PHGY 209 Midterm blood
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Questions and Answers

What defines a non-penetrating solute in the context of tonicity?

  • A solute that has a high permeability to the cell membrane.
  • A solute that can facilitate movement of water through the membrane.
  • A solute that does not move across the membrane, allowing only fluid to pass. (correct)
  • A solute that can freely cross the cell membrane.

    • Which ions are mentioned as being 'leaky' but still considered non-penetrating?

  • Cl- and HCO3-
  • Na+ and K+ (correct)
  • Ca2+ and Cl-
  • Mg2+ and H+

    • What is the osmolarity of body fluids as indicated in the content?

  • 400 mOsm
  • 500 mOsm
  • 200 mOsm
  • 300 mOsm (correct)

    • Which statement best describes the role of the Na+/K+ ATPase in relation to tonicity?

    <p>It pumps Na+ and K+ back out, maintaining their status as non-penetrating solutes.</p> Signup and view all the answers

    How does tonicity affect the process of osmosis across a cell membrane?

    <p>It selectively allows water to move while preventing solute movement.</p> Signup and view all the answers

    What occurs to a hypotonic cell in relation to its osmolarity?

    <p>It swells as water moves into the cell.</p> Signup and view all the answers

    In an isosmotic solution, what is the effect on an isotonic cell?

    <p>There is no net movement of water in or out of the cell.</p> Signup and view all the answers

    What is the consequence of placing a hypertonic cell in a hypertonic solution?

    <p>The cell shrinks as water leaves the cell.</p> Signup and view all the answers

    Which osmolarity level represents a hypotonic cell?

    <p>250 mOsm</p> Signup and view all the answers

    What can also cause swelling in a cell aside from being hypotonic?

    <p>A hyperosmotic solution greater than 300 mOsm.</p> Signup and view all the answers

    What type of cells do hematopoietic stem cells give rise to?

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

    Which of the following processes specifically refers to the formation of red blood cells?

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

    What characterizes the nature of bone marrow cells?

    <p>They are multipotent or pluripotent stem cells.</p> Signup and view all the answers

    From which progenitor cells do platelets arise?

    <p>Myeloid progenitor cells</p> Signup and view all the answers

    Which cell type is NOT a product of hematopoiesis?

    <p>Cardiac muscle cells</p> Signup and view all the answers

    In which anatomical locations do fetuses primarily produce blood?

    <p>Yolk sac, liver, and spleen</p> Signup and view all the answers

    Which locations are involved in blood production for children?

    <p>Long bones and axial skeleton bones</p> Signup and view all the answers

    Where does blood production occur in adults?

    <p>Axial skeleton bones</p> Signup and view all the answers

    What is the order of blood production sites from fetus to adult?

    <p>Yolk sac, liver/spleen, axial skeleton</p> Signup and view all the answers

    What is the primary function of cytokines like hematopoietic growth factors (HGFs)?

    <p>They impact the activity of neighboring cells.</p> Signup and view all the answers

    Which type of cells do hematopoietic growth factors primarily influence?

    <p>Bone marrow stem cells</p> Signup and view all the answers

    What occurs when cytokines such as hematopoietic growth factors are released by one cell?

    <p>They stimulate growth, division, or development in another cell.</p> Signup and view all the answers

    In what way do hematopoietic growth factors affect bone marrow stem cells?

    <p>They influence their growth, division, or development.</p> Signup and view all the answers

    Which statement best describes cytokines in the context of cell communication?

    <p>They are signaling molecules that affect other cells' behavior.</p> Signup and view all the answers

    What is the primary gas transported by hemoglobin in red blood cells?

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

    Which component of red blood cells helps to regulate blood pH?

    <p>Carbonic anhydrase</p> Signup and view all the answers

    What is the primary shape of mature red blood cells?

    <p>Biconcave disk</p> Signup and view all the answers

    What happens to the number of red blood cells when the oxygen levels in the body decrease?

    <p>It increases to meet oxygen needs</p> Signup and view all the answers

    Why is the presence of spectrin important for red blood cells?

    <p>It enhances flexibility and surface area for diffusion</p> Signup and view all the answers

    What is the maximum number of oxygen molecules a single red blood cell can carry?

    <p>4 molecules</p> Signup and view all the answers

    Which factor increases the binding affinity of hemoglobin for oxygen?

    <p>Lower pCO2 levels</p> Signup and view all the answers

    What is the approximate volume of oxygen transported by hemoglobin in 100 mL of blood, given an average hemoglobin level of 15 g/100 mL?

    <p>20 mL O2</p> Signup and view all the answers

    Which statement about the plasma's oxygen content is true?

    <p>Plasma holds 0.3% O2 dissolved gas.</p> Signup and view all the answers

    What is the molecular weight of hemoglobin?

    <p>64 kDa</p> Signup and view all the answers

    How much oxygen can fully saturated hemoglobin carry per gram of hemoglobin?

    <p>1.34 mL O2</p> Signup and view all the answers

    What effect does an increase in temperature have on hemoglobin's oxygen binding?

    <p>Decreases binding affinity</p> Signup and view all the answers

    How many grams of hemoglobin are typically found in 100 mL of blood for men?

    <p>16 g/100 mL</p> Signup and view all the answers

    What is the percentage of bound oxygen volume in oxyhemoglobin?

    <p>19.5%</p> Signup and view all the answers

    What triggers the release of erythropoietin (EPO) in the body?

    <p>Low oxygen availability</p> Signup and view all the answers

    Which hormone decreases the sensitivity of stem cells to erythropoietin (EPO)?

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

    For how long does erythropoiesis last due to the action of erythropoietin (EPO) on myeloid stem cells?

    <p>3-5 days</p> Signup and view all the answers

    What is the role of the negative feedback loop in erythropoiesis?

    <p>To inhibit EPO production when oxygen levels are high</p> Signup and view all the answers

    Why do men generally have higher red blood cell counts compared to women?

    <p>Higher levels of testosterone stimulating RBC production</p> Signup and view all the answers

    Which developmental stage follows the transition from pluripotent stem cells?

    <p>Myeloid stem cell progenitor cells</p> Signup and view all the answers

    What is the size reduction observed in proerythroblasts as they mature into reticulocytes?

    <p>From 18 to 7 um</p> Signup and view all the answers

    Which characteristic describes reticulocytes at the time of their formation?

    <p>They are still nucleated.</p> Signup and view all the answers

    What key process occurs in reticulocytes during their development?

    <p>Accumulation of hemoglobin and loss of organelles</p> Signup and view all the answers

    How long does it typically take for reticulocytes to be formed after the initial stem cell differentiation?

    <p>3-5 days</p> Signup and view all the answers

    What is the primary role of macrophages in relation to red blood cells?

    <p>They remove old RBCs from circulation.</p> Signup and view all the answers

    How is iron stored in the body following the breakdown of red blood cells?

    <p>Bound to transferrin and stored with ferritin.</p> Signup and view all the answers

    What condition results from bilirubin exceeding 1 mg/dL in blood plasma?

    <p>Jaundice.</p> Signup and view all the answers

    In newborns, why might hemolysis lead to an increase in bilirubin levels?

    <p>Because of excess RBCs during development.</p> Signup and view all the answers

    Which factor can contribute to jaundice by impairing bilirubin excretion?

    <p>Liver disease.</p> Signup and view all the answers

    What defines absolute polycythemia?

    <p>Increased RBC production due to pathological conditions</p> Signup and view all the answers

    Which of the following scenarios could lead to secondary polycythemia?

    <p>Can result from chronic lung disease</p> Signup and view all the answers

    What consequence may arise from an excess of red blood cells in the bloodstream?

    <p>Higher risk of blood clots</p> Signup and view all the answers

    Relative polycythemia is typically associated with which condition?

    <p>Dehydration and temporary fluid loss</p> Signup and view all the answers

    Which of the following is NOT a possible factor leading to increased red blood cell production?

    <p>Sun exposure</p> Signup and view all the answers

    What is the primary role of erythropoietin (EPO) in the body?

    <p>Promotes the production of red blood cells</p> Signup and view all the answers

    What is the main function of macrophages concerning red blood cells?

    <p>To break down and recycle hemoglobin from aged red blood cells</p> Signup and view all the answers

    Which characteristic is typical of reticulocytes at the time of their formation?

    <p>They contain a significant amount of ribosomal RNA.</p> Signup and view all the answers

    What triggers the release of erythropoietin (EPO) in the body?

    <p>Decreased oxygen levels in the blood</p> Signup and view all the answers

    How does the binding affinity of hemoglobin for oxygen change with an increase in temperature?

    <p>It decreases, facilitating oxygen release to tissues.</p> Signup and view all the answers

    What defines the morphological classification of anemia?

    <p>Changes in red blood cell (RBC) size and color</p> Signup and view all the answers

    Which term describes red blood cells that exhibit an excess of hemoglobin?

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

    What characterizes microcytic red blood cells?

    <p>Smaller than normal in size</p> Signup and view all the answers

    Which option accurately describes normocytic red blood cells?

    <p>They maintain a normal size but may vary in color</p> Signup and view all the answers

    What determines whether an anemia is classified as microcytic, normocytic, or macrocytic?

    <p>The size of the red blood cells</p> Signup and view all the answers

    What type of anemia is characterized by a lack of production by the bone marrow despite normal cell morphology?

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

    Which physiological condition can lead to stimulation failure anemia?

    <p>Chronic renal disease</p> Signup and view all the answers

    What is the typical daily dietary iron intake recommended to meet the body's needs?

    <p>15 mg</p> Signup and view all the answers

    During menstruation, how much iron is estimated to be lost per month due to blood loss?

    <p>50 mg</p> Signup and view all the answers

    Which type of anemia is specifically associated with microcytic and hypochromic red blood cells due to inadequate iron levels?

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

    What is a common consequence of deficiencies in B12 or folic acid?

    <p>Decreased DNA synthesis and RBC maturation</p> Signup and view all the answers

    What condition is characterized by increased RBC destruction or reduced RBC lifespan?

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

    Which of the following can lead to the development of pernicious anemia?

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

    Which abnormality is associated with spherocytosis in RBCs?

    <p>Abnormal RBC membrane structure</p> Signup and view all the answers

    Which factor can contribute to acquired hemolytic anemia?

    <p>Autoimmune diseases</p> Signup and view all the answers

    What initiates primary hemostasis at a vascular injury site?

    <p>Vasoconstriction and platelet adhesion</p> Signup and view all the answers

    Which of the following substances is released by platelets to enhance their stickiness?

    <p>Thromboxane A2 (TXA2)</p> Signup and view all the answers

    What is the net result of the primary hemostatic process?

    <p>Aggregation of platelets forming a white thrombus</p> Signup and view all the answers

    Which component facilitates the adherence of platelets to collagen at the injury site?

    <p>Von Willebrand factor</p> Signup and view all the answers

    What occurs during the vascular response in hemostasis?

    <p>Vasoconstriction and decreased blood flow</p> Signup and view all the answers

    What initiates the process of primary hemostasis immediately after an injury?

    <p>Vascular response through vasoconstriction</p> Signup and view all the answers

    Which factor is responsible for the adherence of platelets to the exposed collagen at the injury site?

    <p>Von Willebrand factor</p> Signup and view all the answers

    What stabilizes the aggregation of platelets at the injury site during primary hemostasis?

    <p>Consolidation of platelets with fibrin</p> Signup and view all the answers

    What is the main role of thromboxane A2 in primary hemostasis?

    <p>Increasing platelet stickiness</p> Signup and view all the answers

    Which of the following substances is released by platelets to further decrease blood flow at the injury site?

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

    What triggers the activation of the coagulation pathway during blood clot formation?

    <p>The formation of a white thrombus platelet plug</p> Signup and view all the answers

    In the coagulation process, what role do calcium ions play?

    <p>They serve as essential cofactors for various reactions.</p> Signup and view all the answers

    What components are primarily involved in the formation of blood clots?

    <p>Plasma proteins, calcium, and phospholipid agents</p> Signup and view all the answers

    What is the primary role of plasma proteins and clotting factors in blood clot formation?

    <p>To act as enzymes or cofactors in coagulation</p> Signup and view all the answers

    What type of thrombus is formed after the initial platelet plug (white trombus) during hemostasis?

    <p>Red thrombus</p> Signup and view all the answers

    What role does thrombin play in the intrinsic pathway of blood coagulation?

    <p>It acts as a positive regulator.</p> Signup and view all the answers

    Which component is NOT considered a cofactor for prothrombinase activation in the intrinsic pathway?

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

    What initiates the activation of the extrinsic pathway of blood coagulation?

    <p>Trauma to blood vessels</p> Signup and view all the answers

    Which substances are released by endothelial cells to aid in the response to damage?

    <p>Vasodilators like nitric oxide and prostacyclin</p> Signup and view all the answers

    What is the final pathway that both the intrinsic and extrinsic pathways of blood coagulation lead to?

    <p>Activation of prothrombinase</p> Signup and view all the answers

    What is the role of Vitamin K in the synthesis of certain blood factors?

    <p>It acts as a cofactor for the synthesis of prothrombin and other factors.</p> Signup and view all the answers

    Which of the following conditions can lead to acquired multi-factor deficiencies in clotting?

    <p>Liver disease</p> Signup and view all the answers

    Which clotting factor is synthesized with the help of Vitamin K?

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

    What can result from Vitamin K deficiency in the body?

    <p>Increased risk of bleeding disorders</p> Signup and view all the answers

    Which statement accurately describes acquired multi-factor deficiencies?

    <p>They can occur due to inadequate dietary intake of Vitamin K.</p> Signup and view all the answers

    What is the function of thrombosthenin released by platelets in the clot retraction process?

    <p>To shrink the clot by forcing fluid out</p> Signup and view all the answers

    Which medical drug specifically inhibits platelet adhesion?

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

    Which of the following statements about anticoagulants is accurate?

    <p>They block components in the clotting pathway.</p> Signup and view all the answers

    What is the role of t-PA in relation to clot management?

    <p>To facilitate clot lysis</p> Signup and view all the answers

    Which compound is specifically blocked by Coumarin, impacting the synthesis of clotting factors?

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

    What is the function of plasminogen activators in clot lysis?

    <p>Convert plasminogen to plasmin</p> Signup and view all the answers

    Which of the following are intrinsic proactivators in the clot lysis process?

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

    What type of proactivators are tissue factors categorized as?

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

    Which process describes the breakdown of clots in the body?

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

    What is produced when plasminogen is activated?

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

    What condition is characterized by small red or purple spots due to bleeding into the skin?

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

    Which cytokine is produced by the liver and is involved in platelet production?

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

    What is a consequence of platelet dysfunction?

    <p>Lack of clotting factors</p> Signup and view all the answers

    What does thrombocytopenia indicate in relation to platelets?

    <p>Low platelet count</p> Signup and view all the answers

    Loss of vascular integrity can lead to which of the following?

    <p>Uncontrolled bleeding</p> Signup and view all the answers

    Study Notes

    Tonicity

    • Tonicity describes a solution's ability to cause osmosis across a cell membrane.
    • This occurs when a non-penetrating solute cannot cross the membrane, allowing only fluid movement.
    • While some ions like Na+ or K+ can leak across the membrane, they are considered non-penetrating because the Na+/K+ ATPase pump actively transports them back out.
    • The typical osmolarity of body fluids is 300 mOsm.

    Isotonic Cells in Isosmotic Solution

    • No net movement of water into or out of the cell
    • Cells have the same osmolarity as body fluids
    • Osmolarity is 300 mOsm, which translates to 6.7 atm or 5100 mmHg

    Hypotonic Cells

    • Cells have lower osmolarity than body fluids
    • Water moves into the cell, causing swelling.
    • This occurs because the cell has a lower concentration of solutes than the surrounding fluid.

    Hypertonic Cells

    • Cells have a higher osmolarity than body fluids
    • Water moves out of the cell, causing shrinkage
    • This occurs because the cell has a higher concentration of solutes than the surrounding fluid.

    Hematopoiesis

    • Hematopoiesis is the process of blood cell formation
    • Hematopoietic stem cells (HSCs) give rise to all blood cells including red blood cells (RBCs), white blood cells (WBCs), and platelets.
    • HSCs are also known as blood progenitor cells or bone marrow cells.
    • HSCs are pluripotent, meaning they can differentiate into multiple cell types.
    • HSCs divide into two main lineages: myeloid progenitor cells and lymphoid progenitor cells.
    • Myeloid progenitor cells differentiate into RBCs, platelets, and some types of WBCs.
    • Lymphoid progenitor cells differentiate into other types of WBCs, specifically lymphocytes.
    • Erythropoiesis is the process of RBC production.
    • Leukopoiesis is the process of WBC production.
    • Thrombopoiesis is the process of platelet production.

    Cytokines

    • Cytokines are substances released by cells that influence the activity of other cells.
    • These activities can include growth, division, or development.
    • One example of cytokines is hematopoietic growth factors (HGFs).
    • HGFs specifically influence the activities of bone marrow stem cells.

    Non-Penetrating Solutes

    • A non-penetrating solute is a substance that does not readily cross the cell membrane.

    • Leaky ions, like potassium (K+) and chloride (Cl-), are considered non-penetrating because they pass over the membrane at a slower rate than water does, despite them being able to cross.

    Osmolarity of Body Fluids

    • The osmolarity of body fluids is approximately 280-300 mOsm/L.

    Role of Na+/K+ ATPase in Tonicity

    • The Na+/K+ ATPase pump actively transports sodium (Na+) out of the cell and potassium (K+) into the cell, maintaining a concentration gradient and impacting the cell's tonicity.

    Tonicity and Osmosis

    • Tonicity refers to the effect of a solution on the volume of a cell due to osmosis.

    • Osmosis describes the movement of water across a semipermeable membrane from an area of high water concentration to low concentration.

    • Hypotonic solutions cause water to move into the cell, resulting in swelling.

    • Isotonic solutions have the same osmolarity as the cell, so there is no net movement of water, and the cell remains unchanged.

    • Hypertonic solutions cause water to move out of the cell, resulting in shrinkage.

    Effects of Tonicity on Cells

    • A hypotonic cell has a lower osmolarity than its surrounding environment.

    • A hypotonic cell can swell due to water moving into the cell from a higher concentration in the external environment.

    • A cell in an isosmotic solution that is also isotonic will not experience any volume change because there is no net movement of water.

    • A hypertonic cell placed in a hypertonic solution will shrink due to water moving out of the cell.

    Cell Swelling

    • In addition to being hypotonic, a cell can swell due to active ion uptake that increases its internal osmolarity.

    Hematopoiesis

    • Hematopoietic stem cells give rise to all types of blood cells.

    • Erythropoiesis is the specific process of forming erythrocytes (red blood cells).

    • The bone marrow contains hematopoietic stem cells and is where blood cells are generated.

    • Megakaryocytes are the progenitor cells for platelets.

    • Epithelial cells are not a product of hematopoiesis.

    Blood Production Sites

    • In fetuses, blood production primarily occurs in the yolk sac, liver, and spleen.

    • In children, blood production occurs in the bone marrow of most bones.

    • In adults, blood production is concentrated in the bone marrow of specific bones, including mainly the vertebrae, ribs, sternum, skull, and pelvis.

    • The order of primary blood production sites from fetus to adult is: yolk sac → liver → spleen → bone marrow.

    • Blood production does not occur in the kidney.

    Red Blood Cells (Erythrocytes)

    • Transport oxygen and carbon dioxide via hemoglobin (Hb) protein, which occupies one-third of the cell's volume.
    • Mature red blood cells lack organelles and contain water, hemoglobin, lipids, ions, and proteins.
    • They generate ATP anaerobically through glycolysis.
    • Carbonic anhydrase facilitates the conversion of water and carbon dioxide to hydrogen ions and bicarbonate, increasing carbon dioxide transport to the lungs and buffering blood pH.
    • Red blood cell size can vary from microcytic (small) to normocytic to macrocytic (large).
    • The number of red blood cells is regulated by oxygen needs.
    • Increased red blood cell production occurs in response to decreased oxygen availability, such as during activity or at high altitudes.
    • This increase in red blood cells leads to an elevated hematocrit.
    • Red blood cells have a biconcave disk shape.
    • Irregularities in this shape can lead to sickled cells or spherocytes (round balls).
    • Spectrin, a fibrous cytoskeletal protein, forms a flexible network within the cell membrane, increasing the surface area to volume ratio, which maximizes diffusion rates by minimizing diffusion distances.
    • This flexibility allows red blood cells to squeeze through narrow capillary diameters.

    Hemoglobin Structure and Function

    • Hemoglobin (Hb) is a protein composed of four polypeptide chains (two alpha and two beta chains), each containing a heme group.
    • Heme contains iron, which binds oxygen to form oxyhemoglobin (HbO2).
    • Each red blood cell (RBC) contains approximately 200 million Hb molecules, allowing it to carry a maximum of four oxygen molecules.
    • The molecular weight of Hb is 64 kDa.

    Oxygen Transport

    • Red blood cells contribute significantly to oxygen transport in the blood.
    • The plasma contains only 0.3% dissolved oxygen, while HbO2 carries 19.5% of the blood's oxygen volume.
    • Arterial blood contains approximately 20% oxygen (20 mL/100 mL blood).
    • Hb's oxygen carrying capacity is 65 times greater than the plasma at a partial pressure of oxygen (PO2) of 100 mmHg.

    Hemoglobin Levels and Gender

    • Normal Hb levels vary slightly between genders:
      • Men: 16 g/100 mL blood
      • Women: 14 g/100 mL blood

    Oxygen Carrying Capacity

    • Fully saturated Hb can carry 1.34 mL of oxygen per gram of Hb.
    • The average Hb level of 15 g/100 mL blood results in an oxygen carrying capacity of 20 mL O2.

    Hemoglobin Color

    • Oxygenated Hb (HbO2) is bright red, while deoxygenated Hb is dark red.

    Factors Affecting Hemoglobin Binding

    • Temperature: Increased temperature decreases the binding of oxygen to Hb.
    • Ionic Composition: Changes in ionic composition can alter the shape of the Hb protein, affecting oxygen binding.
    • pH: H+ ions can bind to Hb, altering its shape and reducing oxygen binding.
    • pCO2: Carbon dioxide can bind to Hb at a different site, affecting oxygen binding.
    • Carbonic Anhydrase: This enzyme is located within red blood cells and plays a role in CO2 transport.

    Hemoglobin Structure and Function

    • Hemoglobin (Hb) is a protein found within red blood cells (RBCs) responsible for oxygen transport.
    • It consists of four polypeptide chains, two alpha and two beta chains, each containing a heme group.
    • Heme contains iron, which binds to oxygen, forming oxyhemoglobin (HbO2).
    • Hemoglobin has a molecular weight of 64 kDa and there are approximately 200 million Hb molecules per RBC.

    Hemoglobin's Role in Oxygen Transport

    • Oxyhemoglobin carries about 19.5% of the oxygen volume in arterial blood, representing about 20 mL of oxygen per 100 mL of blood.
    • Hemoglobin's ability to bind oxygen is significantly higher than plasma alone, allowing it to carry 65 times more oxygen at a partial pressure of oxygen (PO2) of 100 mmHg.
    • Men typically have higher hemoglobin levels (16 g/100 mL blood) compared to women (14 g/100 mL blood).
    • Each gram of fully saturated Hb can bind 1.34 mL of oxygen, meaning an average hemoglobin concentration of 15 g/100 mL blood can carry 20 mL of oxygen.

    Factors Affecting Hemoglobin Binding

    • Oxygen binding to hemoglobin is influenced by several factors:
      • Temperature: Increased temperature decreases oxygen binding.
      • Ionic composition: Alterations in ionic composition can change the shape of the hemoglobin protein, affecting oxygen binding.
      • pH: Changes in pH, specifically H+ concentration, can bind to hemoglobin, altering its shape and oxygen binding affinity.
    • Oxygenated hemoglobin (HbO2) is bright red, while deoxygenated hemoglobin (Hb) is dark red.

    Erythropoiesis (RBC Synthesis)

    • Millions of red blood cells (RBCs) are produced every second.
    • Erythropoietin (EPO) is a glycoprotein hormone/cytokine produced by the kidneys (renal cortex).
    • EPO stimulates myeloid stem cells for 3-5 days to produce RBCs.
    • EPO release is triggered by hypoxic conditions (low oxygen levels) due to:
      • Low RBC count from metabolic causes or accidents
      • Low oxygen availability at higher altitudes
      • Increased tissue oxygen demand during physical activity
    • EPO production follows a negative feedback loop to maintain homeostasis. Increased plasma oxygen levels following RBC production decrease EPO production.
    • Hormonal factors influence EPO production and RBC count:
      • Testosterone increases EPO release and stem cell sensitivity to EPO, leading to higher RBC counts in men.
      • Estrogen decreases EPO release and target cell sensitivity to EPO, resulting in lower RBC counts in women.

    Erythrocyte Development

    • Erythrocyte production begins with pluripotent stem cells differentiating into myeloid stem cell progenitor cells.
    • Myeloid stem cells then develop into proerythroblasts.
    • Proerythroblasts undergo a series of developmental stages characterized by:
      • Reduction in cell size, from 18 micrometers to 7 micrometers.
      • Accumulation of hemoglobin (Hb).
      • Loss of organelles and the nucleus.
    • Reticulocytes are formed after 3 to 5 days of development.
    • Reticulocytes still contain some residual RNA and are therefore nucleated.
    • Reticulocytes eventually lose their RNA and mature into fully functional erythrocytes.

    Red Blood Cell Breakdown

    • Red blood cells (RBCs) have a lifespan of 120 days.
    • RBCs lack organelles and cannot extend their lifespan.
    • Macrophages, immune cells in the liver and spleen, remove old RBCs from circulation.
    • Macrophages recycle RBC components:
      • Globin protein chains are broken down into amino acids.
      • Iron binds to transferrin, a carrier protein, for storage with ferritin in the liver, spleen, and gut.
      • Stored iron is released as needed.
      • Heme is broken down into bilirubin, which is processed by the liver and excreted in stool.
    • Normal bilirubin levels in blood plasma are 1 mg/dL, giving plasma its yellow color.
    • Jaundice occurs when bilirubin levels exceed 1 mg/dL due to excessive bilirubin.
    • Newborns have excess RBCs to accommodate oxygen delivery during development, leading to increased heme breakdown and potential bilirubin buildup.
    • Liver disease can impair bilirubin excretion, causing bilirubin buildup in the blood.
    • Other causes of jaundice include burns, bile duct obstruction (gallstones), and some infections.

    Polycythemia

    • Increased RBC count

    • 6 x 106 RBC/uL

    • 18g Hb/100mL blood plasma

    • Increased blood viscosity and slower blood flow
    • May lead to clots
    • Relative Polycythemia
      • Temporary condition
      • Caused by dehydration
    • Absolute Polycythemia
      • Primary effect of pathological condition
        • Tumours
          • Increased EPO
          • Increased bone marrow divisions
      • Secondary effect of physiological condition
        • Detecting O2 response
          • Increased O2 needs
          • Decreased O2 availability
      • Examples:
        • High altitude
        • Increased physical activity
        • Chronic lung disease
        • Heavy smoking

    ### Anemia Classification

    • Morphologic Anemia: Describes changes in the size and color of red blood cells (RBCs), indicating potential underlying issues with the production or structure of the RBCs.
      • Size:
        • Microcytic: Smaller than normal RBCs.
        • Normocytic: Normal sized RBCs.
        • Macrocytic: Larger than normal RBCs.
      • Color:
        • Hypochromic: RBCs with a paler color due to reduced hemoglobin (Hb) content.
        • Normochromic: RBCs with a normal color, containing 33% Hb.
        • Hyperchromic: RBCs with an abnormally darker color due to excess Hb.

    Etiologic Anemia

    • Etiologic Anemia: Focuses on the causes behind the anemia, often related to problems with the production process of RBCs.

    Tonicity and Non-Penetrating Solutes

    • Non-penetrating solutes cannot cross the cell membrane.
    • Leaky ions, like chloride and sodium, are considered non-penetrating despite some movement across the membrane.
    • Osmolarity of body fluids is approximately 300 mOsm/L.
    • Na+/K+ ATPase pump maintains cell volume by pumping sodium out of the cell, counteracting osmotic pressure.
    • Tonicity refers to the effect a solution has on cell volume.
      • Hypotonic solution causes water to move into the cell, making it swell.
      • Isotonic solution has no effect on cell volume.
      • Hypertonic solution causes water to move out of the cell, making it shrink.
    • A hypotonic cell has lower osmolarity than its surroundings.
    • An isotonic cell in an isosmotic solution will not change volume as the osmotic pressures are balanced.
    • A hypertonic cell placed in a hypertonic solution will shrink due to the outward osmotic pressure.

    Hematopoiesis: Blood Cell Production

    • Hematopoietic stem cells give rise to all blood cells.
    • Erythropoiesis specifically refers to the formation of red blood cells.
    • Bone marrow cells are characterized by their ability to produce blood cells.
    • Megakaryocytes are the progenitor cells for platelets.
    • Lymphocytes are NOT a product of hematopoiesis.
    • Blood production in fetuses primarily occurs in the yolk sac, then the liver, and finally the spleen.
    • Children produce blood in the bone marrow and spleen.
    • Adults primarily produce blood in the bone marrow.
    • Order of blood production sites: Yolk sac -> Liver -> Spleen -> Bone marrow
    • Hematopoietic growth factors (HGFs) are cytokines that stimulate blood cell production.
    • HGFs primarily influence hematopoietic stem cells.
    • Cytokines such as HGFs are released by one cell and act on another cell to regulate cell function.
    • HGFs stimulate proliferation and differentiation of bone marrow stem cells.
    • Cytokines act as signals that trigger specific cellular responses.

    Red Blood Cells: Structure and Function

    • Hemoglobin is the primary gas transported by red blood cells, specifically oxygen.
    • Hemoglobin also helps regulate blood pH.
    • Mature red blood cells have a biconcave disc shape.
    • Low oxygen levels increase the number of red blood cells.
    • Spectrin is important for red blood cells as it provides structural integrity and flexibility.
    • A single red blood cell can carry a maximum of four oxygen molecules.
    • Increased pH increases hemoglobin's binding affinity for oxygen.
    • Hemoglobin carries approximately 20 mL of oxygen per 100 mL of blood with an average hemoglobin level of 15 g/100 mL.
    • Plasma's oxygen content is relatively low compared to oxygen bound to hemoglobin.
    • Hemoglobin molecular weight is approximately 64,500 Daltons.
    • Fully saturated hemoglobin can carry about 1.34 mL of oxygen per gram of hemoglobin.
    • Increased temperature decreases hemoglobin's oxygen-binding affinity (Bohr effect).
    • Men typically have 13-18 g of hemoglobin per 100 mL of blood.
    • Oxyhemoglobin contains approximately 98% bound oxygen.

    Erythropoiesis: Red Blood Cell Production Regulation

    • Erythropoietin (EPO) is released by the kidneys in response to low oxygen levels.
    • Glucocorticoids decrease the sensitivity of stem cells to EPO.
    • EPO stimulates erythropoiesis for approximately 5 days following its action on myeloid stem cells.
    • The negative feedback loop regulates erythropoiesis by controlling EPO levels.
    • Men generally have higher red blood cell counts than women due to higher testosterone levels.

    Red Blood Cell Maturation

    • Proerythroblasts are the precursors to reticulocytes.
    • Proerythroblasts decrease in size as they mature into reticulocytes.
    • Reticulocytes are characterized by the presence of residual ribosomes.
    • Reticulocytes synthesize hemoglobin during their development.
    • Reticulocyte formation takes about 1-2 days following initial stem cell differentiation.

    Red Blood Cell Recycling

    • Macrophages engulf and break down old or damaged red blood cells.
    • Iron is stored in the body as ferritin or hemosiderin after red blood cell breakdown.
    • Bilirubin levels above 1 mg/dL in blood plasma cause jaundice.
    • Hemolysis in newborns can lead to increased bilirubin levels.
    • Impaired bilirubin excretion can contribute to jaundice.

    Polycythemia

    • Absolute polycythemia is characterized by an increase in red blood cell count.
    • Secondary polycythemia can be caused by factors such as high altitude, smoking, or certain tumors.
    • Excess red blood cells in the bloodstream can lead to hyperviscosity and thrombosis.
    • Relative polycythemia is associated with dehydration.
    • Increased red blood cell production can be caused by factors like EPO, hypoxia, or genetic factors.

    Key Concepts Summary

    • Erythropoietin is the primary hormone regulating red blood cell production.
    • Macrophages break down old red blood cells, recycling iron.
    • Reticulocytes are immature red blood cells with residual ribosomes.
    • Low oxygen levels trigger EPO release.
    • Increased temperature reduces hemoglobin's oxygen-binding affinity.

    Anemia Classification

    • Morphological classification of anemia describes the appearance of red blood cells.
    • Hyperchromic red blood cells have an excess of hemoglobin.
    • Microcytic red blood cells are smaller than normal.
    • Normocytic red blood cells are normal in size.
    • Size of red blood cells determines whether an anemia is microcytic, normocytic, or macrocytic.

    Etiologic Anemia: Diminished Production

    • Aplastic Anemia: Anemia characterized by a lack of bone marrow production, resulting in normal-sized, normally colored red blood cells (normocytic, normochromic).
      • Unknown causes or exposure to radiation, chemicals, or drugs are common.
    • Stimulation Failure Anemia: Anemia caused by a deficiency in erythropoietin (EPO), a hormone produced by the kidneys that stimulates bone marrow production of red blood cells. This leads to a lack of EPO, resulting in normocytic, normochromic red blood cells.
      • Renal disease is a common underlying cause.

    Etiologic Anemia: Iron Deficiency Anemia

    • Iron Deficiency Anemia: Anemia caused by a lack of iron, leading to abnormally small and pale red blood cells (microcytic, hypochromic).
      • Can be caused by inadequate intake, increased demand, or blood loss (hemorrhage).
      • Different stages of life (infancy, adolescence, puberty, menstruation) have varying iron demands.
      • Human body contains approximately 4 grams of iron, with 65% found in hemoglobin, 30% stored, and 5% in myoglobin.
      • Dietary intake of iron averages 15mg/day with only 1mg/day absorption (2mg/day for menstruating individuals).
      • To maintain iron balance, the loss of 1mg/day iron from red blood cell destruction must be replaced, with 24mg recycled daily from 25mg/day needed for erythropoiesis.
      • Menstruation results in an estimated loss of 50ml blood/month, equivalent to 50mg iron. This necessitates a daily intake of 2mg iron to compensate.

    Ineffective Maturation

    • Vitamin B12 or folate deficiency impairs DNA synthesis and red blood cell (RBC) maturation.
    • Dietary lack of B12 (veganism) or folic acid/B9 (lack of fresh vegetables) can contribute.
    • Impaired absorption from the intestines due to lack of intrinsic factor in the ileum (pernicious anemia) also plays a role.
    • Characterized by macrocytic (large) and normochromic (normal color) RBCs.

    Increased RBC Destruction or Reduced Lifespan

    • Hemolytic anemia is characterized by increased destruction of RBCs, often accompanied by jaundice.
    • Can be congenital (genetic) or acquired (toxins, drugs, autoimmune disorders).
    • Underlying causes include abnormal RBC membrane structure (spherocytosis), metabolic abnormalities, abnormal hemoglobin structure (e.g., β-thalassemia), and more.

    Hemorrhage

    • External or internal bleeding may lead to hematomas, or accumulations of blood in tissues.
    • Hemostasis is the process of stopping bleeding following vascular injury.

    Primary Hemostasis

    • Begins within seconds of injury and lasts minutes.
    • Vascular Response:
      • Smooth muscle contraction causes vasoconstriction, decreasing blood vessel diameter and reducing blood loss.
      • Vasoconstriction can even lead to opposite sides of the vessel sticking together.
    • Platelet Response:
      • Platelets adhere to exposed collagen at the injury site, forming a white thrombus (platelet plug).
      • Platelets and endothelial cells release von Willebrand factor to facilitate platelet adhesion.
      • Platelets release cytokines:
        • Thromboxane A2 (TXA2) increases platelet stickiness.
        • ADP and serotonin act as vasoconstrictors, further reducing blood flow.
        • Platelet factor 3 (PF3) is released to promote coagulation and plug formation.
    • Net Result:
      • The release of these signaling molecules leads to aggregation and binding of more platelets at the injury site.
      • Ultimately, platelets consolidate and link together in fibrin, becoming structurally stable.

    Primary Hemostasis

    • Primary hemostasis is the initial response to vascular injury, occurring within seconds and lasting minutes.
    • Vascular Response: Vasoconstriction occurs, decreasing blood vessel diameter to minimize blood loss. This can even lead to the vessel's edges adhering.
    • Platelet Response:
      • Platelets adhere to exposed collagen at the injury site, forming a white thrombus (platelet plug).
      • Platelets and endothelial cells release von Willebrand factor, facilitating platelet adhesion to the injury site.
      • Platelets release cytokines, including:
        • Thromboxane A2 (TXA2): Increases platelet stickiness, enhancing aggregation.
        • ADP and serotonin: Act as vasoconstrictors, further reducing blood flow.
        • Platelet Factor 3 (PF3): Promotes coagulation and plug formation.
    • The cumulative effect of these actions is the aggregation and binding of more platelets at the injury site, solidifying the platelet plug.
    • Finally, platelets are consolidated by linking together with fibrin, resulting in a structurally stable plug.

    Secondary Hemostasis

    • Red thrombus formation signifies the activation of the coagulation pathway.
    • The coagulation pathway involves plasma proteins, clotting factors, and platelet-released proteins. These elements work together as enzymes and cofactors.
    • Calcium ions (Ca²⁺) and phospholipid agents contribute to the coagulation process.
    • The coagulation pathway leads to the formation of fibrin from fibrinogen.
    • Fibrin forms a cross-linked network, creating a stable blood clot.

    Secondary Hemostasis

    • A process that follows primary hemostasis
    • Involves coagulation pathway, which is a complex cascade of enzymatic reactions
    • Activated after platelet plug formation, which is a temporary fix
    • Requires clotting factors and calcium ions (Ca2+), phospholipids (PL), and platelets to be functioning properly
    • Creates a stable fibrin mesh, which strengthens the platelet plug, forming a red thrombus
    • Red blood cells (RBCs) are not essential for this process
    • The fibrin mesh is formed from fibrinogen, a soluble protein found in plasma, which is converted into insoluble fibrin by the coagulation cascade.

    Blood Coagulation Pathways

    • The extrinsic pathway, initiated by tissue factor, triggers prothrombinase activation within 15-20 seconds.
    • The intrinsic pathway, initiated by contact activation, takes 3-6 minutes to activate but is positively regulated by thrombin.
    • Both pathways converge on the common final pathway, involving prothrombinase activation.
    • Prothrombinase activation requires calcium ions (Ca²⁺) and phospholipids.
    • The intrinsic pathway utilizes additional cofactors like platelet factor 3 (PF3) and plasma factors.
    • The extrinsic pathway relies on plasma protein factors, which are a limited resource.
    • Endothelial cells release vasodilators, including nitric oxide (NO) and prostacyclin, to increase the flow of plasma proteins to the site of damage.

    Acquired Multi-Factor Deficiencies

    • Acquired multi-factor deficiencies involve simultaneous deficiencies in multiple clotting factors.
    • Causes of acquired multi-factor deficiencies include:
      • Acquired multi-fetide of encis Vackore ciehey ( unclear term, requires clarification)
      • Liver disease: Impaired synthesis and production of clotting factors.
      • Vitamin K deficiency: Essential cofactor for synthesis of clotting factors II (prothrombin), VII, IX, and X. Deficiency hinders their production.

    Clot Retraction

    • Platelets contain thrombosthenin, a contractile protein that shrinks clots.
    • Thrombosthenin forces fluid out of the clot, drawing injured tissues together.

    Clot Lysis

    • Clot formation is balanced by inhibitors of platelet adhesion and anticoagulants.
    • These inhibitors prevent the formation of large or excessive clots.

    Clot Inhibition Drugs

    • Aspirin inhibits platelet adhesion.
    • Coumarin blocks the synthesis of prothrombin, factors VII, IX and X.
    • Coumarin acts opposite to Vitamin K.
    • Heparin promotes the inhibition of thrombin activation and action.

    Clot Lysis Drugs

    • t-PA (tissue plasminogen activator) and streptokinase promote clot lysis.

    Clot Lysis

    • Clot lysis is the breakdown of a blood clot.
    • It is also known as fibrinolysis or thrombolysis.
    • Plasminogen in the plasma is converted to plasmin by plasminogen activators.
    • Plasmin is an enzyme that breaks down fibrin, the protein that forms the meshwork of a blood clot.
    • Plasminogen activators are substances that activate plasminogen.
    • These activators can be intrinsic or extrinsic.
      • Intrinsic proactivators are Factor XIIa (activated Hageman factor) or endothelial cell factors.
      • Extrinsic proactivators are tissue plasminogen activator (tPA) or streptokinase.
      • tPA is released from the endothelium of blood vessels.
      • Streptokinase is produced by certain bacteria.
      • Both tPA and streptokinase are used as medications to dissolve blood clots in patients with heart attacks, strokes, and pulmonary embolism.

    Petechiae

    • Small red or purple spots on the skin
    • Caused by bleeding into the skin
    • Can be a sign of uncontrolled bleeding

    Thrombocytopenia

    • Low platelet count
    • Thrombopoietin is a cytokine produced by the liver
    • Thrombopoietin stimulates platelet production

    Platelet Dysfunction

    • Platelets may be unable to function properly
    • Can be caused by deficiencies in clotting factors like:
      • Von Willebrand factor
      • Thromboxane A2 (TXA2)
      • Platelet factor 3 (PF3)

    Coagulation Disorders

    • Disorders that affect the blood clotting process
    • Can cause bleeding problems

    Loss of Vascular Integrity

    • Damage to blood vessels
    • Can cause bleeding

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    Explore the concept of tonicity and its role in osmosis in cell biology. This quiz covers how solutions affect cell membranes and the significance of non-penetrating solutes. Understand the typical osmolarity of body fluids and the transport mechanisms involved.

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