L12 Haemoglobinopathies

Question 1

why is Hb needed

Answer 1

due to low solubility of oxygen in water

Question 2

what chromosomes is Hb involved with

Answer 2

6 and 11

Question 3

where are chains synthesised

Answer 3

yolk sac in spleen

Question 4

in adults 96-98% Hb is HbA which is 2 alpha and 2 beta subunits

0. 5-0.8is hbF a2y2
1. 5-3.2 is hbA2 a2delta2

oxygen binding to Hb changes the structure of the porphyrin ring from a T ( tense state ) to a relaxed

Answer 4

R state

Question 5

cooperative affect

Answer 5

makes it easier for oxygen to bind

Question 6

o2 dislocation curve - at low pO2 hb carrier little O2 and at higher pO2 the saturation increase due to the increased affinity from the cooperative effect
at high pO2 all harm groups become bound resulting in full o2 saturation

what is the Bohr effect

Answer 6

presence of CO2 causes decrease in hb affinity for oxygen

Question 7

how is co2 transported

Answer 7

dissolved co2
carbamino compounds
bicarbonate ions - most common - breakdown by carbonic acid

Question 8

what make up is fatal haemoglobin

Answer 8

2 alpha and 2 gamma subunits

Question 9

fetuses are dependent on the mother for supply of oxygen so in order to oxygenate the blood of the foetus the blood of the mother must be Abel to transport o2 to the blood of the foetus so

Answer 9

fetal hb has a higher affinity than adult hb at all partial pressures of oxygen on the dislocation curve

as a result it is able to remove oxygen from the adult hb one the fatal and maternal blood run next to each other in the placenta

Question 10

abnormal synthesis of global

Answer 10

sickle cell anaemia

Question 11

reduced synthesis of global

Answer 11

thalassaemias

Question 12

if you have sickle cell disease what can it prevent the severity of

Answer 12

Malaria

Question 13

what is sickle cell anaemia

Answer 13

abnormal hb formation distorting shape of erthrocyte - these then lodge in arterioles and caps clogging them preventing oxygen delivery - leading o pain , weakness, organ damage and even stroke and paralysis
average life span of sickled erythrocyte Is only 20 days

Question 14

sickle cell anaemia has multiple presentations - what are they

Answer 14

vaso-occlusive crises 
visceral sequestration crisis 
aplastic crisis 
haemolytic crisis 
others

Question 15

a vaso-occlusive crisis is caused by dehydration and altitude change and an infarction could be

Answer 15

a stroke

Question 16

visceral sequestration crisis is what

Answer 16

pooling of blood in various organs leaving little cricualtign RBC and therefore anaemia is wore - liver , spleen and lungs affected causing pain and dyspnoea

Question 17

what is an aplastic crisis

Answer 17

fall in reticulocyte hb very low

due to parvovirus B19 , folate or B12 deficiency

Question 18

what is a haemolytic crisis

Answer 18

vasodilation

Question 19

therapy and management of crisis

Answer 19

hydration
warmth
therapy included abc replacement by blood transfusion but also long term to suppress hb lives - treat precipitant , analgesia folic acid, penicillin

Question 20

can thalassamias be classified according to which chain of the globin is affected

Answer 20

alpha - production of alpha globulin is deficient - 4 genes 2 on each chromosome 16 - 2 from each parents

beta - - 2 genes , 1 on each chromosome 11 and 1 from each parent