Section 6: RBC structure & function Flashcards
Where is the lipid bilayer located on the red cell?
Function of the lipid bilayer
Outside part the RBCs
-insoluble barrier that separate vastly different environments.
Function of protein membrane skeleton
-gives structure, shape, & deformability
-proteins on surface of cell act as receptors, RBC antigens & enzymes
-contains pumps/ channels for movement of ions b/w interior of the RBC & the plasma
what do Integral proteins do? (give example of one)
they go across the lipid bilayer
ex- sialic acid = gives RBC their negative charge so that they don’t stick together
Peripheral proteins (give example of one)
interact w/ lipids at membrane surface but DON’T penetrate bilayer
ex- spectrin = cytoskeleton which modulates shape & deformability
^ they deform (form biconcave shape) reduce flow resistance
Osmotic balance b/w plasma & cytoplasm in Isotonic vs hypotonic vs hypertonic
-Isotonic (normal) = normal RBC
-Hypotonic (dilute) = RBC swelling
-Hypertonic (concentrated) = shrunken RBC
What are the 4 metabolic pathways of RBCs?
-Embden-Meyerhof pathway
-Hexose monophosphate pathway
-Rapoport - Luebering pathway
-Methemoglobin pathway
Embden - Meyerhof pathway does what in RBCs?
Anaerobic glycolysis = main way RBC gets energy
90-95% of glucose consumption w/ net gain of 2 ATP
Which is the most common enzyme deficiency in the Embden-Meyerhof pathway?
Pyruvate kinase
May result inadequate ATP production? — Dawn clarification
Hexose monophosphate pathway does what in RBCs?
Aerobic glycolysis = combats oxidative injury to RBC
Which is the most common enzyme deficiency in the hexose monophosphate pathway?
A deficiency in (G6PD) can result in Abnormal RBC morphology
Rapoport - Luebering pathway does what in RBCs?
Regulates O2 delivery to tissues
Why is 2,3-biphosphoglycerate (2,3-BPG) an important enzyme?
-important control for Hgb affinity for O2
deficiency can results in inadequate ATP production?
The methemoglobin reductase pathways does what?
Maintains hemoglobin in its reduced (Fe2+) state by reducing Fe3+
Why is methemoglobin reductase enzyme an important enzyme?
It reduces (Fe3+) into (Fe2+) which allows it to carry O2
deficiency can be due to
-hereditary enzyme deficiency
-toxic substance exposure
-abnormal Hgb M disease
What does cyanosis mean?
Met-Hgb can’t carry O2 so the skin gets blue discoloration
Structure of Hemoglobin
- Heme — a protoporphyrin ring (pyrole ring) w/ a central ferrous (Fe2+) iron
- Globin — polypeptide chain w/ (141-146) amino acids
- 1 Hemoglobin-A molecule = 4 heme + 4 polypeptide chains (2 Alpha, 2 Beta)
Note: variations in amino acids create different globin chains
Heme iron
In the ferrous Fe2+ form
Transferrin
Plasma transport protein that carries iron in the ferric form Fe3+
Ferritin
Is (Iron + apoferritin) = major storage form of iron