Blood pt.2 and Heart pt.1

White Blood Cells (WBCs)

  • Types of WBCs:

    • There are five primary types of white blood cells:

    1. Neutrophils (60-65%)

      • Primarily attack and respond to bacteria.

    2. Basophils

      • Release histamine and heparin in inflammatory responses.

    3. Eosinophils

      • Involved in combating parasites and allergic reactions.

    4. Monocytes

      • Differentiate into macrophages (e.g., lung macrophages, liver macrophages) when they exit circulation, playing a key part in phagocytosis.

    5. Lymphocytes (30-40%)

      • Further classified into:

      • T cells (including cytotoxic, memory, and regulatory T cells)

      • B cells (which differentiate into plasma cells).

  • Function of Monocytes and Macrophages:

    • Macrophages perform essential protective roles by engulfing pathogens through a process called phagocytosis.

Blood Cell Production and Lifespan

  • Production Rate:

    • Approximately 5,000 to 10,000 WBCs are produced daily.

  • Lifespan of Red Blood Cells (RBCs):

    • RBCs have a lifespan of about 120 days.

  • Low Blood Cell Counts:

    • Anemia: Low RBC count.

    • Leukemia: A condition signifying cancer, specifically an overproduction of WBCs.

Stem Cells and Blood Cell Types

  • Stem Cell Types:

    • Myeloid Stem Cells: Produce six different blood cell types.

    • Lymphoid Stem Cells: Produce lymphocytes.

  • Differentiation Factors:

    • Various chemical factors influence the differentiation of stem cells into specific blood cell types.

Platelets and Hemostasis

  • Lifespan of Platelets:

    • Platelets survive for about 9 to 12 days.

  • Normal Platelet Count:

    • Ranges from 150,000 to 500,000 per microliter.

  • Diseases Related to Platelet Count:

    • Thrombocytopenia: Abnormally low platelet count.

    • Thrombocytosis: Abnormally high platelet count.

  • Functions of Platelets:

    1. Release clotting chemicals necessary for blood clotting.

    2. Temporarily patch damage to blood vessel walls.

    3. Participate in clot retraction after clot formation.

  • Coagulation Time:

    • Typically takes 3 to 6 minutes for blood to clot.

  • Thrombopoiesis:

    • The process of platelet synthesis occurs mainly in the bone marrow.

Blood Clotting Mechanism (Hemostasis)

Phases:

  1. Vascular Phase:

    • Endothelial Cells: Release chemicals in response to injury, promoting vasoconstriction and increasing blood vessel stickiness.

    • Chemicals released include ADP and prostacyclin.

  2. Platelet Phase:

    • Platelets aggregate at the site of injury, forming a platelet plug within 15 seconds after injury.

    • Release additional factors facilitating aggregation.

  3. Coagulation Phase:

    • Involves a chain reaction of enzymes, converting plasma proteins from inactive to active forms (e.g., fibrinogen to fibrin).

    • Pathways Involved:

      • Extrinsic Pathway: Triggered by external trauma; involves tissue factor and factor VII.

      • Intrinsic Pathway: Triggered by blood vessel trauma; involves factors XII, VIII, and X.

      • Common Pathway: Both pathways lead to factor X activation, producing prothrombinase.

  • Key Enzymes and Proteins:

    • Prothrombin: Activated to form thrombin, converting fibrinogen into fibrin (the mesh forming clots).

    • Importance of Calcium Ions and Vitamin K: Essential for various stages of the clotting cascade.

Recovery from Clotting

  • Clot Retraction: Occurs about one hour post-injury, where platelets contract to stabilize the clot.

  • Anticoagulants: Such as heparin, help modulate clotting processes to maintain homeostasis.

Heart Anatomy and Circulation

  • Pulmonary Circulation: Carries blood to and from the lungs.

  • Systemic Circulation: Delivers blood to and from the rest of the body.

  • Heart Chambers:

    • Right Atrium: Receives blood via the superior and inferior vena cava.

    • Right Ventricle: Pumps blood to pulmonary arteries.

    • Left Atrium: Receives oxygenated blood from pulmonary veins.

    • Left Ventricle: Pumps oxygenated blood to the body.

  • Great Vessels Associated with the Heart:

    • Pulmonary Trunk: Splits into left and right pulmonary arteries.

    • Coronary Arteries: Supply blood to the heart muscle itself.

Coronary Artery Disease

  • Atherosclerosis: Characterized by fat deposits narrowing arteries, potentially leading to heart attacks.

  • Diagnostic Procedures: Include angiograms to detect blockages, followed by angioplasty or bypass surgery based on severity.

Cholesterol and Lipid Management

  • Blood Profile Composition Include:

    • Total cholesterol, LDL, HDL, and triglycerides.

  • Ideal Levels: Maintain HDL above 40 mg/dL and total cholesterol below 200 mg/dL to reduce heart attack risk.

Plasma Proteins:

  • Albumin 60%:

    • Maintains osmotic pressure and transports fatty acids, thyroid and steroid hormones in the blood.

    • synthesized: liver

  • Globulins 35%:

    • Functions in immune response (antibodies) and transport (lipids, hormones).

    • synthesized: liver and immune system

  • Fibrinogen 4%:

    • Crucial for blood clotting; converted into fibrin during the clotting process.

    • synthesized: liver