Unit 2 - Blood Disorders (Midterm #1) Flashcards
What is the disorder called when there is an excess of RBCs?
Polycythemia
What is the disorder called when there is a reduction in hemoglobin (Hb)?
Anemia
What is primary polycythemia due to?
Due to cancer of erythropoietic cells in the red bone marrow
If a patient has primary polycythemia, how high could you expect their hemoglobin to be?
80%
- RBC count as high as 11 million (instead of 4-6 million)
What is secondary polycythemia due to?
Dehydration, emphysema, high altitude, or physical conditioning
Why is polycythemia experienced if the patient exercises a lot?
The more we exercise, the higher the oxygen consumption, the more RBCs are produced to transport the needed oxygen
What are the dangers of polycythemia?
- Increased blood volume, pressure and viscosity
- Could result in embolism, stroke, or heart failure
What are some clinical manifestations of polycythemia
- Hypertension
- Dark red or flushed face
- Headaches, visual problems, neurologic symptoms
- Splenomegaly
- Hypercellular bone marrow
If a patient has polycythemia, why would they experience headaches, visual problems, or neurological symptoms?
There would be an increase in intracranial pressure
- there could be hypo-perfusion
- clotting is possible
If a patient has polycythemia, why would they experience splenomegaly? What is it?
An enlarged spleen
- spleen is overworked, breaking down old RBCs causing it to increase in size
At what levels is a patient defined as being anemic?
What are the three things that are associated with anemia?
- Presence of abnormal hemoglobin
- Reduced number of RBCs (low hemoglobin, low iron -> low oxygen)
- Structural abnormalities of RBCs (don’t have structure that accommodates oxygen binding)
What are the key causes of anemia?
- Inadequate vitamin B12 - critical for the synthesis of heme
- Inadequate folic acid - needed for synthesis of heme
- Iron deficiency
- Kidney failure (not enough EPO)
- Blood loss
- RBC destruction
What are the effects of anemia?
- tissue hypoxia and necrosis
- low blood osmolarity (tissue edema)
- low blood viscosity (heart races and pressure drops)
What happens if we have low blood osmolarity?
If we do not have enough heme in the blood vessel, the water will NOT be drawn into the blood vessel, results in edema in the tissues
What are three etiological classifications of anemia?
- Decreased hematopoiesis
- Abnormal hematopoiesis
- Increased loss and destruction of RBCs
What does hematopoiesis mean?
To make new RBCs
What are the three causes for decreased hematopoiesis (anemia)?
- Bone marrow failure
- Deficiencies of nutrients
- Chronic diseases
What are the two kinds of bone marrow failure in decreased hematopoiesis?
- Aplastic anemia (deficient in all types of blood cells)
2. Myelophthisic anemia (RBCs retain nuclues, not good for O2 transport)
What are the different types of nutrient deficiencies that cause decreased hematopoiesis?
- Vitamin B12 and folic acid
- Protein deficiency
- Iron deficiency
What is megaloblastic anemia?
Deficient in vitamin B12 and folic acid (decreased hematopoiesis)
- immature RBCs that are released into circulation
Why is decreased hematopoiesis caused by a protein or iron deficiency?
Globin is a protein (part of hemoglobin) and iron are essential for the transport of O2
What are the causes for decreased Fe+2 in the body?
- Increased loss of iron (chronic bleeding)
- Inadequate iron intake or absorption
- Increased iron requirements
What happens to iron in the stomach?
Converted from Fe+3 to Fe+2.
- excessive sue of antacids can lead to inadequate iron absorption (decreasing pH of the stomach so that the conversion cannot occur)
What are the two kinds of abnormal hematopoiesis?
- Sickle cell anemia
2. Thalassemia
What is hemolytic anemia?
Increased loss and destruction of RBCs (associated with bleeding, intrasplenic sequestration, immune hemolysis, and infections)
What in intrasplenic sequestration?
When the spleen store RBCs
What is hemolytic anemia?
- increased RBC destruction (intracellular or extracellular)
What is immune hemolytic anemias?
Mediated by antibodies that destroy RBCs
- mismatched blood transfusions
- hemolytic disease of newborn
What does to following mean?
- Normocytic
- Normochromic
- Microcytic
- hypochromic
- macrocytic
- Normocytic = normal size
- Normochromic = normal colour
- Microcytic = smaller cells
- hypochromic = paler cells
- macrocytic = larger cells
Describe sickle-cell disease.
Hereditary Hb defect (HbS instead of HbA)
- caused by recessive allele, which modifies hemoglobin structure
How does “sickling” occur in Sickle-cell disease?
- beta chains link together when hemoglobin is deoxygenated
- Forms long chains
- Chains cause cells to sickle
Why do sickle-cells clump together?
Sickle cells “poke” each other causing clumpting (aggluntination) that block small blood vessels
Why is the cranium and the spleen enlarged for sickle-cell disease?
Cranium = constantly producing new RBCs, b/c of hypoxic conditions
Spleen is enlarged b/c it is working to destroy damaged RBCs
What protection does sickle-cell disease provide?
Protection against malaria
- parasites cannot digest HbS (cannot digest abnormal hemoglobin)
What is thalassemia?
Genetic defect in the synthesis of HbA that reduces the rate of globin chain synthesis
What is the difference between thalassemia minor and major?
Minor = only 1 parent had the gene Major = both parents have the gene
What are clinical manifestations of thalassemia?
- hypochromic anemia (paler RBCs)
- splenomeglay (enlarged spleen b/c RBCs are dying easily)
- Hemosiderosis = accumulation of iron in tissues
- Hepatomegaly = enlarged liver b/c of iron storage
What is ferritin?
Chief iron storage protein in tissues
- If there is a high level of Fe+2 in the blood, there will also be a high level of ferritin, b/c ferritin is needed to transport all that Fe+2
What three things result in bleeding disorders?
- Vessel wall related
- Platelet related
- Clotting factor related
What is the normal platelet count range?
130,000 - 400,000 platelets per microlitre
What is the function of platelets?
- Secrete clotting factors
- Form temporary platelet plugs
What is hemostasis?
Stopping the flow of blood
What are the two pathways through which normal hemostasis occurs?
- Extrinsic pathway
2. Intrinsic pathway
What factor is part of the common pathway?
Factor X (ten)
Describe the steps involved in the common pathway.
Factor X –> Prothrombinase - converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin. Fibrin creates strands that plug
Why can leukemia cause a platelet disorder?
There is a demand for leukocytes, the red bone marrows won’t have space to create megloblastocytes (creates platelets)
What does DIC stand for?
Disseminated intravascular coagulation
What happens during DIC?
Infection, tumors, or shock create many small clots in the blood vessels. Prone to thrombi! Increased risk of bleeding b/c all the platelets are being used up in the small clots
