Red blood cells Flashcards
What are the key characteristics of an erythrocyte? (3)
Biconcave disc
Large surface are
Favours diffusion - thin (2um)
What is the main feature of an erythrocytes membrane?
Very flexible - pass through capillaries easily
What are the 3 states an erythrocyte can be in and how are they caused?
Hypotonic - cell swells and loses shape
Characteristic shape - normal bi-concave disc
Hypertonic - cells collapse but rigid cytoskeleton stays intact
How many Hb molecules can a single RBC hold?
250,000,000 (250 million)
What is the structure of a RBC? (4)
5 million per ul
7-8 um dimater
No nucleus
No organelles
Without any organelles or nucleus, how do RBC survive?
RBC’s cannot grow, repair or divide
They survive off supplies they synthesised before the nucleus was excluded - 120 days
Where are RBC’s originally made? (haematopoiesis)
Yolk sac - fetus
Liver/spleen - baby in mother
Bone marrow - alive
What is bone marrow like?
Highly vascularised, where erythropoiesis occurs
What is the spleens role in the erythrocyte life cycle?
recycling components of the red blood cell
Broken down to HEME and GLOBIN
HEME to iron and bilirubin
GLOBIN to A.A.
What is the livers role in the erythrocyte life cycle?
Turns bilirubin to bile - excreted
What are the kidneys role in the erythrocyte life cycle?
Monitor O2 levels and release erythropoietin if a decrease occurs
What does erythropoietin do when released into the blood?
Stimulates erythropoiesis by the bone marrow
Increase O2 carrying capacity in RBC
What is globing made of?
4 highly folded polypeptide chains
What is the haem group structure?
4 iron containing, non-protein groups bound to the polypeptides
How does CO2 travel around the body?
Bind reversibly to polypeptide chains
Carbonic anhydrase in erythrocytes
CO2 + H2O = H2CO3 = H+ + HCO3-
