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Platelet Plug Formation

  • Adhesion

    • Proteins on the surface bind to collagen fibers and endothelial cells of blood vessels.
    • Collagen is only exposed if the blood vessel is damaged.

  • Activation

    • After adhesion, platelets become activated, resulting in:
      • Alpha and dense granules fuse with the membrane of the platelet.
      • Exocytosis occurs, releasing contents that cause other platelets to stick to existing ones.
      • Vasodilation of normal vessels.
      • Unrestricted flow in damaged ones.

  • Markers?

    • Importance of identifying inactive and activated platelets in the process.

  • ABO Blood Groups

    • Have antigens on their thin surface known as agglutinogens.

Aggregation

  • Activated platelets stick together, leading to:
    • Formation of a platelet plug as more platelets aggregate.
    • Fibrin fibers lay over the platelet plug, allowing red blood cells (RBCs) to stick and strengthening the plug.
    • Fibrin also connects to damaged vessel walls.

Clotting Disorders

  • Hypercoagulability Disorders

    • Conditions where thrombi remain where they should not be.
    • Symptoms include:
      • Edema, redness/tenderness, shortness of breath, pain in the arm or legs if in the mass.
    • Diagnosis is similar to bleeding disorders.

  • Sickle Cell Anemia

    • Beta-globin peptide is mutated, leading to sickle-shaped RBCs that can clump and block blood vessels.
    • Treatments may include medications to breakdown clots (e.g., alteplase, platelet inhibitors).
    • Symptoms include anemia, pain crises lasting hours to days, pain in joints, chronic pain, and risk of infections.
    • Can be genetic and show symptoms at a young age.

  • General Anemia

    • Lack of enough normal RBCs due to production issues in the bone marrow or due to hemorrhage.
    • Diagnosis involves examining RBCs, looking for excessive destruction in the spleen, complete blood count (CBC) analysis, and history examination.
    • Treatments could involve supplements of iron, vitamin B12, folic acid, or blood transfusions.
    • Symptoms typically include fatigue and dizziness which may lead to strokes.

Bleeding Disorders

  • Caused by defects in platelets, fibrin formation, or vitamin deficiencies.
  • Symptoms involve:
    • Easy bruising, prolonged menstrual cycles, bleeding joints, nosebleeds.
  • Diagnosis includes CBC tests to see how long it takes for blood to clot.
  • Treatment may encompass supplements, transfusions, and clotting factors, with close monitoring.

Blood Cancers

  • Several different types can result from issues such as excessive blood cell production.
  • Symptoms may include swelling of lymph nodes, fatigue, weight loss, and recurrent infections.
  • Diagnosis involves CBC, and potential biopsies for clear categorization.
  • Treatments may include radiation, chemotherapy, immune therapies, or bone marrow transplant.

Hematopoiesis

  • Formation of Blood Elements
    • Begins in the yolk sac of embryos, later transitioning to the liver, spleen, and thymus.
    • In adults, hematopoiesis occurs in the red bone marrow located in the vertebrae, pelvis, sternum, ribs, and ends of long bones (e.g., femur, tibia).
  • Physical Characteristics
    • pH maintained within 7.35-7.45.
    • Blood carries more oxygen and has a density of approximately 1.055 g/mL.
    • Hormones such as aldosterone and antidiuretic hormone regulate blood composition.

Functions of Blood

  • Transportation
    • Carries oxygen from lungs to cells, carbondioxide from cells to lungs, nutrients from the gastrointestinal (GI) tract to cells, waste products to kidneys, and hormones throughout the body.
  • Hemoglobin:
    • Composed of globin proteins with heme groups that carry oxygen and carbon dioxide effectively.
  • Regulating Homeostasis
    • Maintains body temperature and pH levels.
  • Protection
    • Clotting mechanisms to prevent bleeding.
    • White blood cells (WBCs) attack pathogens and disrupt infections.

Immune System Overview

Innate Immunity

  • General Overview
    • Provides immediate defense mechanisms such as barriers, phagocytes, and inflammation responses to pathogens.

Adaptive Immunity

  • Specific Immune Responses
    • Characterized by the ability to recognize specific antigens and build a memory against them.

Lymphatic System

  • Components:
    • Made up of lymphatic vessels, lymph nodes, and lymphatic tissues housing lymphocytes.
    • Major functions include the drainage of excess interstitial fluid, transporting dietary lipids, and facilitating immune responses.
  • Lymphatic Vessels:
    • Similar to veins but contain thinner walls and valves.
    • Covered by layers of smooth muscle for physical movement.
  • Primary Lymphatic Organs:
    • Red bone marrow and thymus (sites where immune cells mature).
  • Secondary Lymphatic Organs:
    • Structures like lymph nodes and spleen where immune responses occur.
    • Filters pathogens from lymph fluid.

Autoimmune Disorders

  • Ankylosing Spondylitis
    • Affects the spine and large joints, symptoms include stiffness and pain.
  • Rheumatoid Arthritis
    • Chronic inflammation of joints caused by immune responses targeting synovial tissue. Symptoms include joint tenderness, swelling, and inflamed eyes.
  • Systemic Lupus Erythematosus (SLE)
    • Affects multiple systems, presenting symptoms of fatigue, fever, and skin rashes.
  • Multiple Sclerosis
    • Autoimmune demyelination of nerves causing motor issues.
  • Severe Combined Immunodeficiency Syndrome (SCIDS)
    • Genetic disorder leading to a lack of effective immune response, causing severe susceptibility to infections.
  • Sjogren’s Syndrome
    • Autoimmune destruction of exocrine glands leading to dry mouth and eyes.

HIV/AIDS

  • Overview
    • Human Immunodeficiency Virus (HIV) attacks helper T-cells, leading to Acquired Immunodeficiency Syndrome (AIDS) if untreated. Symptoms include fever, body aches, and swollen lymph nodes, leading to recurrent infections.
    • Treatments include antiviral medications to slow progression of the virus.