, crucial in fighting infections.
    • Lymphocytes: Key players in immune response (includes small lymphocytes and large lymphocytes).
    • Monocytes: Largest type of white blood cell, essential in pathogen defense and tissue repair.
    • Eosinophils: Combat multicellular parasites and allergic responses.
    • Basophils: Involved in inflammatory reactions, releasing histamine.

Separating Plasma From Formed Elements of Blood

• Blood can be separated into its components through centrifugation.
  • Plasma: Comprises 55% of whole blood and contains water, electrolytes, nutrients, hormones, and waste products.
  • Buffy coat: A thin layer that contains leukocytes and platelets, situated between plasma and red blood cells.