Hematologic System and Blood Clotting

Blood Disorders Overview

• The hematologic or hematopoietic system includes blood, blood vessels, and blood-forming organs (bone marrow, spleen, liver, lymph nodes, and thymus gland)
• Blood's major function is transporting oxygen and nutrients to cells and removing CO2 and metabolic waste.
• Blood also plays a role in hormone transport, inflammation and immune responses, temperature regulation, fluid-electrolyte balance, and acid-base balance.
• Blood has three main functions: transportation (carrying oxygen, nutrients, hormones, and waste throughout the body); regulation (maintaining homeostasis by regulating body temperature, pH, and water levels); and protection (protecting the body from disease and foreign molecules and preventing excessive blood loss).

Hematopoiesis (Blood Cell Formation)

• Hematopoiesis occurs mainly in red bone marrow, specifically in flat bones (skull, ribs, pelvis, sternum) and proximal epiphyses of the humerus and femur.
• Erythropoiesis (RBC production) is a continuous and active process.
• Red blood cells (RBCs) have a lifespan of about 120 days.
• Iron from destroyed RBCs is recycled for new RBC production, facilitated by erythropoietin, a hormone secreted by the kidneys.

Requirements for Erythropoiesis

• Erythropoietin
• Iron
• Folic acid
• Vitamins B6 and B12
• Vitamin C

Main Components of Blood: Plasma

• Plasma is the liquid portion of blood, comprising about 55% of blood volume.
• It's mostly water and also contains proteins, fats, vitamins, minerals, hormones, and glucose.
• Plasma carries red blood cells, white blood cells, and platelets throughout the body.
• Plasma is straw-colored, non-living, and a mixture of protein, enzymes, nutrients, wastes, hormones, and gases.
• It contains 91% water and 9% solids (most inorganic molecules: Na, Ca, Cl, HCO3-, K, Mg).
• Albumin, a plasma protein, is crucial for transporting substances like drugs, hormones, and fatty acids by helping them dissolve in plasma.
• Nutrients include glucose, amino acids, fats, cholesterol, phospholipids, vitamins, and minerals.
• Gases are oxygen (O2) and carbon dioxide (CO2).
• Electrolytes include sodium.
• Other components include amino acids, nitrogenous waste (urea, uric acid, creatinine).

Main Components of Blood: Red Blood Cells (Erythrocytes)

• RBCs carry oxygen from lungs to the body's cells.
• They are created in bone marrow.
• They are responsible for blood's red color..
• Normal RBC count: 4-6 million/mm³
• Hematocrit (HCT) measures the percentage of RBCs in a given volume of blood, indicating oxygen-carrying capacity.
• Normal HCT values: Female (37-48%), Male (45-52%)
• Normal hemoglobin (Hb) values: Female (12-16 g/100ml), Male (13-18 g/100ml)
• RBC destruction occurs in liver and spleen.
• Bilirubin and iron are byproducts of hemoglobin breakdown and are recycled.
• Iron is transported to the bone marrow for new RBC production via transferrin.

Main Components of Blood: White Blood Cells (Leukocytes)

• Leukocytes (white blood cells) fight infections and diseases.
• Average leukocyte count: 4,000-11,000/mm³.
• Leukocytes protect the body against damage.
• Leukocytes can slip in and out of blood vessels (diapedesis)..
• Leukocytosis: total WBC count above 11,000/mm³ (indicates infection).
• Leukopenia: abnormally low WBC count.
• Types: Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

White Blood Cell Types (detailed)

• 1. Lymphocytes (B cells and T cells): B cells produce antibodies to neutralize antigens, while T cells directly attack antigens.
• 2. Macrophages: engulf foreign particles; arise from monocytes

Main Components of Blood: Platelets (Thrombocytes)

• Platelets are small, colorless cell fragments that help stop bleeding by sticking to blood vessel walls.
• They live for about 5-10 days.
• Produced in bone marrow.
• Normal platelet count: 250,000-450,000/mm³.
• Crucial for blood clotting (coagulation)

Hemostasis (Blood clotting)

• Three major phases: platelet plug formation, vascular spasms, and coagulation/blood clotting.
• Platelets adhere to injured vessel lining, releasing chemicals to attract more platelets.
• Platelets release serotonin, causing vessel spasms, reducing blood flow.
• Damaged cells release thromboplastin activates clotting cascade, resulting in blood clot formation.
• Serum is squeezed from the clot, pulling the ruptured edges of the vessel together.

Plasma Clotting Factors

• Various proteins crucial for blood clotting, including fibrinogen, prothrombin, tissue thromboplastin, calcium, proacelerin, proconvertin, and more.

Anemia

• Anemia is a condition where RBCs or hemoglobin levels are below normal.
• It leads to hypoxia and ischemia.

Classifications of Anemia

• Anemia can be classified based on etiology (causing factors):
• Bleeding (accidents, trauma, surgery, childbirth, etc.)
• Hypoproliferative (low RBC production due to iron, B12, folic acid deficiencies, chronic disease, cancer, etc.)
• Hemolytic (increased RBC destruction due to spleen enlargement, sickle cell disease, thalassemia, etc.)
• Anemia can also be categorized by morphology (RBC size and hemoglobin content: microcytic, normocytic, macrocytic, normochromic, hypochromic, hyperchromic)

Etiology: Classification of Anemia (continued)

• Systemic Infections
• Bone Marrow Aplasia :
  • Aplastic anemia
  • Pure red cell aplasia
• Iron Deficiency
• Folate and vitamin B12 deficiency
• Protein deficiency

Types of Anemia

• Iron-deficiency anemia
  • Most common type
  • Caused by depleted iron stores
  • Associated with bleeding, increased metabolic demands, and dietary inadequacies

Pathophysiology of different conditions:

• Descriptions of pathophysiology for iron deficiency anemia, hemolytic anemia, sickle cell anemia, thalassemia, megaloblastic anemia, aplastic anemia are included based on given data, but not fully exhaustive in all possible instances

Signs and symptoms

Varying depending on the specific blood disorder. Include fatigue, pallor, pale oral mucosa, brittle nails, splitting of nail beds (koilonychia), palmar creases, angular cheilitis, pale oral mucosa, oral candidiasis, recurrent aphthous stomatitis, erythematous mucositis, burning mouth, shortness of breath, rapid heartbeat and dizziness. Also includes specific symptom profiles of other individual conditions as listed in earlier notes.

Laboratory Findings

• Includes specific values or abnormalities associated with a particular condition. Varies considerably from condition to condition as described earlier

Treatments for each condition

Methods for treating anemia range from oral iron supplements to blood transfusions, and treatments for specific conditions like sickle cell anemia are mentioned. Additional treatments are also addressed, for instance, chemo, radiation and blood transfusions for different blood disorders

Platelet Disorders

• Disorders like thrombocythemia (excess platelets), ITP (immune thrombocytopenic purpura), hemophilia, Von Willebrand disease, and disseminated intravascular coagulation (DIC) are described.

Blood Smear

• A method for identifying different types of blood cells.

Additional Key Concepts

• Normal lifespan of RBCs.
• Locations of blood cell formation and destruction
• Important elements in blood clotting and associated factors

Explore the blood clotting process, the components of the hematologic system, and the role of platelets. Understand blood's function in transporting oxygen, nutrients, and waste products, and its role in maintaining homeostasis. Learn about iron deficiency anemia and the importance of Vitamin K.