Hemostasis and Coagulation Quiz

Pathophysiology of Hematologic System

• Components of the Hematologic System include all blood elements (plasma, blood cells) and lymphoid organs (e.g., spleen, bone marrow).
• Plasma minus clotting factors equals serum.

Blood Components

• Plasma constitutes 55% of total blood volume.
• Plasma is mostly water (91%).
• Soluble blood proteins make up 7% of plasma.
• Hormones, nutrients, and electrolytes account for the remaining 2%.
• Blood elements (red blood cells, white blood cells, blood platelets) make up 45% of total blood volume.

Plasma

• Plasma is the liquid portion of blood.
• It's pale yellow and composed of 91% water and 9% other substances.
• It contains suspended substances that don't settle out (colloid).
• Key plasma proteins include albumin (regulates water movement), globulin (immune system/transport), and fibrinogen (blood cell formation).

Blood Cells

• Blood cells include erythrocytes (RBCs), leukocytes (WBCs), and thrombocytes (platelets).
• Leukocytes (WBCs) are further categorized into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
• Lymphocytes are subdivided into T lymphocytes and B lymphocytes.

Functions of the Hematologic System

• Transport Medium: RBCs and plasma transport gases, nutrients, vitamins, hormones, and waste products.
• Defensive Function: White blood cells, through phagocytosis, defend against invading microorganisms; antibodies and sensitized T lymphocytes also help.
• Hemostatic Function: Platelets and coagulation factors stop blood extravasation (bleeding) due to vessel injury.
• Homeostatic Function: The whole blood maintains a constant internal environment composition.

Fate of Erythrocytes (RBCs)

• RBCs cannot divide, grow, or synthesize proteins.
• Their lifespan is 100-120 days.
• They're removed by phagocytosis in the spleen or liver.
• New RBCs are produced in the bone marrow.
• RBC production increases when oxygen levels decrease or during pregnancy.

Hemoglobin

• Hemoglobin is the protein in red blood cells that transports oxygen from lungs to tissues and carbon dioxide from tissues to lungs.
• Hemoglobin consists of four globulin chains.

Types of Hemoglobin

• HbA1: The major hemoglobin in humans, appearing 12 weeks after birth (minor component of normal adult hemoglobin).
• HbF: Synthesized during fetal development and in newborn infants, replaced by HbA in the first few months of life
• HbA1c: Has glucose residues attached to beta-globin chains and increased levels indicate poor blood sugar control. HbA1c can be used as a monitoring tool for diabetes control.

HBS (Sickle Cell Anemia)

• HBS contains two mutant beta-globin chains.
• Glutamate at position 6 is replaced by valine in mutant chains.
• RBCs in HBS have a shorter lifespan (less than 20 days compared to 120 days for normal RBCs).
• Anemia is a consequence of HBS.

Normal Values Related to RBCs

• Red blood cell count: 4.0 to 5.5 million/mL of blood for both genders.
• Hemoglobin: 14.0-17.5 gm/100mL for males; 12.0-16.0 gm/100mL for females.
• Hematocrit (percentage of red blood cells): 42-52% for males; 36-48% for females.

Normal Values Related to WBCs

• Total leukocyte count: 4,000-11,000/mm3.
• Classification (differential leukocyte count): Granulocytes (neutrophils, eosinophils, basophils); Agranulocytes (lymphocytes, monocytes).
• Specific percentages for each type of leukocyte are provided.

Normal Values Related to Hemostatic Function (Platelets and Coagulation Factors)

• Platelet count: 150,000-400,000/mm3 (average 300,000/mm3).
• Bleeding time: normally 1-6 minutes.
• Coagulation Tests:
  • Whole blood coagulation time: 6-10 minutes
  • Activated partial thromboplastin time: 30-40 seconds
  • Prothrombin time: 10-14 seconds

Anemia

• Decreased red blood cell count or hemoglobin percentage, or both, leading to decreased oxygen transport to tissues.
• Common symptoms include pale or yellowish skin, fatigue, cold hands and feet, headache, and shortness of breath.

Types of Anemia

• Classified based on red blood cell morphology:
  • Microcytic: small size and lower hemoglobin content.
  • Macrocytic: larger size.
  • Hypochromic: reduced hemoglobin content.

Normocytic Normochromic Anemia

• Results from decreased production or excessive loss of RBCs.
• Causes include bone marrow depression (aplastic anemia) from radiation, chemicals, chemotherapy, infections, or massive hemorrhage, or hemolysis of RBCs.

Hemolytic Anemia

• Red blood cells are destroyed faster than bone marrow can replace them.
• Acquired causes include chemical/bacterial toxins, drugs, snake venom, autoimmune disorders (incompatible blood transfusions), cancers, and certain viral/parasitic infections (malaria).
• Hereditary causes include hereditary spherocytosis, sickle cell anemia, and thalassemia.

Manifestations of Hemolytic Anemias

• Common anemia symptoms.
• Jaundice (yellowing of skin and mucous membranes) due to increased blood bilirubin.
• Sickling of RBCs in sickle cell anemia results in increased blood viscosity and reduced blood flow to tissues leading to hypoxia and pain.
• Splenomegally (enlarged spleen).

Microcytic Hypochromic Anemia

• Smaller RBCs with lower hemoglobin.
• Causes include iron deficiency (low iron intake, poor absorption, or chronic blood loss)

Macrocytic Anemia

• Larger RBCs.
• Causes include vitamin B12 or folic acid deficiency.

Pathophysiological Effects of Anemia

• Decreased blood viscosity
• Increased blood flow rate
• Increased venous return
• Increased cardiac output to compensate for decreased oxygen content in blood
• Excessive production of bile pigments in hemolytic anemia causes jaundice
• In pernicious anemia (lack of vitamin B12), sensory disturbances due to spinal cord degeneration.

Polycythemia

• High RBC count.
• Relative Polycythemia: Decreased plasma volume; increased RBC concentration.
• Primary Polycythemia: Bone marrow makes too many RBCs, also producing too many white blood cells and platelets; thickening the blood and causing complications like blood clots or bleeding.
• Secondary Polycythemia: Caused by chronic hypoxia (e.g., high altitude).

Manifestations of Polycythemia

• Increased blood volume
• Increased blood viscosity
• Risk of thrombosis
• Occlusion of small blood vessels
• Impaired blood flow to tissues (ischemia)
• Hepatosplenomegally.

Pathophysiology of Hemostasis

• Definition: Stoppage of bleeding when a blood vessel is injured.
• Steps:
  • Vasoconstriction of blood vessels.
  • Formation of a platelet plug.
  • Formation of a blood clot.
  • Growth of fibrous tissue.

Abnormalities in Coagulation Process

• Causes of increased bleeding tendencies: genetic (like hemophilia), acquired (vitamin K deficiency, liver diseases), or drug-induced.
• Characteristics: prolonged clotting time.

Hemophilia

• Rare bleeding disorder due to clotting factor deficiency.
• Manifestations: mild to severe bleeding problems, excessive bleeding with trauma or surgery, and internal bleeding within soft tissues (muscles, joints).
• Treatment: injury prevention and factor replacement therapy.

Vitamin K Deficiency

• Vitamin K is necessary for clotting factors (II, VII, IX, and X) synthesis.
• Sources are exogenous (dietary) and endogenous (intestinal bacteria).
• Causes of deficiency include malabsorption, antibiotic-induced bacterial flora destruction, and certain medications.
• Treatment includes vitamin K administration and deficient factor supplementation.

Liver Diseases

• Liver produces clotting factors.
• Liver disease reduces clotting factor production causing coagulation defects resulting in increased bleeding tendencies.
• Examples: hepatitis, cirrhosis, liver cancer, liver failure

Drug-Induced Abnormalities (increased bleeding)

• Anticoagulants like Warfarin and heparin inhibit blood clotting

Abnormalities in Blood Platelets

• Decreased platelet count or impaired platelet function leads to increased bleeding tendencies.
• Characteristics: prolonged bleeding time.

Increased Blood Coagulability

• Causes may include underlying inherited disorders of coagulation, obesity, cancer, sepsis, polycythemia, prolonged bed rest, venous stasis, and trauma/surgery.
• Danger: increased risk of thrombosis.

Test your knowledge on hemostasis and coagulation processes. This quiz covers various conditions related to vitamin K deficiency, liver disease, and hemophilia treatment. Understand the factors that affect blood coagulation and platelet function.