Normal RBCs Flashcards
What component of RBC carries O2
Hb
RBC do/not have a nucleus
do not
RBCs do/not have mitochondria
do not
What does a high SA:V ratio allow for in the RBC
gas exchange
What is a consequence of RBC being packed with Hb
creates a high oncotic pressure - cell wants to swell
O2 rich environment - risk of oxidation and damage
consequence of no mitochondria in RBC
energy production limited to glycolysis
- low energy yield
what is special about the RBC membrane
it is complex
contains proteins which make it flexible
How is water kept out of RBCs
via Na/K ATPase
this requires energy
Describe the structure of Hb
tetrameric globular protein
2 alpha and 2 beta chains - globin
haem = Fe2+ and porphyrin ring
O2 can bind to Fe3+, true or false
FALSE
O2 can only bind to Fe2+
What are the chemical symbols for ferrous and ferric
ferrous = Fe2+ ferric = Fe3+
what is the function of Hb
carry oxygen to tissues
acts as a buffer for H+
involved in CO2 transport
which hormone regulates RBC production and from where is it secreted
erythropoeitin
kidneys
where and what happens in RBC destruction
occurs in spleen
macrophages take up aged cells
raw materials are recycled
what is the pathway in the breakdown of haem
haem biliverdin unconjugated bilirubin conjugated bilirubin urobilinogen - urine stercobilinogen - stool
what can the presence of free radicals cause
oxidation of Fe2+ to Fe3+ meaning it cant carry O2
causes damage to proteins
what is the Embden-Meyerhof pathway also known as
Glycolysis
ATP production in the absence of O2
what is the overall net gain in glycolysis
2 ATP + NADH
what molecule is used to prevent oxidation of Fe2+ to Fe3+
NADH (proton donor)
What are reactive oxygen species
give examples
free radicals containing unpaired electrons - damaging
superoxide and hydrogen peroxide (H2O2)
which enzyme converts superoxide into H2O2
superoxide dismutase
what does catalase do
convert H2O2 into H20
what is the function of Glutathione (GSH)
protects us from H2O2by binding with it to form H20 and an oxidised side product GSSG
How does GSSG become GSH again
via NADPH
How is NADPH generated
via hexose monophosphate shunt
which enzyme is the rate limiting enzyme in the hexose monophosphate shunt
G6PD
How is CO2 transported to the lungs
10% dissolved in solution
30% bound to Hb
60% as bicarbonate
Cl- entry into RBC causes it to swell/shrink
swell
Cl- exit from RBC causes it to swell/shrink
shrink
what is partial pressure of a gas
pressure that a gas (in a mixture of gases) would exert if it were alone
how many O2 molecules bind to Fe2+ in haem
1
how many O2 molecules bind in 1 RBC
4
at the lungs, pO2 is high/low
high
Hb needs to bind easily
at the tissues, pO2 is high/low
low
Hb needs to release O2
What pattern is shown when O2 binds to haem
allosteric effect
what is cooperative binding
binding of 1 O2 molecule makes it easier to bind the next etc…
For the same pO2, you will saturate more HbF than HbA, true or false
true
what is the shape of the curve in HbA binding
sigmoid curve
in which pathway is 2,3 BPG generated
Rapapoport-Lubering Shunt
what activates the Rapapoport-Lubering Shunt
chronic hypoxia and anaemia
increase 2,3 BPG levels
high levels of: H+ 2,3BPG temperature causes a shift to the left/right?
right
low levels of: H+ 2,3BPG temperature causes a shift to the left/right?
left
more oxygen is delivered to tissues in times of stress for example
anaemia, metabolic acidosis, increased CO2 concentration
