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67 Cards in this Set
- Front
- Back
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Haemoglobin |
is a haemoprotein composed of haem which gives red blood cells its characteristic colour |
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Function of haemoglobin |
transports oxygen from the lungs to the body tissue |
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Structure of adult human haemoglobin |
Tetramer 4 polypeptide chains(2 unlike pairs) 2 alpha chains 2 beta chains Each globin chains has iron containing molecule called harm in an hydrophobic cavity |
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Function of haemoglobin |
Carries oxygen around the body Iron(Fe) has ability to bind oxygen Unloads oxygen changing from Fe++(ferrous state) to Fe+++(ferric state) and back again |
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How many haemoglobin molecules do each red blood cell contain |
640 million haemoglobin molecules |
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Red blood cells carry out gaseous exchange by |
passing repeatedly through microcirculation(300 miles in its 120 day lifespan) close contact with tissues Maintain haemoglobin in reduced ferrous state(Fe++) Maintain osmotic equilibrium |
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Red cell can fulfil the function of gaseous exchange because |
the red cell is a biconcave disc generates energy as ATP through Embden-Meyerhof pathway generate reducing power as NADPH through hexose-monophosphate pathway |
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Iron plays |
a vital role in normal function/metabolism in almost every cell in the body Essential for haemoglobin production |
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Transferrin |
transports iron to developing red cells which has transferrin receptors |
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Transferrin receptor |
transports iron to developing red cells which have transferrin receptors |
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Ferritin(stored iron) |
66% body iron stored as ferritin 33% stored as haemosiderin stored in liver, pancreas, spleen and bone marrow |
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Average western diet contains |
10-15mg iron daily |
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Iron absorption |
5-10% absorbed through the small intestine Iron from animal products is more readily absorbed than vegetable iron Dietary iron-makes up from daily loss of 1mg in hair, skin, urine, faeces and menstrual blood loss |
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Sources of dietary iron are |
Red meat-Liver Fish-Salmon, sardines, pilchards, tuna Egg yolk Wholemeal bread Breakfast cereals Vegetables and pulses Nuts and prunes Marmite, fortified foods |
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Normal red cells |
Enucleate 6.7-7.7um Biconcave disc Central area of pallor 1/3rd of red cell diameter |
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What is anaemia? |
It is a below normal level of haemoglobin |
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Haemoglobin normal range for adult males is |
130-170g/l adult males |
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Haemoglobin normal range for adult females is |
120-155g/l adult females |
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Anaemia is classified by |
the size of red cells Microcytic-small red cells(MCV<78fl) Macrocytic-large red cells(MCV>100fl) Normocytic-normal size red cells(MCV-78-100fl) |
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Microcytic anaemias |
Iron deficiency Thalassaemia Other haemoglobin defects Anaemia of chronic disease |
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Macrocytic anaemias |
1)Megaloblastic anaemia 2)Non megaloblastic |
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Megaloblastic anaemia |
Folic acid deficiency B12 deficiency Auto-immune disease-pernicious anaemia |
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Non-megaloblastic anaemia |
Myelodysplastic syndromes(MDS) Liver disease |
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Normocytic anaemia |
Haemolytic anaemia Acute blood loss Anaemia of chronic disease |
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Iron deficiency anaemia |
Most common cause of anaemia worldwide(25% world population) Reduced MCV(mean cell volume) Reduced MCH(mean cell haemoglobin) Small red cells Pale/empty red cells |
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What is the cause of iron deficiency anaemia? |
Supply of iron doesn't meet demand Long time to use up body iron stores(ferritin) |
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What are the 3 causes of iron deficiency anaemia? |
1)Iron replete 2)Iron deplete 3)Iron deficient |
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What are the causes of iron deficiency anaemia? |
Chronic blood loss-Menorrhagia, gastrointestinal Increased demands-growth, pregnancy Malabsorption-post gastrectomy Poor diet-A contributory cause |
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What are the clinical features of iron deficiency anaemia? |
Pallor, sore mouth, brittle nails, dysphagia, glossitis, abnormal disease, hair thinking, lassitude, fatigue, tachycardia |
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What are the laboratory findings for iron deficiency anaemia? |
Hypochromic microcytic anaemia Raised platelet count Bone marrow shows-absence stored iron, erythroblasts with ragged irregular cytoplasm Reduced serum ferritin level Low serum iron level Raised serum transferrin receptor |
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What is the treatment for iron deficiency anaemia? |
Oral iron 3 times daily Reticulocyte response within 7 days 4-6 months treatment IV for malabsorption patients |
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Oral/IV iron can cause |
abdominal pain, diarrhoea or constipation |
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Vitamin B12 (Cobalamin) consists of |
cobalt atom situated in the centre of a nucleus |
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Vitamin b12 is a coenzyme for which 2 biochemical reactions |
1)Methylation of homocysteine to methionine 2)Converts methylmalomyl coenzyme A to succinyl coenzyme A |
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What happens without these 2 biochemical reactions? |
Body has a reduced supply of precursors of: 1)DNA synthesis 2)Myelin production |
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What are the effects of DNA synthesis on red cell production? |
Maturation arrest-Erythroblasts in bone marrow show abnormal maturation Maturation of nucleus delayed relative to the cytoplasm No reticulocytes are produced |
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B12 intake |
1ug adult daily requirement of B12 intake Normal mixed diet contains 10-15ug |
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Where is B12 stored? |
B12 is stored in the liver-enough for 2-4 years |
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Where is B12 absorbed? |
It is absorbed in the ileum attached to intrinsic factors which are secreted in the stomach |
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How is B12 transported and lost? |
It is transported in the plasma bound to transcobalamin. It is lost through urine, faeces and the excretion of bile |
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What are the dietary sources of B12? |
Liver, kidney, heart, clams, oysters, red meat, seafood, eggs, milk, cheese, yoghurt, fortified foods |
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What causes B12 deficiency? |
1)Inadequate diet-vegans 2)Malabsorption-Gastrectomy/intrinsic factor deficiency 3)Intestinal causes-tapeworm, crowns disease, ill resection 4)Excess utilisation-pregnancy, haematological disease 5)Liver disease 6)Drug treatments |
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What are the clinical features of B12 deficiency(megaloblasts anaemia)? |
Gradual onset of anaemia Mild jaundice Glossitis Tingling in feet/hands Difficult in gait Visual disorders Psychiatric disorders Asymptomatic (could be) |
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What are the laboratory findings of a B12 deficiency? |
Macrocytic anaemia with oval red cells No reticulocytes Hypersegmented neutrophils Moderately reduced WBC count and platelet count Raised bilirubin Low serum B12 Hyper cellular bone marrow-maturation arrest Raised serum methylmalonic acid/homocysteine levels |
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What is the treatment for B12 deficiency(megaloblastic) anaemia? |
1 mg hydroxycobalamin intramuscularly Every 3 days until 6 injections have been given Every 3 months of life-till deficiency cause is treated Potassium supplements are given same time as B12 (in severe cases) |
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What is Vitamin B12 neuropathy? |
Subacute degeneration of the cord |
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Affects lower limbs in the main |
tingling feet, difficulty walking, falls, optic atrophy, psychiatric symptoms |
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What is the cause of Vitamin B12 neuropathy? |
Accumulation of homocysteine and methionine in nervous tissues Defective methylation of myeline Causes abnormal fatty acids to form around cells and nerves |
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What is pernicious anaemia? |
Autoimmune disease Affects more females than males 1:6:1 Common in over 60 Found in all races Most common in northern europeans |
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What happens in pernicious anaemia? |
Auto antibodies attack the gastric parietal cells Parietal cells secrete intrinsic factors Cannot absorb B12 Increased incidence in carcinoma of stomach |
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What is folic acid(Vitamin B9)? |
Pteroglutamic acid A parent compound of a large group of compounds called folates Humans can't synthesise folic acid |
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What happens to folic acid(Vitamin B9)? |
Its heat labile-destroyed by cooking Absorbed in jejunum Body stores only 3 months |
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What diseases is the folic acid(Vitamin B9) deficiency often seen? |
Coeliac disease Tropical sprue Crohn's disease |
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What is the role of folic acid in the body? |
Needed for a variety of biochemical reactions homocysteine-methionine serine-glycine synthesis of DNA precursors |
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Why do you need folic acid? |
Its necessary for production of new cells Deficiency hinders DNA synthesis/cell division Its also a substrate in the important reactions that involve B12 |
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What are the sources of folic acid? |
Leafy veg-spinach Turnip Lettuce Beans Peas Breakfast cereals Fruit-Banana, Melon, Lemon Liver |
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What are the clinical features of folate deficiency? |
Same as B12 deficiency(but less severe)
Gradual onset of anaemia Mild jaundice Glossitis Tingling in feet/hands Difficult in gait Visual disorders, Psychiatric disorders Asymptomatic (could be) |
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What is the cause of spina bifida(neural tube defect opening in spinach cord/brain)? |
B12 or folic acid deficiency in early pregnancy Lower maternal serum B12 or folate Buildup of homocysteine or in foetus Impairs methylation of various proteins and lipids |
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What is the treatment of spina bifida? |
Dietary supplements in early pregnancy reduce incidence by 75% |
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What are the tissue abnormality associated with B12/folic acid deficiency? |
Sterility(either sex) Morphological abnormalities of cervix, bladder, other epithelia Cleft lip and palate in the foetus/newborn -Folate supplements at time of conception and early pregnancy Widespread reversible melanin pigmentation Cardiovascular/malignant disease |
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What is Normocytic anaemia? |
Its when there's not enough normal size red cells(MCV in normal range) |
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What are the causes of normocytic anaemia? |
Acute blood loss Premature destruction of red cells(Haemolytic anaemia)-sickle cell, hereditary spherocytosis, autoimmune disease Chronic disease-Rheumatoid arthritis, cancer, kidney disease, drug treatment |
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What is haemolytic anaemia? |
Anaemias that result from the increased rate of red cell destruction Classified as hereditary |
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What is hereditary haemolytic anaemia? |
Red cell membrane defects-spherocytosis, Elliptoctosis Defective red cell metabolism-G6PD deficiency, pyruvate kinase deficiency Disorders of haemoglobin synthesis-sickle cell, thalassaemia |
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What happens in acquired haemolytic anaemias? |
Extra corpuscular-haemolytic disease of the newborn Autoimmune haemolytic anaemia DIC Heart valve replacements Environmental-drug induced, march haemoglobinuria, malaria/e. coli |
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What are the clinical features of acquired haemolytic anaemia? |
Pallor Mild fluctuating jaundice |
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What are the laboratory findings for acquired haemolytic anaemia? |
Features of increased RBC breakdown-Bilirubin raised, LDH raised, Haptoglobin reduced, Reticulocytosis, Bone marrow erythroid hyperplasia Damaged red cells-morphology shows fragments, microspherocy, elliptocytes |
