Erythrocyte Physiology Flashcards
three types of formed elements
white blood cells
red blood cells
platelets
hematocrit
the % of blood that is cells
RBC levels are sensed by the
kidney
- and a little in the liver
HIF-a
- what does it do in high O2 levels
- low O2 levels?
hypoxia inducible factor
- is ubiquinated and destroyed in sufficient O2 state
- accumulates in low O2 state
how does HIF act as a transcription factor
it binds with HIF-b in the nucleus and induces transcription and expression of erythropoietin which is then released in the blood
erythropoietin
principle regulator of erythropoiesis; produced by kidneys –> promotes erythropoiesis in bone marrow
the receptor for erythropoietin is connected to the _____ pathway
JAK2/STAT5 pathway
two requirements for adequate erythropoiesis
- adequate nutrition
- iron availability
microcytic anemia
low iron; smaller hemoglobins; pallor
the acidity of the stomach favors which form of iron
ferric form (Fe3+)
why do deficiencies in B12 and folic acid cause macrocytic anemia
cells are going through cell division but cannot make DNA, but they are still making proteins so the RBCs are getting larger
what do deficiencies cause in:
- iron
- B12
- folate
- microcytic anemia
- macrocytic anemia
- macrocytic anemia
what is the expected amount of oxygen to be carried by hemoglobin
1.34 mL O2 / g Hb
how to calculate oxygen capacity
1.34 mL x g of Hb
how to calculate oxygen content
oxygen capacity x % saturation
(1.34 x g Hb) x % saturation
what do RBCs need for
- flexibility
- ion transport
- maintaining iron in ferrous state
- preventing oxidation of Hb
ATP
how does the body compensate when O2 content is decreased
increased work load on heart; heart pumps more blood
In anemia, how are the levels changed:
- O2 sat
- Hb
- O2 capacity
- O2 content
- blood viscosity
- heart workload
- serum iron
- serum ferritin
- transferrin
- O2 sat unchanged
- Hb reduced
- O2 capacity reduced
- O2 content reduced
- viscosity reduced
- heart workload increased
- serum iron reduced
- serum ferritin reduced
- transferrin increased
in hemochromatosis, how are the levels changed:
- O2 sat
- Hb
- O2 capacity
- O2 content
- blood viscosity
- heart workload
- serum iron
- serum ferritin
- transferrin
- O2 sat unchanged
- Hb normal
- O2 capacity normal
- O2 content normal
- normal viscosity
- cardiomyopathy
- serum iron increased
- serum ferritin increased
- transferring reduced
Polycythemia
too many red blood cells
- thicker blood
- greater workload for heart
physiological polycythemia
low oxygen due to altitude/lung/heart disease
polycythemia vera (primary polycythemia)
bone marrow is making RBC when there is no need to; can be related to mutation in receptor for thrombopoietin
what is primary polycythemia characterized by
- EPO level
- RBC amount
- blood volume level
- viscosity
- cardiac output
genetic low EPO extra RBCs increased blood volume increased viscosity normal cardiac output
what is physiological polycythemia characterized by
- environment
- RBC amount
- cardiac output
high altitude adaptation
extra RBCs
normal cardiac output
what is secondary polycythemia characterized by
- EPO level
- RBC amount
- cardiac output
high EPO
extra RBCs
heart, lungs, vasculature may be abnormal
what does a left shift on the Hb dissociation curve indicate
increase in affinity of Hb for O2
what does a right shift on the Hb dissociation curve indicate
decrease in affinity of Hb for O2
what factors can cause a right shift in the dissociation curve of Hb
high CO2
low pH
increase temperature
2,3-BPG
what factors can cause a left shift in the dissociation curve of Hb
low CO2
high pH
when do we see an increase in CO2 and/or H+, temperature, and 2,3-BPG
exercising
methemoglobinemia
the presence of large amounts of iron in the 3+ state in the heme
- decreased oxygen availability
- left shift on curve
- chocolate colored blood
- easily reversed
what do the kidneys do under low oxygen conditions
produce more EPO
5 factors that decrease oxygenation in the tissues
low blood volume anemia low Hb poor blood flow pulmonary disease
poor B12 absorption due to autoimmune disorder causes
pernicious anemia
folate or B12 deficiency causes
megaloblastic macrocytic anemia
hypochromic anemia is caused by
deficient transport of transferrin to developing erythroblast
microcytic anemia
caused by deficiency in iron
what is the oxygen saturation of blood leaving the lungs
95 mmHg
what shift in the dissociation curve is associated with anemia
right shift
what shift in the dissociation curve is associated with polycythemia
left shift
true/false:
anemia decreases the oxygen carrying capacity but does not affect the percent saturation
true
oxygen capacity vs oxygen content
maximum amount of O2 that can be carried by Hb
amount of O2 that is actually being carried
oxygen saturation
spots occupied by oxygen as a percentage of total available spots
why do RBCs need ATP
- contributes to membrane flexibility
- maintains iron in Fe2+ rather than 3+
- ion transport
- prevents against oxidative damage
released hemoglobin from ruptured RBC going where
it is ingested by monocyte-macrophage cells immediately
