Blood Composition and Functions
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Blood Composition and Functions

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Questions and Answers

What is the primary role of erythrocytes in the blood?

  • O2 and CO2 exchange (correct)
  • Transporting hormones
  • Stoppage of bleeding
  • Fighting infections
  • Which component constitutes the largest percentage of blood?

  • Leukocytes
  • Erythrocytes
  • Platelets
  • Plasma (correct)
  • What is the function of leukocytes in blood?

  • Transporting nutrients
  • Fighting against infections (correct)
  • Regulating body temperature
  • Maintaining osmotic pressure
  • What percentage of blood volume is made up by formed elements?

    <p>45%</p> Signup and view all the answers

    Which of the following proteins contributes the least to plasma composition?

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

    What is the primary function of thrombocytes in the blood?

    <p>Facilitating blood clotting</p> Signup and view all the answers

    What percentage of blood plasma is composed of water?

    <p>91%</p> Signup and view all the answers

    Which plasma protein is primarily responsible for maintaining colloidal osmotic pressure?

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

    What causes a decrease in the albumin/globulin (A/G) ratio?

    <p>Infection leading to higher globulin levels</p> Signup and view all the answers

    What is the average lifespan of red blood corpuscles (erythrocytes)?

    <p>120 days</p> Signup and view all the answers

    Which ion is primarily found inside red blood cells?

    <p>Potassium (K+)</p> Signup and view all the answers

    Which plasma protein is involved in blood clotting and contributes to plasma viscosity?

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

    What is the concentration of prothrombin in blood plasma?

    <p>10 mg/100 ml</p> Signup and view all the answers

    What is the typical red blood cell count in adult males?

    <p>5-6 million per cubic mm</p> Signup and view all the answers

    Which function is NOT performed by hemoglobin in red blood cells?

    <p>Facilitate the breakdown of glucose</p> Signup and view all the answers

    What is the primary site of red blood cell formation after the age of 20?

    <p>Membranous bones</p> Signup and view all the answers

    What is the average lifespan of a red blood cell?

    <p>120 days</p> Signup and view all the answers

    Which component of red blood cells allows them to change shape when passing through capillaries?

    <p>Plastic nature of the membrane</p> Signup and view all the answers

    Which of the following is a consequence of hemoglobin remaining in the bloodstream?

    <p>Potential heart failure</p> Signup and view all the answers

    What specific role does carbonic anhydrase play in red blood cells?

    <p>Assist in carbon dioxide transport</p> Signup and view all the answers

    Which factor is crucial for maintaining normal red blood cell counts?

    <p>Rate of erythropoiesis equal to destruction</p> Signup and view all the answers

    What role does the liver play in erythropoiesis?

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

    Which type of anemia results from bone marrow depression?

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

    What is a common cause of microcytic hypochromic anemia?

    <p>Iron deficiency due to poor diet</p> Signup and view all the answers

    What is a primary feature of macrocytic (megaloblastic) anemia?

    <p>Deficiency of folic acid or Vitamin B12</p> Signup and view all the answers

    What is a consequence of renal failure related to anemia?

    <p>Reduced production of erythropoietin</p> Signup and view all the answers

    Which organ secretes the majority of erythropoietin hormone?

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

    What is required for the absorption of Vitamin B12 from the stomach?

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

    Which of the following conditions could lead to haemolytic anemia?

    <p>Incompatible blood transfusion</p> Signup and view all the answers

    Which condition does NOT lead to hypoxia?

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

    What stimulates the production of erythropoietin in response to hypoxia?

    <p>Kidney response</p> Signup and view all the answers

    Which form of iron is better absorbed in the body?

    <p>Ferrous iron</p> Signup and view all the answers

    What role does intrinsic factor play in the absorption of Vitamin B12?

    <p>It protects Vitamin B12 from gastric digestion.</p> Signup and view all the answers

    Which vitamin is essential for the myelination of nerves?

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

    What dietary component can prevent the absorption of iron?

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

    What hormone is specifically responsible for stimulating red blood cell production?

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

    Which trace element acts as a cofactor in hemoglobin formation?

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

    Study Notes

    Blood

    • Vital fluid tissue that circulates inside blood vessels
    • Represents 8% of body weight, or 5.6 liters

    Functions of blood

    • Transport function: Transports oxygen, carbon dioxide, nutrients, waste products, and hormones.
    • Defensive function: Contains white blood cells and antibodies.
    • Hemostasis: Stops bleeding.
    • Homeostasis: Maintains the internal environment (extracellular fluid) of the body for optimal cell function.

    Composition of blood

    • Plasma:
      • 55% of blood by volume and weight.
      • Contains water, proteins (albumin, globulins, fibrinogen, prothrombin), and other solutes like ions, nutrients, waste products, gases, and regulatory substances.
    • Formed Elements:
      • 45% of blood by volume and weight.
      • Contains leukocytes, platelets, and erythrocytes.

    Leukocytes

    • Less than 1% of blood cell count.
    • Includes neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

    Platelets

    • Less than 1% of blood cell count.
    • Involved in blood clotting.

    Erythrocytes

    • More than 99% of blood cell count.
    • Non-nucleated circular biconcave discs containing hemoglobin, responsible for oxygen and carbon dioxide exchange.
    • Average lifespan of 120 days.

    Blood Plasma

    • Yellow clear fluid consisting of water, proteins, and other substances.
    • Plays a crucial role in maintaining blood volume and pressure, and transporting nutrients and waste products.

    Plasma Proteins

    • Albumin: Highest concentration, important for maintaining colloidal osmotic pressure and transporting substances.
    • Globulins: Function in defense (α, β, γ globulins) and transport of certain substances.
    • Fibrinogen: Essential for blood clotting and contributes to plasma viscosity.
    • Prothrombin: Important for blood clotting.

    Albumin/Globulin (A/G) Ratio

    • The ratio of albumin to globulin concentration in the blood is between 1.2 and 1.7.
    • Decreased A/G ratio can be observed in:
      • Liver disease due to decreased albumin production.
      • Kidney disease due to loss of albumin through urine.
      • Infection due to an increase in globulin concentration.

    Red Blood Cells (Erythrocytes)

    • Non-nucleated, circular, biconcave discs containing hemoglobin.
    • Responsible for oxygen and carbon dioxide transport.
    • Contain carbonic anhydrase enzyme and glucose-6-phosphate dehydrogenase (G-6-PD).

    Red Blood Cell Count

    • Adult males: 5-6 million per cubic mm.
    • Adult females: 4-5 million per cubic mm.
    • Newborns: 7 million per cubic mm.

    Functions of Red Blood Cells

    • Carry oxygen to tissues and remove carbon dioxide.
    • Hemoglobin acts as a blood buffer.
    • Red blood cells contain carbonic anhydrase, important for carbon dioxide transportation.
    • The biconcave shape of red blood cells increases surface area, facilitating gas exchange.

    Erythrocyte Membrane

    • Keeps hemoglobin inside, preventing heart failure, increased blood viscosity, and renal failure.
    • Contains agglutinogens that determine blood group.
    • The plastic nature allows red blood cells to compress while passing through narrow capillaries and regain their normal shape after, preventing rupture.

    Formation of Red Blood Cells (Erythropoiesis)

    • Fetus: Formed in the liver and spleen.
    • Last three months of fetal life and after birth: Formed in the bone marrow of all bones until adolescence.
    • Age 20: Formed in the bone marrow of the upper parts of the humerus and femur and of membranous bones.
    • After age 20: Formed in the bone marrow of membranous bones (skull, vertebra, sternum, and ribs).

    Factors Affecting Erythropoiesis

    • Oxygen Supply to Tissues: Hypoxia stimulates the release of erythropoietin hormone, primarily from the kidney, which increases red blood cell production.
    • Diet:
      • Proteins: Provide essential amino acids for globin formation in hemoglobin.
      • Iron: Crucial for hemoglobin synthesis, and its absorption is influenced by factors like gastric acid, vitamin C, and the presence of substances like oxalates, phytic acids, and phosphates.
      • Vitamins:
        • Vitamin B12: Essential for red blood cell nuclear maturation, cell division, myelination of nerves, and digestive system mucosa integrity.
        • Folic Acid: Necessary for red blood cell nuclear maturation and cell division.
        • Vitamin C: Promotes tissue growth and metabolism, including bone marrow.
      • Trace Elements: Copper and cobalt act as cofactors for hemoglobin formation.
      • Hormones: Erythropoietin (specific), thyroid hormones (non-specific), and male sex hormones (androgen) promote erythropoiesis.
    • Healthy Organs:
      • Bone Marrow: Site of red blood cell formation.
      • Liver: Plays a role in erythropoiesis, producing globin for hemoglobin, secreting erythropoietin, and storing iron and Vitamin B12.
      • Kidney: Secretes the majority of erythropoietin in response to hypoxia.
      • Stomach: Produces gastric HCl which is essential for iron conversion, and secretes intrinsic factor for vitamin B12 absorption.
      • Small Intestine: Site of iron and vitamin B12 absorption.

    Anemia

    • A condition characterized by a decrease in red blood cell count or hemoglobin content, or both.

    Types and Causes of Anemia

    • Normochromic Normocytic Anemia

      • Haemolytic Anemia: Caused by excessive destruction of red blood cells due to factors like incompatible blood transfusions, snake venoms, drug sensitivity, infections, antibodies, and increased red blood cell fragility.
      • Aplastic Anemia: Due to bone marrow depression, caused by radiation exposure, chemotherapy, drugs, or bone marrow destruction.
      • Haemorrhagic Anemia: Occurs due to acute blood loss.
    • Microcytic Hypochromic Anemia

      • Iron Deficiency Anemia: Caused by either iron deficiency in the diet, failure of iron absorption, or chronic blood loss.
    • Macrocytic (Megaloblastic) Anemia

      • Caused by deficiency of vitamin B12 or folic acid.

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