Physiology Chapter: Blood

Physiology (0603302)

• Course: Physiology
• Chapter: Blood
• Semester: Summer 2023/2024
• Instructor: Dr. Mohammad A. Abedal-Majed
• Institution: The University of Jordan, School of Agriculture

Blood

• Liquid connective tissue that circulates through blood vessels, pumped by the heart
• Functions:
  • Transportation: Transports nutrients (amino acids, lipids, glucose), hormones, and oxygen to cells; transports wastes and carbon dioxide away from cells
  • Regulation: Buffers pH (7.35-7.45), regulates body temperature (vasodilation/vasoconstriction)
  • Protection: Prevents blood loss through clot formation; protects against foreign substances (antibodies and white blood cells)

Characteristics of Blood

• Blood volume: Males (5-6 liters), Females (4-5 liters) (dependent on individual size and gender)
• Color: Red; arterial blood is brighter red (high oxygen level); venous blood is darker red (less oxygen)
• pH: Venous blood typically has a lower pH than arterial blood (7.35-7.45 arterial, 7.32-7.42 venous)

Blood Composition

• Cellular portion (formed elements): Lower portion of a centrifuged blood sample, including buffy coat (white blood cells and platelets) and red blood cells (RBCs)
• Fluid portion (plasma): Upper portion of a centrifuged blood sample (55% of blood volume); primarily water and contains proteins, electrolytes, nutrients, waste products, and gases
  • Plasma composition: Proteins (albumins, globulins, fibrinogen), other solutes, gases, formed elements (RBCs, WBCs, platelets); various concentrations and levels

Components of Blood

• A-plasma (fluid portion):
  • Water (91-92%): Transport medium
  • Proteins (6-8%): Maintain blood volume and pressure (Albumin, globulins, fibrinogen)
    • Albumin (60%): Transport protein and steroid hormones
    • Globulins (35%): Transport hydrophobic lipids, vitamins, ions, and hormones, including antibodies
    • Fibrinogen (4%): Coagulation protein
    • Regulatory proteins (<1%): Enzymes, proenzymes, and hormones
• Other solutes (1-2%): Electrolytes (Na+, Cl-, HCO3-, K+, Ca+2), organic nutrients, and organic wastes (urea, creatinine)
• Dissolved gases (O2 and CO2)

Cellular Component of Blood

• Erythrocytes (RBCs): Biconcave discs, lack a nucleus and mitochondria; transport oxygen and CO2; lifespan 70-150 days (4.6-6.2 million/mm³ in males and 4.5-5.1 million/mm³ in females).
• Leukocytes (WBCs): Immune response, various types with different functions (eosinophils, basophils, neutrophils, monocytes, lymphocytes); crucial role in defending against infection and pathogens
• Thrombocytes (Platelets): Cellular fragments, essential for hemostasis and blood clotting; critical role in wound healing and preventing blood loss; average lifespan 7-14 days; (150,000-350,000 /mm3)

Synthesis of Erythrocytes

• Areas of erythropoiesis
  • Embryonic life (yolk sac)
  • Middle trimester of gestation (liver, spleen, lymph nodes)
  • Last month of gestation and after birth (bone marrow)
  • Up to five years (bone marrow of all bones)
  • Age twenty and up (bone marrow only)
• Factors stimulating erythropoiesis: Low oxygen levels (hypoxia), high altitudes, lung diseases, heart failure; erythropoietin is a crucial hormone

Hematocrit

• Definition: Percentage of blood volume occupied by red blood cells
• Normal range: Males (42%-52%), Females (37%-47%)

Anemia

• Condition where blood's oxygen-carrying capacity is reduced below normal
• Types:
  • Nutritional anemia: Diet deficiency (iron deficiency)
  • Pernicious anemia: Inability to absorb B12
  • Aplastic anemia: Bone marrow failure to produce blood cells

Polycythemia

• Condition with excess circulating red blood cells
• Types: Primary and secondary; high altitudes, genetic factors, or other underlying medical conditions can cause it

White Blood Cells (Leukocytes)

• Mobile units of the immune system
• Destroy and remove old or aberrant cells, attacking infectious agents
• Functions: Phagocytosis and antibody production
• Colorless due to lack of hemoglobin
• Contain nuclei and mitochondria, allowing amoeboid movement to infection sites
• Lifespan varies from 13 to 20 days
• Types of WBCs: Granulocytes (neutrophils, eosinophils, basophils), and Agranulocytes (monocytes and lymphocytes).

Thrombocytes (Platelets)

• Cellular fragments with no nucleus, crucial for hemostasis
• Irregularly shaped
• Cessation of bleeding, maintains vascular integrity
• Life span of 7 to 14 days (150,000-350,000 /mm3).

Blood Clotting (Coagulation)

• Cascade of reactions activating coagulation factors, leading to the conversion of fibrinogen to fibrin, forming a stable clot
• Essential for hemostasis
• Factors such as vitamin K are necessry for the process

Hemostasis

• Cessation of bleeding
• Three mechanisms involved:
  • Vasoconstriction
  • Platelet aggregation
  • Clot formation

Plasma vs Serum

• Plasma: Blood fluid that contains clotting factors
• Serum: Plasma with clotting factors removed

Clinical Applications

• Hemostasis and blood flow for normal functions; dysfunctions (ischemia); clinical signs of oxygenation/perfusion insufficiency (e.g., mucous membrane color, capillary refill time)
• Blood tests and assessment of the circulatory system.

Explore the functions and characteristics of blood in this quiz based on the Physiology course. Learn about its roles in transportation, regulation, and protection. This quiz will challenge your understanding of blood volume, color, and pH levels.