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Questions and Answers
Mature red blood cells (RBCs) are nucleated.
False
Total body water constitutes approximately 50% of body weight in a 70 kg male.
False
Erythropoietin is produced by the bone marrow.
False
The structure of red blood cells is spherical.
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The extracellular fluid (ECF) includes both interstitial fluid and plasma.
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Erythropoietin plays a role in the production of erythrocytes only in the presence of disease.
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Vitamin B12 and folic acid are essential for red blood cell production.
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Bone marrow is involved in RBC production only during childhood.
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The primary function of red blood cells is to transport carbon dioxide.
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Synthetic erythropoietin (EPO) can be used for blood doping in sports.
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The lifespan of red blood cells is approximately 90 days.
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Sickle Cell Disease is a genetic disorder that leads to the formation of fragile red blood cells.
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Foetal hemoglobin (HbF) binds oxygen more easily than adult hemoglobin (HbA).
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Total volume of blood in an adult human is typically around 6 liters.
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Anaemia can only result from a lack of iron in the diet.
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Bilirubin is a yellow pigment produced during the breakdown of heme from hemoglobin.
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Blood group O is classified as Rhesus positive and is considered the universal donor.
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The process of hemolysis involves the recycling of globin as amino acids.
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Haemoglobinopathies are conditions that involve normal hemoglobin only.
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Platelets play a significant role in the clotting process during haemostasis.
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Study Notes
Total Body Water
- Total body water comprises approximately 60% of body weight, around 40-45 liters in a 70 kg male.
- Divided into extracellular fluid (ECF) and intracellular fluid (ICF).
- ECF includes interstitial fluid (ISF) and plasma.
Composition of Blood > Plasma
- Plasma is a component of the extracellular fluid compartment.
Cellular Content of Blood
- Red blood cells
- White blood cells
- Platelets
Red Blood Cells
- Mature cells are non-nucleated.
- Biconcave shape, due to the lack of a nucleus, provides a large surface area for oxygen uptake and diffusion through the cell membrane.
RBC/Erythrocyte Production
- Begins in utero.
- Bone marrow takes over red blood cell production around 6-7 months.
- Children utilize all bone marrow for red blood cell production.
- In adults, only sternum, vertebrae, ribs, and pelvis are involved in red blood cell production.
- Requirements: Adequate nutrition including protein, vitamins (e.g., B12 and folic acid), and the hormone erythropoietin.
- Erythropoietin is released by the kidneys.
- Lack of RBC and/or Hb results in anemia, reducing the oxygen-carrying capacity of the blood.
Sequence of Events in RBC Production
- Proerythroblast: Large, nucleated cell with prominent nucleoli.
- Basophilic erythroblast: Smaller than proerythroblast, nucleus still prominent.
- Polychromatophilic erythroblast: Smaller than basophilic erythroblast, nucleus starting to condense.
- Orthochromatic erythroblast: Smaller than polychromatophilic erythroblast, nucleus is small and pyknotic.
- Reticulocyte: No nucleus, but still contains remnants of ribosomes.
- Mature red blood cell: Non-nucleated, biconcave disc-shaped.
Role of Erythropoietin in Production of Erythrocytes
- Increases red blood cell production to combat lack of oxygen in a physiological response to high altitude.
- Synthetic EPO is available for patients with chronic renal failure.
- EPO use in sports for blood doping is dangerous, leading to polycythemia, increased blood viscosity, and increased risk of heart failure and/or stroke.
Function of RBC
- Contain hemoglobin (Hb).
- Oxygen transport.
- Carbon dioxide transport.
- Blood buffer: Helps maintain the normal blood pH of 7.4.
Structure of Hemoglobin
- Four polypeptide chains: 2 α and 2 β in adult Hb A, 2 α and 2 γ in fetal Hb F.
- Fetal Hb (HbF) binds oxygen more easily than adult Hb (HbA), essential for oxygen uptake in utero. Transition to HbA occurs around 6 months of age.
- Each polypeptide is linked to one heme molecule.
- Each heme contains one iron atom to which oxygen associates.
- Hemoglobinopathies: Abnormal Hb, e.g., HbS in sickle cell disease, thalassemias.
Anemia > Many Causes
- Sickle cell disease: A genetic disorder that manifests in children as sickle cell hemolytic anemia. Sickled cells are fragile, leading to the need for blood transfusions. Cells become trapped in microcirculation, obstructing blood flow, causing ischemia, pain, stroke, jaundice, and respiratory symptoms.
Red Blood Cell Breakdown
- Lifespan of about 120 days.
- Cells become aged and fragile, trapping them in the spleen (the "red cell graveyard").
- Heme is separated from globin.
- Globin is recycled as amino acids.
- Heme breakdown yields iron, which is recycled.
- Other heme breakdown products yield biliverdin, which converts to bilirubin, a yellow pigment.
- Bilirubin is transported to the liver and excreted in bile.
- Jaundice: Occurs due to high levels of bilirubin in the blood. Can also occur in liver disease, where the diseased liver cannot handle even normal levels of bilirubin.
Blood Groups
- Blood group is determined by the antigen present on the red cell membrane.
- Each blood group is Rhesus+ or Rhesus-.
- Blood group O Rhesus- is the “Universal Donor,” as it lacks antigens to react with antibodies in the patient’s plasma.
Blood Transfusion
- Patients blood is typed, and then cross-matched with donor cells and patient’s serum.
- Antigen on donor cells must not react with corresponding antibody in patient’s plasma.
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Description
Explore the intricate details of total body water, blood plasma, and the cellular content of blood through this quiz. Understand the structure and function of red blood cells, including their production and nutritional requirements. Test your knowledge on these essential biological concepts.
