Human Blood Composition and Functions
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Questions and Answers

What is the primary site of erythropoiesis in adults?

  • Spleen
  • Liver
  • Red bone marrow (correct)
  • Yolk sac

    • Which vitamin is NOT essential for erythropoiesis?

  • Vitamin B12
  • Vitamin C (correct)
  • Folic Acid (B9)
  • Iron

    • What is a common feature of iron deficiency anaemia?

  • Elevated folic acid levels
  • Decreased hemoglobin concentration (correct)
  • High levels of Vitamin B12
  • Increased red blood cell production

    • Which factor is essential for the absorption of Vitamin B12?

    <p>Intrinsic factor</p> Signup and view all the answers

    Megaloblastic anaemia is primarily caused by a deficiency in which vitamin?

    <p>Vitamin B12</p> Signup and view all the answers

    What is the average blood volume in an adult?

    <p>5 Liters</p> Signup and view all the answers

    Which of the following is a characteristic of sickle cell anaemia?

    <p>Abnormal shape of red blood cells</p> Signup and view all the answers

    What component makes up approximately 55% of blood?

    <p>Plasma</p> Signup and view all the answers

    What is a common characteristic of iron deficiency anemia?

    <p>Decrease in mean cell volume (MCV)</p> Signup and view all the answers

    Which of the following is a cause of megaloblastic anemia?

    <p>Folate deficiency</p> Signup and view all the answers

    Which type of cells are commonly seen in sickle cell anemia?

    <p>Sickle-shaped red blood cells</p> Signup and view all the answers

    What might result from a deficiency of intrinsic factor related to vitamin B12?

    <p>Pernicious anemia</p> Signup and view all the answers

    What is the primary result of increased red blood cell destruction in anemia?

    <p>Lowered hemoglobin concentration</p> Signup and view all the answers

    What is NOT a characteristic of macrocytic anemia?

    <p>Hyperchromic red blood cells</p> Signup and view all the answers

    Which of the following conditions is primarily hereditary?

    <p>Sickle cell anemia</p> Signup and view all the answers

    In which situation could iron deficiency anemia commonly occur?

    <p>Pregnancy or bleeding</p> Signup and view all the answers

    What is the primary hormone involved in the regulation of erythropoiesis in response to hypoxia?

    <p>Erythropoietin (EPO)</p> Signup and view all the answers

    Which type of anaemia is characterized by a deficiency of iron in the body?

    <p>Iron deficiency anaemia</p> Signup and view all the answers

    Which condition is a result of the abnormal production of hemoglobin leading to the deformation of red blood cells?

    <p>Sickle cell anaemia</p> Signup and view all the answers

    What process produces all blood cells, including red blood cells?

    <p>Haemopoiesis</p> Signup and view all the answers

    Which type of anaemia is often associated with a deficiency of vitamin B12?

    <p>Megaloblastic anaemia including pernicious anaemia</p> Signup and view all the answers

    What is thalassaemia primarily caused by?

    <p>Hereditary defects in hemoglobin production</p> Signup and view all the answers

    In terms of blood composition, what is primarily affected in sickle cell anaemia?

    <p>Red blood cell shape and function</p> Signup and view all the answers

    Which of the following is a characteristic of thalassaemias?

    <p>Hereditary abnormal hemoglobin production</p> Signup and view all the answers

    What is the primary function of platelets in haemostasis?

    <p>Facilitate coagulation and form a fibrin clot</p> Signup and view all the answers

    Which component is essential for the coagulation phase of haemostasis?

    <p>Calcium</p> Signup and view all the answers

    Which pathway of coagulation is primarily activated by tissue injury?

    <p>Extrinsic pathway</p> Signup and view all the answers

    What is the role of fibrinolysis in the body?

    <p>Dissolution of clots after they are no longer needed</p> Signup and view all the answers

    Which of the following statements about the ABO blood group system is true?

    <p>Blood group A has anti-B antibodies</p> Signup and view all the answers

    How are platelets produced in the body?

    <p>From megakaryocytes in the bone marrow</p> Signup and view all the answers

    In which condition is there an increased risk of hemorrhage due to inadequate clotting?

    <p>Thrombocytopenia</p> Signup and view all the answers

    What is a characteristic feature of fibrin clots?

    <p>They provide a temporary matrix for healing</p> Signup and view all the answers

    What is the primary consequence of a Rh negative mother having an Rh positive baby during pregnancy?

    <p>Haemolytic disease of the newborn</p> Signup and view all the answers

    Which blood group is considered the universal donor in emergencies?

    <p>O-</p> Signup and view all the answers

    What role do platelets play in the process of haemostasis?

    <p>Formation of a stable fibrin clot</p> Signup and view all the answers

    How is coagulation primarily controlled in the body?

    <p>Via calcium and vitamin K</p> Signup and view all the answers

    Which of the following statements about haemostasis is correct?

    <p>It involves a series of biochemical reactions to form fibrin clots.</p> Signup and view all the answers

    What is the main structure responsible for the clotting process in the blood?

    <p>Platelets</p> Signup and view all the answers

    Which of the following groups can receive blood from a Rh positive donor?

    <p>Rh positive individuals</p> Signup and view all the answers

    Which component is produced in response to the need for clotting after a vascular injury?

    <p>Fibrinogen</p> Signup and view all the answers

    Which component is produced during the coagulation phase that helps stabilize the fibrin clot?

    <p>Factor XIII</p> Signup and view all the answers

    What role does calcium play in the clotting process?

    <p>Supports the formation of thrombin</p> Signup and view all the answers

    Which blood group system is primarily determined by the presence of specific antigens on red blood cells?

    <p>ABO system</p> Signup and view all the answers

    What initiates the extrinsic pathway of coagulation?

    <p>Tissue factor binding to Factor VII</p> Signup and view all the answers

    Which of the following accurately describes platelets?

    <p>Produced by megakaryocytes and lack a nucleus</p> Signup and view all the answers

    What is the primary enzyme involved in the process of fibrinolysis?

    <p>Plasmin</p> Signup and view all the answers

    Which vitamin is necessary for the production of certain clotting factors in the liver?

    <p>Vitamin K</p> Signup and view all the answers

    During which phase of haemostasis does vasoconstriction occur?

    <p>Vasoconstrictor phase</p> Signup and view all the answers

    Which of the following is a consequence of decreased platelet numbers?

    <p>Impaired haemostasis</p> Signup and view all the answers

    What is a characteristic aspect of the intrinsic pathway in coagulation?

    <p>Involves Factor XI and co-factor VIII</p> Signup and view all the answers

    What is the final product formed when thrombin acts on fibrinogen during coagulation?

    <p>Stable fibrin clot</p> Signup and view all the answers

    Which factor is involved in the stabilization of fibrin during the coagulation process?

    <p>Factor XIII</p> Signup and view all the answers

    Which type of blood group is characterized as recessive within the ABO system?

    <p>O</p> Signup and view all the answers

    What is the primary function of antithrombin in blood clotting control?

    <p>Inhibits thrombin activity</p> Signup and view all the answers

    Which of the following best describes the primary function of lymphocytes in the immune system?

    <p>Central role in immunological defense mechanisms</p> Signup and view all the answers

    Which white blood cell type is primarily involved in mediating allergic responses and fighting parasitic infections?

    <p>Eosinophil</p> Signup and view all the answers

    Basophils release histamine and heparin during the inflammatory response. What is their main function?

    <p>To mediate inflammatory responses</p> Signup and view all the answers

    What is the typical lifespan of monocytes in the blood before they migrate to tissues?

    <p>3-4 days</p> Signup and view all the answers

    Which of the following white blood cells is least common in the bloodstream?

    <p>Basophil</p> Signup and view all the answers

    What is the main characteristic that distinguishes neutrophils from other types of white blood cells?

    <p>Phagocytic ability</p> Signup and view all the answers

    Which type of lymphocyte is primarily responsible for humoral immunity?

    <p>B cells</p> Signup and view all the answers

    How do platelets contribute to hemostasis?

    <p>By aggregating and sealing wounds</p> Signup and view all the answers

    Which type of white blood cells comprises approximately 50-70% of the total WBC count?

    <p>Neutrophils</p> Signup and view all the answers

    What distinguishes granulocytes from agranulocytes?

    <p>Granulocytes have a nucleus with multiple lobes.</p> Signup and view all the answers

    Which of the following cells is primarily responsible for phagocytosis?

    <p>Neutrophils</p> Signup and view all the answers

    How long do neutrophils typically circulate in the bloodstream before migrating to tissues?

    <p>10 hours</p> Signup and view all the answers

    Which type of white blood cell is best known for its role in combating parasitic infections?

    <p>Eosinophils</p> Signup and view all the answers

    What is the normal white blood cell count range for adults?

    <p>4-11 x 10^9 /litre</p> Signup and view all the answers

    What process describes the migration of white blood cells out of the bloodstream into tissues?

    <p>Extravasation</p> Signup and view all the answers

    Which characteristic of monocytes differentiates them from other types of white blood cells?

    <p>They survive for several months in tissues.</p> Signup and view all the answers

    Study Notes

    Blood Composition and Components

    • Blood is approximately 55% plasma (range 46-63%)
    • Plasma is mainly water (92%), with proteins (7%) including albumin, globulins, fibrinogen, and regulatory proteins.
    • Other solutes (1%) include electrolytes, organic nutrients, and waste products.
    • Blood also contains formed elements: red blood cells (45%), white blood cells and platelets (<1%)

    Blood Functions

    • Transport of inorganic and organic molecules, formed elements, and heat.
    • Transport of gases (O2 and CO2), nutrients, excretory products (waste), and temperature regulation.
    • Defence through antibodies and white blood cells, and clotting factors.

    Blood Cell Production (Hematopoiesis)

    • Hematopoiesis is the formation of blood cells.
    • Multipotential hematopoietic stem cells (Hemocytoblasts) are the precursor cells of all blood cells.
    • The Common Myeloid Progenitor produces erythrocytes, megakaryocytes and granulocytes.
    • The Common Lymphoid Progenitor produces lymphocytes and natural killer cells.

    Erythropoiesis (Red Blood Cell Production)

    • Erythropoiesis is the production of red blood cells, crucial for oxygen transport.
    • Requirements for Erythropoiesis include: Erythropoietin (EPO), iron, vitamins B12 & folic acid, intrinsic factor, and amino acids.
    • Erythropoiesis occurs in the yolk sac (fetus), then in the liver and spleen (fetus), and finally in the bone marrow (infant and adult), with different locations playing varying roles at different stages.
    • Rate of production is approximately 2-3 million red blood cells per second.

    Red Blood Cell Structure and Function

    • Red blood cells (erythrocytes) are biconcave discs, flexible to pass through narrow capillaries.
    • They are anucleate (lack a nucleus), lacking organelles, and filled primarily with haemoglobin .
    •  Haemoglobin carries oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the lungs, facilitating gas exchange.

    Red Blood Cell Breakdown and Recycling

    • Aged or damaged red blood cells are broken down by macrophages in the spleen and liver, essential for maintaining homeostasis.
    • Haemoglobin is broken down into heme (and then biliverdin) and the globin chain.
    • Iron is salvaged and stored in the spleen; bilirubin is secreted into the bile.

    Erythrocyte Homeostasis

    • Erythropoiesis is regulated by the amount of oxygen in the blood.
    • When oxygen levels drop (hypoxia), the kidneys release erythropoietin (EPO) stimulating red blood cell production in the bone marrow, maintaining a balance.

    Haemoglobin (Hb)

    • Haemoglobin is a protein in red blood cells, which binds to oxygen.
    • Approximately 280 million Hb molecules per red blood cell.
    • Synthesis begins in the proerythroblast, 65% is completed by the erythroblast stage and final 35% during the reticulocyte stage.
    • Hb carries oxygen from lungs to tissues and carbon dioxide from tissues to lungs, facilitating the transport of these vital substances throughout the body.
    • Normal blood Hb levels are approximately 12-16 g/dL for females and 13.5-17.5 g/dL for males.

    Adult Haemoglobin (HbA)

    • Composed of 4 subunits: 2 alpha (α) and 2 beta (β) subunits.
    • Each subunit contains a "haem" group which is a ferrous iron atom (Fe²⁺) able to bind to oxygen reversibly, crucial for oxygen transport.

    Anemia

    • Anemia is defined as a condition where haemoglobin concentration in blood falls below normal levels, leading to various symptoms.
    • Types of anemia include:
      • Iron deficiency anemia
      • Megaloblastic anemia (e.g, vitamin B12 deficiency, folate deficiency)
      • Sickle cell anemia
      • Thalassemias

    Iron Deficiency Anemia

    • Most common type of anemia worldwide.
    • Characterized by hypochromic and microcytic red blood cells (reduced Hb content and smaller size).
    • Causes include pregnancy, blood loss, dietary deficiencies, and others, like malabsorption issues.
    • Diagnosis of iron deficiency anemia involves identifying the cause as proper treatment requires addressing underlying issues.

    Megaloblastic Anemia

    • Can be due to vitamin B12 or folate deficiency, causing issues with red blood cell division and growth factors.
    • Characterized by macrocytic red blood cells (larger size) and abnormalities during mitosis.
    • Causes involve issues with red blood cell division, dietary insufficiencies, or inadequate intrinsic factor.
    • Vitamin B12 deficiency can also result in pernicious anemia where an intrinsic factor is lacking, impacting vitamin B12 absorption. 

    Sickle Cell Anemia

    • Hereditary blood disorder (typically African or West Indian descent) causing abnormal hemoglobin structure.
    • Abnormal haemoglobin causes red blood cells to change shape (sickle shape) which can get stuck in blood vessels leading to issues, necessitating ongoing care.

    Thalassemias

    • Hereditary blood disorder (typically Mediterranean, Middle/Far Eastern descent).
    • Abnormal haemoglobin production leading to abnormal red blood cell shape, typically smaller size.

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    Description

    This quiz explores the composition and functions of blood, including the roles of plasma, formed elements, and the process of hematopoiesis. Test your knowledge on how blood transports various substances, provides defense, and regulates body temperature.

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