RBC abnormalities/Hemoglobin disorders Flashcards
Main function of RBC??
transport hemoglobin
What are the three classes of Anemia?
excessive blood loss
Excessive destruction
Deficient production
What are common causes of excessive blood loss?
2
Ulcers
GI bleeds
Large intestine= colon cancer-slow
esophageal varices = most rapid blood loss from the GI tract
What are common causes of excessive destruction of RBCs?
5
spleen(hemolytic anemias)-
sickle cell,
thalassemias,
autoimmune hemolytic anemia, membrane disorders,
What are the three common causes of deficient production of RBCS?
Deficiency in Iron
B12
Folate
What are the three types of morphologic classifications for anemia?
- Microcytic hypochromic (iron def- less heme-not as colorful)
- Normocytic normochromic- (anemia of chronic disease)
- Macrocytic normochromic (b12 and folate)
What are the three types of etiologic classifications for anemia?
Decreased production
Increased loss or destruction
Increased plasma volume (pregnancy)
Types of polycythemia?
3
- Primary polycythemia (Polycythemia vera-slow growing bone cancer that makes to many RBCs)
- Secondary polycythemia- altitude
- Benign erythrocytosis- regular amount of blood cells but decreased volume
Too many RBCs
Someone comes in with signs and symptoms of anemia (SOB and Fatigued). How do we diagnose it?
Why does this help with our diagnosis?
6
CBC w/ diff and smear
Tells us:
- number of RBCs
- amount of hemoglobin along
- size
- Smear looks at morphology
- First look at size, then kinetics (microcytic vs. macrocytic with MCV)
- Reticulocyte (precursor of mature RBCs) count….looks at destruction vs. production problem
- reticulocytes are normal or increases then its a destruction problem
What stage does hemoglobin synthesis start in RBC growth?
early erythroblast stage
-during its transformation from normoblast to reticulocyte
What color is a reticulocyte?
darker red
What color is a normal erythrocyte?
yellowish red
How long does it take for the stem cell to turn into a reticulocyte?
one week
Maturation of reticulocyte to erythrocyte takes how long?
How much of the body’s total red blood cells is generated each day?
24-48 hrs
1%
What is erythropoiesis governed by?
tissue oxygen needs
What is oxygen content sensed by and what does it do to regulate the changes?
Oxygen content is sensed by the kidneys, which produce the hormone erythropoietin
How does Erythropoietin act in the bone marrow?
by binding to receptors on committed stem cells
What are epo’s three functions?
3
- Promote hemoglobin synthesis, 2. increases membrane proteins, 3. causes differentiation of erythroblasts.
Why is hemoglobin’s binding of carbon dioxide a good thing and also a bad thing?
hemoglobin also binds carbon dioxide which is a problem because its similar to carbon monoxide which binds extremely tightly blocking O2.
important that it bonds CO2 so it can get it out of your system
When hemoglobin formation is defiecient what will happen to the cells?
2
iron deficiency for example.
1. percentage of hemoglobin in the cell may fall considerably and 2. the volume of the cell may decrease
When pressure of oxygen is high (as inthe pulmonary capillaries) what does hemoglobin bind?
When pressure of oxygen is low (as in the systemic tissue) what does hemoglobin bind?
oxygen and releases CO2
CO2 and releases Oxygen
What are all factors that affect hemoglobin function?
3
pH, Temp, and CO2 concentration
What are some conditions that favor the unloading of oxygen?
chronic lung disease/hypoxic pts- COPD
TEST QUESTION: Who binds to oxygen?
How many oxygen molcules does each hemoglobin carry?
iron, not heme
4
What is a hemoglobin chain made of?
What kind of chains does our hemoglobin have?
Heme + polypeptide
2 alpha chains + 2 beta chains => Hemoglobin A molecule
What kind of hemoglobin is found in fetuses?
Why do they have this?
When is this replaced?
hemoglobin F which is compased of 2 alpha and 2 gama chains
gamma instead of beta- has to have a higher affinity for oxygen-facilitates oxygen across the placenta
6 months replaced with hemoglobin A
Where is most of our iron at?
80%
Where is the other 20%?
Where does iron come from?
complexed to heme in hemoglobin
20% is stored in the bone marrow, liver, spleen, and other organs
get iron from diet (meat, fish, beans and legumes, iron), store it in your cells, body will recycle them
What is iron being transported through the blood called?
tranferrin
Transported in the plasma
What is iron being stored called?
Where is it stored?
ferritin
liver
Describe the breakdown and recycling of iron?
3
RBCs are destroyed in the spleen
iroin is released into circulation
and returns to bone marrow
for incorporation into new cells or stored in the liver
What happens to the cell as it ages?
Where does this occur?
becomes more and more fragile and can rupture in tight spots in circulation.
In the spleen because the spaces in the red pulp are very small (trabecular network)
What happens to the heme unit of the destroyed RBC?
bulk of heme is converted to bilirubin- removed from blood by liver to make it water soluable and excreted in the bile
How is the hemoglbin group transported to the right location after the RBC is destroyed?
macrophages of the spleen and bone marrow and kupffer cells of the liver.
These macrophages slowly release iron from the hemoglobin where it is carried by transferrin to the bone marrow or liver
What kind of bilirubin causes jaundice?
indirect, unconjugated and insoluable to plasma= jaundice
What is Hemolytic Anemia?
premature destruction of red cells
Two main types of hemoglobinopathies can cause red blood cell hemolysis. What are they?
- Abnormal substitution of an amino acid in the hemoglobin molecule, as in sickle cell anemia
- Defective synthesis of one of the polypeptide chains that form the globin portion of hemoglobin, as in the thalassemias
Genetic pathology of sickle cell disease?
Results from point mutation in Beta chain of hemoglobin molecule, with abnormal substitution of a single amino acid, valine, for glutamic acid.
How is sickle hemoglobin transmitted?
What are the two ways it can manifest?
recessive inheritance
Sickle cell trait (heterozygote with one HbS gene) or…
Sickle cell disease (homozygote with two HbS genes)