Hematology and Bilirubin Quiz

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Questions and Answers

What is the main reason bilirubin is bound to albumin?

To convert bilirubin into a soluble form

To prevent bilirubin from being absorbed by the liver

To increase the solubility of the whole molecule (correct)

To facilitate its rapid elimination from the body

What is the normal range of bilirubin levels in the blood?

16 – 100 μmol/l

1 – 2 mg/dl

0.1 – 1 mg/dl (correct)

1 – 16 μmol/l (correct)

What condition is indicated by a bilirubin level of 2 mg/dl?

Hemolytic anemia

Liver failure

Normal bilirubin levels

Jaundice (correct)

Which component is responsible for the production of erythrocytes?

Colony-forming unit—erythrocyte Signup and view all the answers

What is the function of reticulocytes in blood?

They are immature red blood cells Signup and view all the answers

Which type of cell is primarily involved in adaptive immunity?

B lymphocyte Signup and view all the answers

What key process is described by the ejection of the nucleus from a cell?

Erythropoiesis Signup and view all the answers

Which type of leukocyte is characterized as agranular?

Monocyte Signup and view all the answers

What condition is characterized by high globular lysis and harmful iron deposition in various organs?

Thalassemia major Signup and view all the answers

Which treatment helps in the prevention of harmful iron deposition in tissues?

Desferal Signup and view all the answers

What is a common consequence of untreated severe aplastic anemia?

Death Signup and view all the answers

Which factor is NOT associated with aplastic anemia due to bone marrow dysfunction?

Exposure to low-dose radiation Signup and view all the answers

How does severe anemia affect blood viscosity?

Causes it to fall significantly Signup and view all the answers

In which situation is bone marrow transplantation recommended?

Severe aplastic anemia Signup and view all the answers

Which of the following can lead to aplastic anemia?

High doses of insecticides Signup and view all the answers

What results from increased blood flow through tissues in cases of severe anemia?

Increased cardiac output Signup and view all the answers

What is the primary role of white blood cells (WBCs) in the body?

Defend the body against infections Signup and view all the answers

Which type of white blood cell is primarily responsible for phagocytosis?

Neutrophils Signup and view all the answers

What mechanism allows neutrophils and monocytes to reach the site of infection?

Diapedesis Signup and view all the answers

What is the main function of macrophages in the extravascular pathway for RBC destruction?

To phagocytize and lysate red blood cells Signup and view all the answers

What happens to amino acids released from the breakdown of globin during RBC destruction?

They are reused for protein synthesis Signup and view all the answers

What is the life span of granulocytes in blood?

4-8 hours Signup and view all the answers

Which type of WBC is known to be a more powerful phagocyte than neutrophils?

Monocytes Signup and view all the answers

What is the end product of heme breakdown that is excreted?

Bilirubin Signup and view all the answers

Where does erythropoiesis primarily take place after RBC death?

In red bone marrow Signup and view all the answers

What process involves the movement of WBCs toward the site of infection due to chemical signals?

Chemotaxis Signup and view all the answers

What is released into circulation for approximately 120 days?

Red blood cells Signup and view all the answers

Which white blood cell type constitutes approximately 60% of the circulation?

Neutrophils Signup and view all the answers

Which component binds and transports iron in the blood?

Transferrin Signup and view all the answers

Which of the following characteristics is true of basophils?

Release histamine Signup and view all the answers

What is the primary cause of jaundice in relation to RBC destruction?

Increased levels of bilirubin in the blood Signup and view all the answers

What is the fate of biliverdin in the RBC destruction process?

It is transformed into bilirubin Signup and view all the answers

What is the first step in blood hemostasis?

Vascular spasms Signup and view all the answers

Which factor is NOT required for the formation of a platelet plug?

Prothrombin Signup and view all the answers

Which substance is tested to determine kidney function related to RBC destruction?

Urobilinogen Signup and view all the answers

What role does ferritin play in relation to iron after RBC death?

Stores iron for future use Signup and view all the answers

What is the final product formed in the coagulation phase?

Insoluble fibrin Signup and view all the answers

Which of the following factors is involved in the initial vascular spasm?

Endothelin Signup and view all the answers

What is the origin of platelets?

Megakaryocyte Signup and view all the answers

Which substance is released by platelets during the formation of a platelet plug?

Thromboxane A2 Signup and view all the answers

What is the role of plasmin in the body?

Dissolves fibrin Signup and view all the answers

During which phase of coagulation is prothrombin converted to thrombin?

Phase 2 Signup and view all the answers

What is the role of calcium ions in the activation of factor XIII?

They stabilize and strengthen the clot by cross-linking fibrin. Signup and view all the answers

Which factors are synthesized in the liver and require Vitamin K for post translational modifications?

Factors II, VII, IX, X, protein C & protein S Signup and view all the answers

What is the structural basis of a clot?

Fibrin strands Signup and view all the answers

What distinguishes a soft clot from a hard clot?

The degree of fibrin cross-linking Signup and view all the answers

Which pathway begins with tissue factor (TF)?

Extrinsic pathway Signup and view all the answers

What is the primary function of fibrin during coagulation?

To trap red blood cells and platelets Signup and view all the answers

How does thrombin contribute to the formation of fibrin?

It induces the conversion of fibrinogen to fibrin. Signup and view all the answers

What does factor XIII do to fibrin?

It cross-links and stabilizes fibrin. Signup and view all the answers

Study Notes

Blood Physiology

Blood is a fluid connective tissue, vital for transporting oxygen from lungs to body parts and carbon dioxide from body parts to the lungs.
Blood volume in a healthy adult male is approximately 5 liters, and in a healthy adult female it is slightly less at 4.5 liters. It equates to about 8% of body weight in a 70kg healthy young adult.
Blood volume in a newborn baby is 450ml.
Blood increases during growth and reaches 5 litres by puberty.

Blood Composition

Blood has two primary components: plasma (55% of blood volume) and formed elements (45% of blood volume).
Formed elements include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
Plasma is primarily water (98%), with dissolved ions and plasma proteins (albumin, globulins, fibrinogen)
Hematocrit is a measure of the percentage of red blood cells in whole blood. Healthy males average 47% ± 5%, healthy females average 42% ± 5%.
Platelets = 250-400 thousand per cubic mm of blood
White blood cells = 5-9 thousand per cubic mm of blood
Red blood cells = 4.2-6.2 million per cubic mm of blood

Functions of Blood

Transport: Oxygen, carbon dioxide, nutrients, hormones, waste products
Homeostasis: Regulating body temperature and ECF pH
Protection: White blood cells and antibodies defend against infections
Clotting: Prevents blood loss through a complex cascade

Blood Cell Formation

Hematopoiesis is the process of blood cell formation
Erythropoiesis: Formation of red blood cells (RBCs) in yolk sac during early fetal stages. In the middle trimester, RBC formation moves to the liver and spleen. By the later stages of fetal development, and after birth, RBC formation is predominantly in the bone marrow.
Leucopoiesis: Formation of white blood cells.
Thrombopoiesis: Formation of platelets
Hematopoiesis: The process of producing all the materials of the blood

Production of Red Blood Cells (RBCs)

In Utero: Early weeks - yolk sac; Middle trimester - liver, spleen, and lymph nodes; Last months - bone marrow of all bones
After Birth: Bone marrow of flat bones continue to produce RBCs; Shaft of long bones stop RBC production at puberty, while epiphyses continue

Hematopoiesis

Yolk sac (3rd to 10th week)
Liver (6th to 32nd week)
Spleen (10th to 25th week)
Bone marrow (30th week to birth and also after birth)

Active Bone Marrow Locations

In adults, red bone marrow is primarily found in the axial skeleton, pelvic and pectoral girdles, and proximal epiphyses of the humerus and femur.

Normal Bone Marrow Conversion

Infants - all red bone marrow
Childhood (1-10 years) – red bone marrow remains in flat bones, shaft of long bones begin converting to yellow marrow
Adolescent (10-20 years) – red bone marrow in ribs, skull, vertebrae, hip bones
Adults – all areas of the skeleton convert to yellow marrow except flat bones

Bone Marrow

Red bone marrow (active)
Yellow bone marrow (inactive)

Regulation of RBC Production

Erythropoiesis is stimulated by erythopoietin, a hormone from the kidney, produced in response to hypoxia (low oxygen in the bloodstream) .
Hypoxia can be caused by low RBC count (anemia), hemorrhage, high altitude, or chronic heart/lung diseases.

Hemoglobin

A complex protein molecule, containing four globin protein chains, each bound to a heme group.
The heme group contains iron, which binds oxygen.
Normal types: Hb A, Hb A2, Hb F (fetal Hb)

Iron Metabolism

Iron is an essential component of hemoglobin and myoglobin.
65% of the body's iron is in hemoglobin; 4% in myoglobin and 1% in various heme compounds; 15-30% is stored as ferritin in the liver.

Erythropoiesis

RBC development is characterized by a decrease in cell size.
The nucleus disappears.
Hemoglobin (Hb) appears.

Maturation Factors

Vitamin B12, is essential for DNA synthesis, cell division and maturation of RBCs. Absorbed from small intestine in presence of an intrinsic factor from the stomach.
Folic acid is also essential for DNA synthesis. Deficiency can lead to Megaloblastic anemia.
Intrinsic factor is a protein produced in the stomach, necessary for the absorption of Vitamin B12

Erythrocyte Disorders

Polycythemia: Excess red blood cells (RBCs), above 7 million/cu mm in healthy adults.
- Primary Polycythemia (Polycythemia Vera): caused by red bone marrow malignancy. RBC count often above 14 millions/cu mm and WBC count is also increased.
- Secondary Polycythemia: Various causes including respiratory disorders (like emphysema, TB, pneumonia), congenital heart disease, and heart disease. Also can result from increased metabolism (e.g., hormonal imbalances). Higher levels of Erythropoietin can also result from severe conditions like high altitude or profound heart/lung disease.
Anemia: Deficiency of red blood cells, hemoglobin content or both.
- Blood Loss Anemia (e.g. hemorrhage)
- Due to malnutrition (iron, Vitamin B12, or protein deficiency)
- Abnormal hemoglobin (e.g., sickle cell anemia, thalassemia)
- Abnormal shape (e.g., hereditary spherocytosis)
- Aplastic anemia (bone marrow dysfunction), caused by high-dose radiation, chemotherapy, toxic chemicals, autoimmune disorders

Platelet Structure and Formation

Platelets originate from megakaryocytes in the bone marrow.
Platelets are cell fragments, with an irregular shape and lobed nuclei.
Platelets have a short lifespan (~8-12 days).
Platelets are crucial for hemostasis and blood clotting. Normal counts are 150,000–450,000 per cubic mm of blood.

Platelet Plug Formation

Exposed collagen triggers platelet adhesion and activation, releasing factors (ADP, thromboxane A2) that attract and aggregate more platelets to form a platelet plug.

Blood Coagulation

Series of reactions transforming blood from liquid to gel.
- Extrinsic Pathway: Activated by tissue trauma, involving Tissue factor, VIIa, and leads to thrombin formation.
- Intrinsic Pathway: Activated by blood contact with collagen, involving XII, XI, IX, VIII, and leads to thrombin formation.
- Common Pathway: These two pathways converge, and final steps involve conversion of Fibrinogen --> Fibrin, and formation of a clot

Anticoagulants

Chemicals that prevent blood clotting. Examples include EDTA, Oxalate, Heparin, Sodium Citrate, Sodium Fluoride/Potassium Oxalate
They oppose the procoagulant effect.

Other Factors Affecting Blood Clotting

Intact endothelial cells produce substances (prostacyclins and nitric oxide) to prevent platelet aggregation.
Damaged endothelial cells lose these and allow clotting.

Clot Retraction

Platelets contract, pulling the fibrin threads together, strengthening the clot.
Plasmin (from plasminogen) then degrades the fibrin, dissolving the clot after it no longer needed, allowing for wound healing.

Jaundice

Jaundice, or bilirubinemia, is characterized by a yellowing of skin and mucous membranes due to elevated bilirubin levels in the blood. Bilirubin is a breakdown product of old red blood cells. -Prehepatic jaundice: Excessive RBC breakdown -Intrahepatic jaundice: Dysfunction of liver cells (hepatocytes) -Posthepatic jaundice: Obstruction of bile duct

Normal Bilirubin Metabolism

Bilirubin metabolism involves unconjugated bilirubin being conjugated by the liver, and then excreted into bile, where it becomes urobilinogen and stercobilin, eliminated in the feces. A portion of urobilinogen will be reabsorbed into the bloodstream and processed by the kidneys.

Neonatal Jaundice

Common in premature infants, caused by transient bilirubin excess, potentially causing kernicterus brain damage. Phototherapy and exchange blood transfusions can be used to control bilirubin levels. A high bilirubin level within the first 24 hours of life is abnormal and requires additional testing to identify the cause.

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Description

Test your knowledge on hematology topics including bilirubin, erythrocytes, reticulocytes, and aplastic anemia. This quiz covers essential concepts related to blood components and their functions, normal ranges, and implications of various blood conditions. Perfect for students in health sciences or medical-related courses.