Chapter 23

Question 1

Red blood cell development

Answer 1

. Erythroblasts are continuously being formed from the pluripotent stem cells in the bone marrow

• They move through a series of divisions to develop into mature red blood cells.
• Normoblast to reticulocyte, the red blood cells accumulates hemoglobin as the nucleus condensed and is lost.
• The red cell loses its mitochondria and ribosomes.

Question 2

Function of the red blood # 1

Answer 2

. Transportation of oxygen to the tissues
- Hemoglobin binds some carbon dioxide and carried it from the tissues to the lungs
- The hemoglobin molecule is composed of two pairs of structurally different polypeptide chains.
. Each of the four polypeptide chains consist of a globin (protein) portion and heme unit, which surrounds an atom of iron that binds oxygen

Question 3

Function of red blood # 2

Answer 3

• Each molecule of hemoglobin can carry four molecules of oxygen
  . The production of each type of globin chain is controlled by individual structural genes with five different gene loci
  -Mutations can occur anywhere in these five loci

Question 4

Erythropoiesis

Answer 4

. Red cells are produced in the red bone marrow after birth
. Until 5 years of age, almost all bones produce red cells to meet growth needs; after 5 years, bone marrow activity gradually declines.
. After 20 years, red cell production takes place mainly in the membranous bones of the vertebrae, sternum, ribs and pelvis.
. With this reduction in activity, the red bone marrow is replaced with fatty yellow bone marrow.

Question 5

Hemoglobin Structure

Answer 5

. Globin
-a
-B beta
. Heme
-Iron
-porphyrin 
. Oxygen binding

Question 6

Red Blood Cell destruction

Answer 6

. The red blood cell has a life span of approximately 120 days
- It is broken down in the spleen
- The degradation products (iron and amino acids) are recycled.
. The heme molecule is converted to bilirubin and transported to the liver.
- it is removed and rendered water soluble for elimination in the bile.

Question 7

Bilirubin

Answer 7

. The heme unit is converted to bilirubin
. Bilirubin is insoluble in plasma and attached to plasma proteins for transport
- unconjugated
. Removed from the blood by the liver and conjugated with glucuronide to render it water soluble
- conjugated
. Jaundice

Question 8

Laboratory Tests for Red Blood Cells # 1

Answer 8

. Red blood Cell count ( RBC)
-Measures the total number of red blood cells in 1 mm 3 of blood
. Percentage of reticulocytes ( normally approximately 1%)
-Provide an index of the rate of red cell production

Question 9

Laboratory Test for Red Blood Cells # 2

Answer 9

. Hemoglobin ( grams per 100 mL of blood)
- Measures the hemoglobin content of the blood
. Hematocrit
- Measures the volume of red cell mass in 100 mL of plasma volume

Question 10

Transfusion Therapy

Answer 10

. Provides the means for replacement of red blood cells and other blood components
. Four major ABO blood types are determined by the presence or absence of two red cells antigens : A and B
- The presence of D antigen determines the Rh- positive type
- The absence of the D antigen determines the eh negative type

Question 11

Red blood cell components used in transfusion therapy

Answer 11

. Whole blood 
.Red blood cells
. Leukocytes reduced blood cells
. Washed red blood cells
 . Frozen red blood cells

Question 12

Signs and symptoms of transfusion Reactiond

Answer 12

. Sensation of heat along the vein where the blood is being infused
. Flushing of the face
. Urticaria, headache, pain in the lumbar area
. Chills, fever, constricting pain in the chest
. Cramping pain in the abdomen
. Nausea, vomiting
. Tachycardia, hypotension, and dyspnea

Question 13

Anemia

Answer 13

. Definition
- An abnormally, low number of circulating red blood cells or level of hemoglobin, or both
- Results is diminished oxygen- carrying capacity
. Causes
- Excessive loss or destruction of red blood cells
- Deficient red blood cell production because of a lack of nutritional elements or bone marrow failure

Question 14

Manifestations of Anemia

Answer 14

. Impaired oxygen transport with resulting compensatory mechanisms
. Reduction in red cell indices and hemoglobin levels
. Signs and symptoms associated with the pathological process that is causing the anemia

Question 15

Anemias of deficient red cell production

Answer 15

. Iron deficiency anemia
. Megaloblastic anemia
- Cobalamin deficiency anemia
- Folic acid deficiency anemia
. Aplastic anemia
. Chronic disease anemia

Question 16

G6PD

Answer 16

. A hereditary deficiency of glucose -6 phosphate dehydrogenase predispose to oxidative denaturation of hemoglobin, with resultant red cell injury and lysis

Question 17

Intravascular and extracvascular hemolysis

Answer 17

. Extra vascular hemolysis occurs when red blood cells become less deformable, making it difficult for them to transverse the splenic sinusoids

. Intravascular hemolysis occurs as a results of complement fixation in transfusion reactions, mechanical injury, or toxic factors.

Question 18

Sickle Cell Disease and Thalassemias

Answer 18

. Sickle cell disease is an inherited disorder in which an abnormal hemoglobin leads to chronic hemolytic anemia, pain, and organ failure
. The thalassemias are a group of inherited disorders of hemoglobin synthesis leading to decreased synthesis of either the a- or b globin chains of HbA

Question 19

Cause of sickling in sickle cell disease

Answer 19

. The abnormal structure of Hbs results from a point mutation in the b chain of the hemoglobin molecule, with an abnormal substitution of a single amino acid, valine, for glutamic acid

Question 20

Iron deficiency Anemia

Answer 20

. Iron deficiency is a common worldwide cause of anemia affecting people of all ages. The anemia results from dietary deficiency, loss of iron through bleeding, or increased demands.
. Because iron is a component of heme, a deficiency leads to decreased hemoglobin synthesis and consequent impairment of oxygen delivery.

Question 21

Vitamin B12 Deficiency

Answer 21

. The hallmark of vitamin B12 deficiency is megaloblastic anemia
. When vitamin B12 is deficient, the red cells that are produced are abnormally large because of excess cytoplasmic growth and structural proteins.

Question 22

Causes of Aplastic Anemia

Answer 22

. Among the causes of aplastic anemia are exposure to high doses of radiation, chemicals, and toxins that suppress hematopoiesis directly or through immune mechanisms

Question 23

Polycythemia # 1

Answer 23

. Definition
- A condition in which the red blood cell mass is increased

. Types
- Relative polycythemia: : results from a loss of vascular fluid and is corrected by replacing the fluid

Question 24

Polycythemia # 2

Answer 24

• Primary polycythemia: a proliferative disease of the bone marrow with an absolute increase in total red blood cell mass accompanied by elevated white cell and platelet counts
• Secondary polycythemia: results from increased erythropoietin levels caused by hypoxia conditions such as chronic heart and lung disease

Question 25

Polycythemia Manifestations

Answer 25

. Variable and related to an increase in RBC’s , hemoglobin level, and hematocrit with increased blood volume and viscosity

• Splenomegaly
• Depletion of iron
• Disrupted cardiac output
• hypertension
• Decreased cerebral blood flow
• Venous stasis
• Thromboembolism and hemorrhage

Question 26

Neonatal Blood

Answer 26

. Hemoglobin Concerntrations at birth are high, reflecting the high synthetic activity in utero to provide adequate oxygen delivery.
- HbF versus HbA
. Affinity of F versus A
. Hyperbulirubinemia
- unconjugated versus conjugated 
- Phototherapy 
. Hemolytic disease

Question 27

Aging and Red Blood Cells # 1

Answer 27

. Age - associated decline in the hematopoietic reserve

• Reduction in hematopoietic progenitors
• Reduced production of hemotopoietic growth factors
• Inhibition of erythropoietin
• Inflammatory cytokines interfere with erythropoietin interaction with its receptors.

Question 28

Aging and Red Blood cells# 2

Answer 28

. Anemia
- Hb decreases with age
- RBC production decreases with age
- Complete blood count
. Peripheral blood smear and a reticulocyte count and index
- Studies to rule out comorbid conditions such as malignancy, gastrointestinal conditions that cause bleeding , pernicious anemia