L1 Flashcards
Oxygen is poorly soluble in plasma. How much more O2 can haemoglobin carry than is directly dissolved in plasma?
70x more
How many ATP is formed via anaerobic respiration in rbcs?
2 ATP
What percentage of a rbc is Hb?
95% dry weight
Each haemoglobin and myoglobin subunit has 1 haem group. Describe the structure of a haem group. (4)
porphyrin ring
2D
coloured (because of e- sharing and is NOT due to Fe2+)
bound to ferrous ion (Fe2+)
How many O2 molecules per haem?
1
Describe adult/maternal Hb (HbA)
2 alpha subunits
2 beta subunits
Describe foetal haemoglobin’s structure and properties (HbF)
2 alpha subunits
2 gamma subunits
binds O2 more strongly than adult haemoglobin
Why does an increase in blood CO2 level decrease the affinity of Hb for O2?
more CO2 = less O2 in cells -> less muscle contractions -> Hb encouraged to release O2 for muscle contraction
Why does a decrease in blood pH decrease the affinity of Hb for O2?
more acidic environment -> damaging to cells -> Hb encouraged to release O2 to raise blood pH to normal level
Give the equation for the formation of carbonic acid
H2O + CO2 –> H2CO3
What % of CO2 is:
dissolved?
transported as carbamino?
transported as HCO3-?
10%
22%
68%
Explain how CO2 can be transported in the blood as HCO3-
CO2 enters and combines with H2O to form H2CO3
this is broken down to H+ and HCO3-
HCO3- then exchanged for Cl- via the band 3 protein (chloride-bicarbonate exchanger)
Explain the chloride shift
(Chlorine hates gas)
(at the lungs) O2 enters rbc -> Cl- leaves and enters surrounding blood
(at the muscles) CO2 enters surrounding blood -> Cl- enters rbc
For O2 binding, describe the myoglobin curve and the haemoglobin curve
myo: hyperbolic/exponential
haemo: sigmoidal
Describe the effect of 2,3-diphosphopglycerate in HbA vs HbF
binds to Hb and lowers its for O2 for HbA but not HbF
Give the dimensions of a rbc in micrometers
diameter: 7 micrometers
height: 2 micrometers
In terms of the respiratory drive, why is the response to CO2 > than the response to H+ in the blood?
the signal in response to H+ in the blood is from the carotid arch
What is the mean corpuscular volume (mcv) value?
80-100 fL
What is the mean cell haemoglobin (mch) value?
27-34 per gram
What are the Hb values for male and female?
male: 13-17 g/dL
female: 12-16 g/dL
What are the values for the haemocrit/packed cell volume (pcv) for male and female?
male: 40-52%
female: 36-48%
Define erythropoiesis and distinguish where it occurs after birth and after age 20.
development of rbcs
after birth: bone marrow only
after 20: primarily central bones (eg vertebrae)
Where does erythropoiesis occur during embryogenesis? (4)
liver
spleen
lymph nodes
yolk sac
Describe the steps involved in rbc production from stem cells (4 steps)
hint: 1st step= multipotent stem cells
multipotent stem cells ->multipotent myeloid progenitor cells -> lineage-committed progenitor cells -> mature cells
What is erythropoietin and state its role.
cytokine made in the kidney that drives erythropoiesis
What are reticulocytes, how long do they last in the blood and what can they be used to diagnose?
precursors to rbcs
2 days
haemolytic anaemia
What is methaemoglobinaemia and what causes it?
Fe2+ is oxidised to Fe3+ so Hb cannot transport O2
congenital globin mutations (Hb M)
hereditary decrease of NADH
toxic substances
Describe what happens in CO poisoning and why is it lethal?
Hb cannot transport O2 as CO is bound to its binding site
it is lethal as the PO2 dissolved in blood remains normal so typically undetected until disorientation (as the brain is affected first)
Vitamin B12 and folic acid: role? deficiency caused by? deficiency leads to? treatment?
role in thymidine in DNA formation, important in rbc’s, skin production and gametogenesis
diet, malabsorption, increased utilization, pregnancy
megaloblastic (macrocytic) anaemia
oral folic acid, intramuscular hydroxocobalamin
Fe can be stored as ferritin and haemosiderin. Where can Fe be stored?(5)
liver spleen erythrocytes bone marrow macrophages/monocytes
Describe what occurs during polycythaemia
affecting all ages, this occurs due to living at high altitudes
rbc count increases and blood viscosity increases
