T2 L1: Erythrocytes Flashcards
Describe the effect of pO2 on how oxygen will bind to haemoglobin
High pO2 means more oxygen binds to Hb. It will detach when the pO2 is low
Why does oxygen need haemoglobin to enable its transport?
Because oxygen in poorly soluble in plasma. Normal arterial blood carries 70x more oxygen on haemoglobin than dissolved directly in plasma
How many molecules of ATP are produced at the end of oxidative respiration?
36
What is produced in anaerobic glycolysis and how many molecules of it?
2 lactate and 2 ATP
What % of dry weight of red blood cells is haemoglobin?
95%
What are the allosteric properties of haemoglobin with O2?
When the first oxygen binds, the affinity increases
Where is myoglobin found?
In muscles
What charge is unbound Iron ion in haemoglobin?
2+
What is HbA and what is its structure?
Adult haemoglobin (maternal haemoglobin). It’s a tetramer made of 2 alpha and 2 beta subunits
What is HbF and what is its structure?
Foetal haemoglobin. It’s made up of 2 alpha and 2 gamma subunits
Describe the Bohr effect on oxygen binding when pH is low
Low affinity of Hb for O2, high for CO2
Where does O2 bind to Hb compared to CO2 and H+?
At a different site of Hb
What % of CO2 is dissolved in blood?
10%
What % of CO2 is as carbamino Hb?
22%
What % of CO2 is as HCO3-?
68%
What is a Band 3 protein and what is its function?
A membrane exchange protein that allows bicarbonate to leave in exchange for Cl-
What is HHb?
Acidified Hb (has a H+)
Where is a higher concentration of Cl- inside RBC’s, in venous or arterial blood?
In venous blood
What type of curve does myoglobin have on a partial pressure and fractional saturation graph?
A hyperbolic curve (very steep)
What type of curve does heamoglobin have on a partial pressure and fractional saturation graph?
A sigmoidal (s-shape)
What does a rightward shift indicate about the affinity for oxygen?
Decreased affinity
What 4 molecules encourage a rightward shift of affinity in muscles?
Increased presence of CO2, H+, Cl- and Bisphopho-glycerate
Why does a rightward shift of Hb affinity happen in muscles?
To lower affinity so that O2 can dissociate from haemoglobin
What is the function of Bisphospho-glycerate (2,3-DPG) in red blood cells?
It facilitates O2 dissociation by binding to Hb and lowering its affinity for O2 (causing a rightward shift)
Why does Foetal Hb (HbF) have a higher affinity for O2?
Because it has a low affinity for 2,3-DPG (Bisphospho-glycerate) compared to maternal blood so a rightward shift is not achieved as easily.
What is a myoglobin?
A storage molecule for O2 found in muscles
In active muscles low O2, high CO2, high blood acidity, high temperature and myglobin cause what to happen?
O2 leaves Hb, CO2 and H+ bind to Hb, HCO3- leaves RBC’s and Cl- leaves plasma
Why is the body more sensitive to changes in CO2 compared H+?
Because the H+ signal is only based from the carotid arch but there are more signals for CO2
Concentrations of which molecules control breathing rate?
O2, CO2 and acid concentration
What is the main driver to increase respiratory rate and why?
H+ in CSF. Because once CO2 gets into the CSF, it reacts to produce carbonic acid and H+. Not in the blood because CO2 gets into CSF slower so it’s a better indication of higher acidity
Why must plasma O2 drop significantly before the respiratory drive increases?
Because we are not very sensitive to [O2]. So a bigger change is needed for the body to realise
What is meant by anucleate?
Lacking organelles
What is the height and diameter of erythrocytes?
7 micrometres diameter, 2 micrometres height
How long do erythrocytes survive?
About 100-120 days
What is the advantage of erythrocytes being flexible?
They can fold in vessels and stack
What is the packed cell volume in men compared to women?
40-52% in men, 36-48% in women
What is the mean cell haemoglobin (MCH) in normal blood?
27-34 picograms
After the age of 20, where are erythrocytes produced?
In membranous bones only like vertebrae
Where are erythrocytes produced during embryogenises (4 places)?
Liver, spleen, lymph nodes and yolk sac
What are the steps of development of stem cells?
Multipotent stem cells continue self renewing but some become progenitor cells. Those progenitor cells commit to a lineage and proliferate. Then they all terminally differentiate into mature cells
What are progenitor cells?
Stem cells that are slightly differentiated and can only develop into cells from only that tissue or organ
Which part of erythrocyte production is erythronmycin dependent?
Before the stem cells develop into erythroblasts
Which part of erythrocyte production is iron dependent?
When Erythroblasts are developing into reticulocytes
What happens during maturation when the red blood cells are reticulocytes?
The cells are getting rid of their nuclear material
What is Erythropoetin?
A cytokine/hormone that drives erythropoiesis
Where is Erythropoetin produced?
In the kidney in a hypoxia-inducing way
How long do reticulocytes last in the blood?
2 days and then becomes a definitive RBC
How can a reticulocyte count be used as a diagnostic tool for anaemia?
It’s an indicator of bone marrow activity. The reticulocyte count is low when erythrocyte concentrations are low. The reticulocyte count is high in haemolytic anaemias
What is methaemoglobinaemia and what causes it?
A disease when Hb can’t transport O2 because Fe in Hb is oxidised into Fe3+ when it should be Fe2+. It’s caused by congenital globin mutations, hereditary decrease of NADH and toxic substances
What is CO poisoning and what is the treatment?
When CO displaces O2 from Hb. The treament is 95% O2 and 5% CO2 (CO2 helps to knock off CO so O2 can displace it)
How much stronger is CO’s affinity for HB compared to O2?
x250
What is cyanosis?
When blood turns blue
What is Polycythaemia?
A high concentration of RBC’s (PCV) leading to thick blood that clogs blood vessels
What causes physiologic Polycythaemia?
Living in high altitudes
What causes Polycythaemia vera?
A cancer that’s often asymptomatic. Causes an increased risk of thrombotic events with no cure other than taking blood away (venesection). The chances of developing it increase with age
What % of iron is stored intrinsically as ferritin or haemosiderin?
30%
What is ferritin?
A protein that stores and releases iron in a controlled way
What is Haemosiderin?
An iron storage molecule composed of partially digested ferritin and lysosomes
In what cells and organs is Fe stored in the form of ferritin?
In the liver, spleen, erythromycin, bone marrow and macrophages/monocytes
What is the normal daily loss of iron?
About 1 mg/day
What dificiency causes megaloblastic (macrocytic) anaemia
Vitamin B12 and B9 (folic acid)
What is the cause of pernicious anaemia?
Failure to absorb Fe (Intrinsic)
What cells are sensitive to Folic and B12?
All quickly dividing cells
What causes hypochromic microcytic anaemia?
Iron deficiency (the cells continue living but cannot fill up with Hb)
