Erythrocyte Physiology Flashcards
How is hematocrit level determined?
Height of RBCs/Total height of sample in tube
What are the 3 primary functions of erythrocytes?
Carry O2 from lungs to body
Carry CO2 from body to lungs
Acid/base buffering
What aspects of erythrocytes contribute to increased surface area for efficient gas exchange?
Biconcavity
Erythropoiesis occurs on erythroblastic islands of ______ ________.
__________ mature into erythrocytes upon entering circulation
Bone marrow
Reticulocytes
At what point in erythropoeisis does EPO become necessary to continue the maturation process?
CFU-E (EPO bidns to EPOR on the cell)
At what stage of erythropoiesis does enucleation occur?
Between orthoerythroblast and reticulocyte
At what stage of erythropoiesis does degradation of residual organelles and microvesicle exocytosis occur?
Between reticulocyte and mature RBC
___________ is the principle regulator of erythropoiesis
Erythropoieitin
A genetic deletion in Hypoxia Inducible Factor may result in what condition?
Anemia
Impaired regulation of HIF would result in what pathologic condition?
Erythrocytosis
Mutations in HIF may lead to what pathologic condition?
Polycythemia
What happens to EPO-producing renal cells under hypoxic conditions?
Increases
What 3 conditions stimulate EPO production to increase in the kidneys?
Anemia
Decreased renal blood flow
Central hypoxia
What 2 factors are necessary in order to get from a normoblast to a reticuocyte?
B12 and folate
Why is it beneficial that tissue oxygenation operates on a negative feedback mech. in response to hypoxia?
Prevents increase in blood viscosity
True or false: folate is the same as folic acid
False
Requirements for erythropoiesis include:
Adequate _______
_______ availability
Vitamin ____ and Vitamin ______ for DNA synthesis
Nutrition; iron; B12; B9
__________ or _________ Deficiency results in megaloblastic macrocytic anemia
Folate; B12
Poor B12 absorption due to an autoimmune disorder results in ___________ anemia
Pernicious
What type of anemia is iron-deficient?
Microcytic anemia - most common cause of anemia worldwide
Iron circulates in plasma as _____________
Transferrin
___________ anemia results from deficient transport of transferrin to developing erythroblasts
Hypochromic
Iron absorption is enhanced by ___________
Ascorbate (vit. C)
What compounds impair iron absorption?
Hepcidin
Phytates
Tannins
ANTACIDS
Iron overload
Hemochromatosis
What are the 3 types of hemochromatosis
Primary (genetic)
Secondary (multiple blood transfusions, ineffective erythropoiesis, increased iron intake)
Neonatal (develops in utero, unknown cause)
What are 3 complications to hemochromatosis?
Liver cirrhosis, skin pigmentation, and DM
What is the normal Hgb content in adults?
14 g/dL in females
15.5 g/dL in males
There are four types of Hgb chains: alpha, beta, delta, and gamma. What does the type of chain indicate?
Binding affinity
Each gram of Hgb combines with ______ mL oxygen
The average male contains _____ Hgb per 1 dL blood.
How many mL of O2 can be carried in 1 dL of blood?
What about at 97% saturation (avg)?
1.34
15
- 1
- 5
What effect does anemia have on oxygen carrying capacity and percent saturation?
Decreases O2 carrying capacity, but not necessarily percent saturation
Oxygen ____________ = max amount of oxygen that can be carried by hemoglobin in blood
Capacity (20.1 mL/dL)
Oxygen ___________ = how much oxygen is actually being carried by the blood
Content (19.5 mL/dL)
Oxygen __________ = spots occupied by oxygen as a percentage of total available spots
Saturation
What effect does ATP generated by glycolysis have on RBCs?
Improves membrane flexibility, ion transport, prevents oxidative damage, and maintains iron in Fe2+ form
[If iron is in Fe3+ state it impacts the ability to bind O2]
The erythrocyte life cycle ends when they rupture in the ________; the released Hgb is ingested by __________ immediately
Heme is converted to ________
Peptides go to ________
Iron goes to ________
Spleen (red pulp); monocytes/macrophages
Bilirubin (liver)
Amino acid metabolism
Transferrin (recycling)
Anemia results from a reduction of the total circulating red cell mass below normal limits – often identified as reduced _________ and _________ concentration
Hematocrit; Hgb
What are some characteristics of primary polycythemia?
Genetic (low EPO) Extra RBCs Increased total blood volume Increased blood viscosity Normal cardiac output
What are some characteristics of secondary polycythemia?
Hypoxia (high EPO)
Extra RBCs
Cardiac output may be abnormal
What are some characteristics of physiologic polycythemia?
High altitude adaptation
Extra RBCs
Normal cardiac output
Which form of polycythemia may manifest with an abnormal cardiac output?
Secondary
Which type of polycythemia affects blood volume and viscosity?
Primary
What condition is characterized by iron remaining in ferric form, resulting in decreased O2 availability to tissues and chocolate-colored blood?
Methemoglobinemia (increased methemoblobin)
