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Chapter 27: Disorders of Red Blood Cells Porth
Chapter 13: Disorders of Red Blood Cells Porth - Essentials of Pathophysiology 3rd edition
Terms in this set (60)
The ____ shape of an erythrocyte provides a larger surface area for oxygen diffusion than would a spherical cell of the same volume, and the thinness of the _____ enables oxygen to diffuse rapidly between the exterior and the innermost regions of the cell.
biconcave, cell membrane
The rate at which hemoglobin is synthesized depends on the availability of _____ for heme synthesis.
During its transformation from normoblast to reticulocyte, the RBC accumulates hemoglobin as the ____ condenses and is finally lost.
Mature red blood cells have a life span of approximately _____ months. (____ days).
The red blood cell relies on the _____ pathway for its metabolic needs.
Large doses of nitrites can result in high levels of ____, causing pseudocyanosis and tissue hypoxia.
The ____ measures the total number of red blood cells in a microliter of blood.
red blood cell count (RBC)
The ____ measures the volume of red cell mass in 100 mL of plasma volume.
The ____ is the concentration of hemoglobin in each cell.
mean corpuscular hemoglobin concentration (MCHC)
_____ is defined as an abnormally low number of circulating red blood cells or level of hemoglobin.
Tissue ____ can give rise to fatigue, weakness, dyspnea, and sometimes angina.
____ anemia is characterized by the premature destruction of red cells, the retention in the body of iron and the other products of hemoglobin destruction, and an increase in erythropoiesis.
Two main types of hemoglobinopathies can cause red cell hemolysis: the abnormal substitution of an amino acid in the hemoglobin molecule, as in ____ anemia, and the defective synthesis of one of the polypeptide chains that form the globin portion of hemoglobin, as in the _____.
sickle cell, thalassemias
Hereditary ____ is caused by abnormalities of the Spectrin and ankyrin membrane proteins that lead to a gradual loss of the membrane surface.
____ are caused by deficient synthesis of the β chain and ____ by deficient synthesis of the α chain.
The most common inherited enzyme defect that results in hemolytic anemia is a deficiency of _____.
_____ anemia results from dietary deficiency, loss of iron through bleeding, or increased demands
Iron deficiency in adults in the Western world is usually the result of _____.
chronic blood loss
_____ anemias are caused by impaired DNA synthesis that results in enlarged red cells as a results of impaired maturation and division.
_____ anemia is a specific form of megaloblastic anemia caused by atrophic gastritis.
____ describes a disorder of pluripotential bone marrow stem cells that results in a reduction of all three hematopoietic cell lines.
____ is an abnormally high total red blood cell mass with a hematocrit greater than 50%.
At birth, changes in the red blood cell indices reflect the transition to extrauterine life and the need to transport ____ from the lungs.
Jaundice in infants is the result of increased red cell breakdown and the inability of the immature liver to _____ bilirubin.
The diagnosis of _____ in the elderly requires a complete physical examination, a complete blood count, and studies to rule out comorbid conditions such as malignancy, gastrointestinal conditions that cause bleeding and pernicious anemia.
Caused by deficient globulin production
Severe G6PD deficiency
Chronic hemolytic anemia
Regulator of red blood cell production
Mean corpuscular volume
Measure of size of red blood cell
transports iron to plasma
conjugated with bilirubin to render it water
common cause of megaloblastic anemias
red blood cell production
yellow discoloration of skin due to high levels of bilirubin
normal hemoglobin concentration in red blood cell
Hemoglobin is the oxygen-carrying protein found in red blood cells. Describe the molecular structure of hemoglobin. Also, explain how oxygen interacts with hemoglobin.
The hemoglobin molecule is composed of two pairs of structurally different alpha and beta polypeptide chains. Each of the four-polypeptide chains consists of a globin (protein) portion and heme unit, which surround an atom of iron that binds oxygen. Thus, each molecule of hemoglobin can carry four molecules of oxygen. The binding that occurs is cooperative, or allosteric. When one oxygen molecule binds, it makes it easier for the next to bind. The process also works in reverse.
Red blood cells have a finite life span. How long is the life span, and what is the fate of red blood cells?
A group of large phagocytic cells found in the spleen, liver, bone marrow, and lymph nodes facilitates the destruction of red blood cells. These phagocytic cells recognize old and defective red cells and then ingest and destroy them in a series of enzymatic reactions. During these reactions, the amino acids from the globulin chains and iron from the heme units are salvaged and reused. The bulk of the heme unit is converted to bilirubin, which insoluble in plasma and attaches to plasma proteins for transport. Bilirubin is removed from the blood by the liver and conjugated with glucuronide to render it water-soluble so that it can be excreted in the bile.
What are three categories of anemic effects?
1. Manifestations of impaired oxygen transport and the resulting compensatory mechanisms.
2. Reduction in red cell indices and hemoglobin levels.
3. Signs and symptoms associated with the pathologic process that is causing the anemia.
Describe and explain the two consequences of sickle cell anemia.
Premature destruction of the cells due to the rigid nondeformable membrane occurs in the spleen, causing hemolysis and anemia due to a decrease in red cell numbers. Secondly, vessel occlusion, a complex process involving an interaction among the sickled cells, endothelial cells, leukoctes, platelets, and other plasma proteins will interrupt blood flow. The adherence of sickled cells to the vessel endothelium causes endothelial activation with liberation of inflammatory mediators and substances that increase platelet activation and promote blood coagulation.
Anemia is a common side effect of cancer treatments. Which type of anemia usually develops and why?
Exposure to high doses of radiation, chemicals, toxins that suppress cellular activity directly or through immune mechanisms are the standard cancer treatments. Chemotherapy and irradiation commonly result in bone marrow depression, which causes anemia, thrombocytopenia, and neutropenia. Identified toxic agents include benzene, the antibiotic chloramphenicol, and the alkylating agents and antimetabolites used in the treatment of cancer will decrease bone marrow of stem cells, thus affecting the production of red blood cells.
Polycythemia vera is a neoplastic disorder of red blood cells. Describe the complication that arise from the rapid increase in hematocrit.
Viscosity rises exponentially with the hematocrit and interferes with cardiac output and blood flow. Hypertension is common and there may be complaints of headache, dizziness, inability to concentrate, and some difficulty with hearing and vision because of decreased cerebral blood flow. Venous stasis gives rise to a plethoric appearance or dusky redness, even cyanosis, particularly of the lips, fingernails, and mucous membranes. Because of the increased concentration of blood cells, the person may experience itching and pain in the fingers or toes, and the hypermetabolism may induce night sweats and weight loss.
Infantile jaundice is caused by the underdeveloped liver being unable conjugate bilirubin. What are the treatment methods for infantile jaundice and how do they work?
Hyperbilirubinemia in the neonate is treated with phototherapy or exchange transfusion. Phototherapy is more commonly used to treated jaundiced infants and reduce the risk of kernicterus. Exposure to fluorescent light in the blue range of the visible spectrum (420 - to 470- nm wavelength) reduces bilirubin levels. Bilirubin in the skin absorbs the light energy and is converted to a structural isomer and is more water-soluble and can be excreted in the stool and urine.
All cells of the body age and are replaced in a natural order. When red blood cells age, they are destroyed in the spleen. During this process the iron from their hemoglobin is released into the circulation and returned where?
To the bone marrow for incorporation into new red blood cells. When red blood cells age and are destroyed in the spleen, the iron from their hemoglobin is released into the circulation and returned to the bone marrow for incorporation into new red blood cells or to the liver and other tissues for storage. Iron is not bound to red blood cells in the liver. Iron does not bind with oxygen in the lung without first being incorporated into a red blood cell. Iron is stored in tissues of the body, but not for strength, only for its oxygen-binding capacity.
Bilirubin is the pigment of bile and is made when red blood cells die. There are two types of bilirubin that can be measured in the blood and reported on by the laboratory. What does the laboratory report them as?
Direct and indirect. The plasma-insoluble form of bilirubin is referred to as unconjugated bilirubin and the water-soluble form as conjugated bilirubin. Serum levels of conjugated and unconjugated bilirubin can be measured in the laboratory and are reported as direct, indirect, respectively.
Neonatal hyperbilirubinemia is an increased level of bilirubin in the infant's blood. It is usually a benign condition characterized by what?
A yellow, jaundiced color. Hyperbilirubinemia, an increased level of serum bilirubin is a common cause of jaundice in the neonate. A benign, self-limited condition, it most often is related to the developmental state of the neonate. Rarely, cases of hyperbilirubinemia are pathologic and may lead to kernicterus and serious brain damage.
Anemia resulting from blood loss can be reversed if the blood loss is not so severe that it results in death. How long does it take for the red cell concentration to return to normal?
3 to 4 weeks. It takes about 5 days for the progeny of stem cells to fully differentiate, an event marked by increased reticulocytes in the blood. If the bleeding is controlled and sufficient, iron stores are available. The red cell concentration returns to normal within 3 to 4 weeks.
During chronic blood loss, iron-deficiency anemia occurs. Most patients are asymptomatic until their hemoglobin falls below 8 g/dL. The red cells that the body does produce have too little hemoglobin. What is the term for the resulting anemia?
Microcytic hypochromic. Chronic blood loss does not affect blood volume, but instead leads to iron-deficiency anemia when iron stores are depleted. It is commonly caused by gastrointestinal bleeding and menstrual disorders. Because of compensatory mechanisms, patients are commonly asymptomatic until the hemoglobin level is less than 8 g/dL. The red cells that are produced have too little hemoglobin, giving rise to microcytic hypochromic anemia. Macrocytic anemia is when the red blood cells are larger than normal. Hyperchromic means the cells are a darker color red than they should be.
In hemolytic anemia the red blood cells are destroyed prematurely. What distinguishes almost all types of hemolytic anemia?
Normocytic normochromic cells. Hemolytic anemia is characterized by the premature destruction of red cells, the retention in the body of iron and the other products of hemoglobin destruction, and an increase in erythropoiesis. Almost all types of hemolytic anemia are distinguished by normocytic and normochromic red cells.
When hemolytic anemia has intravascular hemolysis, it can be characterized in different ways. What is not a characterization of hemolytic anemia with intravascular hemolysis?
Spherocytosis. In hemolytic anemia, intravascular hemolysis is less common than extravascular hemolysis and occurs as a result of complement fixation in transfusion reactions, mechanical injury, or toxic factors. It is characterized by Hemoglobinemia, Hemoglobinuria, jaundice, and hemosiderinuria. Spherocytosis is the most common inherited disorder of the red cell membrane and is not associated with hemolytic anemia.
Aplastic anemia is a serious anemia that is a disorder of the pluripotential bone marrow stem cells and causes all three hematopoietic cell lines to be reduced. What is the treatment for aplastic anemia in the young and severely affected client?
Bone marrow transplant. Therapy for aplastic anemia in the young and severely affected includes stem cell replacement by bone marrow or peripheral blood transplantation Histocompatible donors supply the stem cells to replace the patient's destroyed marrow cells. A liver transplant will not produce new blood cells for the body. Spleen transplants are not done and would not produce new blood cells for the body.
When a client is in chronic renal failure, he or she almost always has anemia because of a deficiency to the anemia experienced by clients in chronic renal failure?
Uremic toxins and retained nitrogen. Chronic renal failure almost always results in anemia, primarily because of a deficiency of erythropoietin. Unidentified uremia toxins and retained nitrogen also interfere with the actions of erythropoietin, and red cell production and survival. Hemolysis and blood loss associated with hemodialysis and bleeding tendencies also contribute to the anemia of renal failure. Fibrinogen is essential for blood clotting, not oxygen transportation.
When an Rh-negative mother gives birth to an Rh-positive infant, the mother usually produces antibodies that will attack any subsequent pregnancies in which the fetus is Rh-positive. When subsequent babies are Rh-positive, erythroblastosis fetalis occurs. What is another name for erythroblastosis fetalis?
Hemolytic disease of the newborn. Erythroblastosis fetalis, or hemolytic disease of the newborn, occurs in Rh-positive infants of Rh-negative mothers who have been sensitized. The Rh-negative mother usually becomes sensitized during the first few days after delivery, when fetal Rh-positive red cells from the placental site are released into the maternal circulation. Because the antibodies take several weeks to develop, the first Rh-positive infant of an Rh-negative mother usually is not affected. There is no such thing as microcytic or macrocytic disease of the newborn, nor is there a hemolytic iron-deficiency anemia.
Pernicious anemia is thought to be an autoimmune disease that destroys the gastric mucosa. This results in chronic atrophic gastritis and the production of antibodies that interfere with ____ binding to intrinsic factor.
Pernicious anemia is thought to be an autoimmune disease that destroys the gastric mucosa. This results in chronic atrophic gastritis and the production of antibodies that interfere with vitamin B12 binding to intrinsic factor. Pernicious anemia is believed to result from immunologically mediated, possibly autoimmune, destruction of the gastric mucosa. The resultant chronic atrophic gastritis is marked by loss of parietal cells and production of antibodies that interfere with binding of vitamin B12 to intrinsic factor.
Sickle cell anemia is an inherited disorder seen in African American people. It is marked by the characteristic sickling of red blood cells. This causes both chronic hemolytic anemia and occlusion of blood vessels. Which are considered to be triggers of an episode of sickling?
Infection, stress, and dehydration. Factors associated with sickling and vessel occlusion include cold, tress, physical exertion, infection, and illness that cause hypoxia, dehydration, or acidosis.
Mean corpuscular hemoglobin concentration (MCHC)
The volume or size of the red cells
Mean cell hemoglobin (MCH)
The concentration of hemoglobin in each cell
Mean corpuscular volume (MCV)
The mass of the red cell
A pregnant woman at her first prenatal visit complains to the nurse that she is always tired. The nurse knows that fatigue is one symptom of anemia. What are other symptoms of anemia?
Faintness and dim vision. In anemia, the oxygen-carrying capacity of hemoglobin is reduced, causing tissue hypoxia. Tissue hypoxia can give rise to fatigue, weakness, dyspnea, and sometimes angina. Hypoxia of brain tissue results in headache, faintness, and dim vision. The redistribution of the blood from cutaneous tissues or a lack of hemoglobin causes pallor of the skin, mucous membranes, conjunctiva, and nail beds. Tachycardia and palpitations may occur as the body tries to compensate with an increase in cardiac output. Ruddy skin and bradycardia are not signs or symptoms of anemia.
Polycythemia vera most often occurs in men with a median age of 62. It is a neoplastic disease of the bone marrow that is characterized by what signs and symptoms?
Headache, dusky red appearance, and hearing difficulty. Primary polycythemia, or polycythemia vera, is a neoplastic disease of the pluripotent cells of the bone marrow characterized by an absolute increase in total red blood cell mass accompanied by elevated white cell and platelet counts. It most commonly is seen in men with a median age of 62 years, but may occur at any age. In addition, early findings include splenomegaly and depletion of iron stores. Hypertension is common and there may be complaints of headache, dizziness, inability to concentrate, and difficulty with hearing and vision because of decreased cerebral blood flow. Venous stasis gives rise to a plethoric appearance or dusky redness, even cyanosis, particularly of the lips, fingernails, and mucous membranes.
Thalassemia can be classed as major or minor. In thalassemia major it is necessary to start ___ therapy as early as 6 months of age. If therapy is not started in infants who present with this disease, severe growth retardation will occur.
Thalassemia can be classed as major or minor. In thalassemia major it is necessary to start transfusion therapy as early as 6 months of age. If therapy is not started in infants who present with this disease, severe growth retardation will occur. Persons who are homozygous for the trait (thalassemia major) have severe, transfusion-dependent anemia that is evident at 6 to 9 months of age when the hemoglobin switches from HbF to HbA. If transfusion therapy is not started early in life, severe growth retardation occurs in children with the disorder.
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