Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y3 immunology and haematology > red cells 1 > Flashcards

red cells 1 Flashcards

1
Q

what is anaemia

A

reduction in red cells or their Hb content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the causes of anaemia

A

blood loss
increased destruction
lack of production
defective production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what substances are required for red cell production

A

iron, copper, cobalt, manganese

B12, folic acid, thiamine, vit B6, C, E

amino acids

erythropoietin, GM-CSF, androgens, thyroxine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

production of RBC

A

pluripotent stem cell under the influence or erythropoeitin then develop into RBC

eject nucleus just before leaving bone marrow

reticulocyte is the step just before a mature RBC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

where does RBC breakdown occur

A

reticuloendothelial system

- macrophages in spleen, liver, lymph nodes, lungs etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the normal life span of a RBC

A

120 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are RBC recycled into

A

globin –> amino acids –> reutilised

haem

  • iron recycled into haemoglobin
  • haam –> biliverdin –> bilirubin –> bound to albumin in plasma

bilirubin from RBC breakdown before it gets to liver - unconjugated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is an erythrocyte

what is it made up of

A

mature RBC

membrane
enzymes
haemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where can genetic defects in congenital anaemia occur

what do they cause

prevalence

A

defects in cell membrane, metabolic pathways, Hb

most reduce RBC survival, result in haemolysis

carrier states are often silent, prevalence varies geographically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

red cell membrane

A

skeletal proteins are reponsible for maintaining red cell shape and deformability - spectrin and ankyrin

defects can lead to increased red cell destruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the commonest inherited membrane disorder

A

hereditary spherocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what condition is this

A

hereditary spherocytosis

instead of biconcave shape, defect in skeletal protein leads to loss in structure and cells are sphere shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

hereditary spherocytosis - dominant or recessive

A

most common forms are autosomal dominant

strong FHx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

hereditary spherocytosis - protein defects

A

defects in 5 different structural proteins

ankyrin 
alpha spectrin 
beta spectrin
band 3
protein 4.2

all lead to spherocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what happens to the cells in hereditary spherocytosis as a result of their changed shape

A

red cells are spherical

recognised by the body as foreign

removed from circulation by RE system (extravascular - broken down outside the blood vessels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

clinical presentation of hereditary spherocytosis

A

anaemia - red cells aren’t lasting as long

jaundice (neonatal)

splenomegaly - working more than normal

pigment gallstones - bilirubin in plasma is increased so more likely to crystallise in gallbladder

can be an incidental finding w/ very mild symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

treatment of hereditary spherocytosis

A

folic acid - increased requirements

tranfusion

splenectomy - if anaemia very severe; reduces red cell destruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

3 other rare membrane disordes

A

hereditary elliptocytosis

hereditary pyropoikilocytosis

south east asian ovalocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what condition is this

A

hereditary elliptocytosis

less severe than spherocytosis but similar symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what condition is this

A

hereditary pyropoikilocytosis

combination of different proteins involved

can become severley anaemic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does south east asian ovalocytosis present

A

strange, large looking oval red cells

mild clinical picture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the function of glycolysis

A

provides energy

pathway interacts with the pentose phosphate shunt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the function of the pentose phosphate shunt

A

protects from oxidative damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

important link between pentose phosphate shunt and glycolytic pathway

A

glycose 6 - phosphate dehydrogenase

key to red cell survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

where can enzyme deficiencies occur

A

glucose 6 phosphate dehydrogenase - affects both pathways

pyruvate kinase - rarer, only affects glycolytic pathway

26
Q

function of G6PD

A

protects red cell proteins (Hb) from oxidative damage

produces NADPH - vital for reduction of glutathione
reduced glutathione scavenges and detoxifies reactive oxygen species

27
Q

G6PD deficiency

  • how common
  • what happens to cells
  • protection?
A

commonest disease causing enzymopathy in the world
- many genetic variants

cells vulnerable to oxidative damage

confers protection against malaria
- most common in malarial areas

28
Q

inheritance of G6PD deficiency

A

X linked

  • affects males
  • female carriers
29
Q

what condition is this

A

G6PD deficiency

blister cells - top (pooling of Hb)
bite cells

30
Q

clinical presentation of G6PD deficiency

A

variable

variable degrees of anaemia
neonatal jaundice
splenomegaly
pigment gallstones

drug, broad/fava bean or infection (increases free oxygen species) precipitated jaundice and anaemia:

  • intravascular haemolysis - toxins are in the circulation w/ cells
  • haemoglobinuria
31
Q

triggers to haemolysis in G6PD deficiency

A

infection
acute illness e.g. DKA

broad (fava) beans

drugs - lots

32
Q

what drugs can trigger haemolysis in G6PD deficiency

- don’t need to know for exam

A

antimalarials - primaquine, pamaquine

sulphonamides and sulphones - salazopyrin, dapsone, septrin

antibacterials - nitrofurantoin

analgesics - aspirin

antihelminthics - B-naphthol

misc - vit K analogues, probenecid, methylene blue

33
Q

pyruvate kinase deficiency

- effects on cells

A

reduced ATP

increased 2,3-DPG

cells rigid

34
Q

clinical presentation of pyruvate kinase deficiency

A

very rare

variable severity:
anaemia
jaundice
gallstones

can lead to haemolysis

35
Q

what is the structure of Hb

A

2 alpha chains
2 beta chains

4 associated heme molecules - iron surrounded by protoporphyrin ring

36
Q

what is the function of Hb

A

oxygen binding and unloading

changes binding structure when doing this

37
Q

Hb and gas exchange

A

O2 to tissues

CO2 to lungs

38
Q

oxygen dissociation curve

what is the Bohr effect

HbF

A

shifts as a compensatory mechanism

Bohr effect:

  • acidosis
  • hyperthermia
  • hypercapnia

HbF - higher O2 affinity than HbA

39
Q

describe normal adult Hb

A

composed of haem molecule and 2 alpha chains (4 alpha genes, Chr 16), 2 beta genes (2 beta genes, Chr 11)

over the first 6 mths of life the gene expression changes, HbF levels drop

40
Q

what are haemoglobinopathies

A

inherited abnormalities of Hb synthesis

reduced/absent globin chain production - thalassaemia (alpha, beta, delta, gamma)

mutations leading to structurally abnormal globin chain (HbS - sickle cell, HbC, HbD, HbE, HbO Arab…)

41
Q

areas with high prevalence of haemoglobinopathies

A

can occur in any ethnic group

concentrated in areas where malaria is/was endemic

usually because being a carrier allows some level of protection against malaria

42
Q

inheritance of haemoglobinopathies

A

nearly all are autosomal recessive

2 asymptomatic carriers - 1/4 chance of having affected child, 1/2 change of being carrier/trait

43
Q

Hb structure in sickle cell disease

A 
2 normal alpha chains 
2 beta (sickle chains) - point mutation

when the cell goes through hypoxic tissues it becomes sickle shaped as the abnormal Hb polymerises - rigid polymers irreversibly form rigid shapes

44
Q

what condition is this

A

sickle cell (HbSS)

45
Q

pathophysiology of sickle cell

A
  1. Hb S polymerisation
  2. vaso-occlusion
  3. endothelial dysfunction
  4. sterile inflammation
46
Q

inheritance of sickle cell disorder

A

autosomal recessive

one of the commonest inherited disorders worldwide

47
Q

clinical presentation of sickle cell disease

A
  • painful vaso-occlusive crises: bone
  • chest crisis - hypoxia - more sickling - endless cycle
  • stroke - SCD is one of the biggest causes of stroke in children
  • increased infection risk - hyposplenism
  • chronic haemolytic anaemia - gallstones, aplastic crisis
  • sequestration crises - spleen, liver
48
Q

what is an aplastic crisis

A

can occur when erythrovirus infects RBCs, switches of RBC production

Aplastic crisis is defined as a decrease in Hb of 3g/dl or more with reticulocytopenia, usually resulting from parvovirus B19 infection

49
Q

management of sickle cell - painful crisis

A

severe pain - often requires opiates (should be given within 30mins of presentation, effective analgesia by 1hr), avoid pethidine

hydration

oxygen

consider abx

50
Q

life long prophylaxis in sickle cell disease

A

due to lack of splenic function

vaccination
penicillin (and malarial) prophylaxis
folic acid - long term increased requirements

51
Q

management of acute events in sickle cell diseae

A 
hydration 
oxygenation
prompt treatment of infection
analgesia - opiates, NSAIDs
blood transfusion if very anaemic
52
Q

long term management for sickle cell disease

A

blood transfusion - mainstay of management

  • episodic/chronic
  • complications: alloimmunisation, iron overload

disease modifying drugs - hydroxycarbamide (increases HbF, works well for painful crises)

bone marrow transplantation

gene therapy

53
Q

what is alloimmunisation

A

develop alloantibodies against tranfused blood

54
Q

Hb structure in thalassaemias

A

reduced or absent globin chain production

mutations/deletions in alpha genes (alpha thalassaemia)
αα/αα
-α/αα = α+
–/αα = α0 - incompatible with life

in beta genes (beta thalassaemia)

chain imbalance - chronic haemolysis and anaemia

55
Q

spectrum of clinical severity in thalassaemia

A

homozygous alpha zero thalassaemia - no alpha chains, hydrops fetalis (incompatible with life)

beta thalassaemia major (homozygous beta thalassaemia) - no beta chains, transfusion dependent anaemia

non-transfusion dependent thalassaemia - ‘intermedia’ - range of genotypes (HbE/beta thal, HbH disease)

thalassaemia minor (common) - carrier state, hypochromic microcytic red cell indices

56
Q

features of beta thalassaemia major

A

severe anaemia

  • present at 3-6m/o (switch between HbF and HbA)
  • expansion of ineffective bone marrow
  • bony deformities
  • splenomegaly
  • growth retardation

life expectancy untreated/w/ irregular transfusions - <10yrs

57
Q

what condition is this

A

beta thalassaemia major

no normal looking RBCs

nucleated RBCs also present in circulation

58
Q

what is seen here and what condition is it associated with

A

skeletal expansion in the skull
white line = normal boundary of skull
hair on end appearance due to bone marrow expansion

beta thalassaemia major

59
Q

treatment for beta thalassaemia major - transfusion

A

chronic transfusion support - 4-6wkly

normal growth and development
BUT - be aware of iron overloading

death in 2nd-3rd decades due to heart/liver/endocrine failure if iron loading untreated

60
Q

treatment for beta thalassaemia major - iron chelation therapy

A 
s/c desferrioxamine infusions (desferal)
oral deferasirox (exjade)

good adherence to chelation - life expectancy near normal

  • requires regular monitoring
  • ferritin and MRI scans
61
Q

what can be a cure for beta thalassaemia major

A

bone marrow transplantation

62
Q

rare defects in haem synthesis

A

defects in mitochondrial steps of haem synthesis –> sideroblastic anaemia

  • ALA synthesis mutations
  • hereditary
  • acquired (most common) - form of myelodysplasia

defects in cytoplasmic steps result in porphyrias

Y3 immunology and haematology (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions