All lectures Flashcards
Glycolysis is the ____ step in the breakdown of glucose to extract energy.
first
Glycolysis does not use ?
Oxygen
Describe the first phase of glycolysis
First traps the glucose molecule and uses energy to modify it: the six-carbon sugar molecule is split into two three-carbon molecules
Describe the second phase of glycolysis
The second extracts energy from the molecules and stores it in the form of ATP and NADH (one enzyme is pyruvate kinase)
What do reactive oxygen species do?
- Converts ferrous of haemoglobin to ferric of methaemoglobin
- Damage lipid membrane: short life span
What does glutathione do?
Scavenges reactive oxygen species
- Oxidized form is regenerated by glutathione reductase
- Hexose monophosphate shunt generates the necessary NADPH and uses G6PD
What is EPO or erythropoietin?
The hormone which controls red cell production: it works on red cell precursors in the bone marrow and promotes differentiation
EPO is produced where?
Kidney under hypoxic stress
Where is EPO produced in the foetal and perinatal period?
Liver
Where is EPO produced in adults?
Kidney
What is the definition of anaemia?
- Reduction in red cell number and haemoglobin concentration of blood
- Haemoglobin is the oxygen carrying pigmented protein in red cells
- Consequently anaemia is important as it results in a reduction in the oxygen carrying capacity of the blood
Symptoms of anaemia
- Tiredness, headaches
- Dizziness
- Shortness of breath
- palpitations
- Chest pain
What are signs of anaemia?
- Pallor: conjunctivae, palmar creases
- Cardiac decompensation: tachycardia, postural hypotension, congestive cardiac failure
Which signs of anaemia which provide a clue to aetiology?
- Angular stomatitis, glossitis, koilonychia
- Jaundice
- Underlying illness: systemic illness, primary bone marrow pathology
How is anaemia defined by laboratory indices?
Reduction in red cell number and haemoglobin concentration of blood
Useful laboratory indices for anaemia ?
- Haemoglobin (Hb)
- Mean corpuscular volume (MCV)
- Blood film
- Reticulocyte count
Describe properties of full blood count or FBC
- EDTA anticoagulated venous blood sample
- Objective
- Accurate and reproducible
- Rapid
How is haemoglobin measured?
Aliquot lysed by laurel sulphate, read by sphectrophotometry @ 540 nm
How is Red blood cell count measured?
Directly measured by particle counter (impedance: passage of cell impedes current and creates a pulse)
How is mean corpuscular volume measured? (MCV)
Directly measured electronically (impedance)
How is MCHC measured?
Calculated from haemoglobin and haematocrit
How is haematocrit measured?
Calculated from red cell number and MCV
How are white cells and platelets measured?
Measured optically via electrical impedance, light scatter, fluorescence and laser
Haemoglobin levels in pregnancy?
10-20 lower due to disproportionate rise in plasma and red cell volumes
Normal haemoglobin levels (g/L) in newborn?
145-220
Normal haemoglobin level (g/L) in 3-6 months?
110-135
Normal haemoglobin levels (g/L) in 6-12 years?
115-155
Normal haemoglobin levels in males?
130-170
Normal haemoglobin levels in females?
120-160
Normal reference range for MCV?
80-100
Reduced MCV means?
Microcytic anaemia
Normal MCV means?
Normocytic anaemia
Increased MCV means?
Macrocytic anaemia
Purpose of blood film?
- It validates machine cell counts and indices
- Looking for specific morphological findings
Blood smears are?
Dried and stained
Principle of Romanowsky stains?
- Basic cellular elements react with an acidic dye (eosin) and stain red-orange, e.g. haemoglobin
- Acidic cellular elements react with a basic dye (methylene) and stain blue, e.g. nuclear DNA
Describe journey of red cell development
- proerythroblast
- Basophilic erythroblast
- Polychromatic erythroblast
- Pyknotic erythroblast
- Reticulocyte
- Mature red blood cell
Length of bone marrow proliferation and maturation?
3-5 days
Length of reticulocytes from bone marrow to blood?
3-4 days
How long does a mature red cell circulate for?
120 days
What nutrients are required for DNA synthesis and nuclear maturation?
Vitamin B12 and folate
What are reticulocytes ?
- Young immature red cells
- Residual RNA
- Therefore they have a blue blush
- On a blood film this is called polychromasia
Reticulocyte count is identified by?
Staining residual RNA
Manual way of identifying reticulocyte count?
Residual RNA precipitated and stained with a supravital dye (New methylene blue) and manually counted)
Automated way of counting reticulocyte?
Residual RNA stained with fluorescent dyes (green) and enumerated by flow cytometry
Reference range of reticulocyte count ?
50-100 x 10^9 / L or 0.5-2.0%
List cause of anaemia
- Decreased production: deficiencies of iron, B12, folate
- Systemic illness, primary bone marrow pathology
- Increased loss of blood (bleeding)
- Shortened life span or increased destruction (haemolytic anaemias), either inherited (e.g. thalassaemias) or acquired autoimmune)
Anaemia with decreased or increased white cells and/or platelets due to primary bone marrow pathology when?
When more than one cell line is abnormal
Anaemia is NOt a?
Diagnosis
MCV < 80fL means?
Iron deficiency due to chronic blood loss.
Inherited Hb abnormality: the thalassaemias
MCV normal means?
- Acute blood loss
- Systemic illness
- Primary BM pathology
MCV > 100 fL means?
- B12 and folate deficiency
- Haemolysis
- Liver disease
What is anisopoikilocytosis?
Iron deficiency anaemia. Hypochromic microcytic cells.
In B12 or folate deficiency, what happens to RBCs?
Macrocytes
Spherocytes occurs?
Haemolysis
What happens in polychromasia?
Abnormally high number of immature red bloo cells
What happens in sickle cell anaemia?
An inherited abnormal haemoglobin, aren’t enough red blood cells to carry oxygen because they’re mishapen and break down faster than normal.
Rouleaux disease is?
RBCs stacking together due to discoid shape and flat surface. Occurs in myeloma
What happens in acute leukaemia?
Immature white blood cells (blast cells) continue to divide but doesn’t mature
Increased reticulocytes means?
Increased bone marrow production
What can increase bone marrow production?
- Acute haemorrhage
- Reduced red cell life span: haemolysis
- Response to replenished iron, B12 and folate
Normal or reduced reticulocytes means?
Reduced bone marrow production
What can reduce bone marrow production?
- Not enough iron, B12 and folate
- Systemic illness
- Bone marrow pathology
Iron studies can test for?
Transferrin saturation and ferritin
Haemolytic screen can test for?
- Bilirubin, LDH, haptoglobin, DCT
Tests of inherited causes of haemolysis look at?
Haemoglobin, red cell membrane and red cell enzymes.
Lab test for creatinine looks at?
Renal impairment
Serology tests look for?
Autoimmune diseases
Liver function tests look for? (LFT’s)
Hepatic dysfunction
Which diseases should be considered when primary bone marrow pathology is diagnosed? (more than one cell line is affected)
- Leukaemia
- Lymphoma
- Myeloma
- Myeloproliferative disease
- Secondary carcinoma
Bone marrow biopsy are performed to?
Confirm or exclude a suspected diagnosis
Procedure of bone marrow biopsy?
- Site: posterior iliac crest or sternum, tibia in neonates
- Aspirates: to assess cell number, maturation and morphology
- Trephine: to assess cellularity, architecture and abnormal cellular infiltrate
Treatments of anaemia?
- Transfusion: only indication is circulatory compromise: acute severe blood loss, circulatory failure especially in the elderly
- Replace missing iron, B12 and folate
- Rectify shortened life span, in case of haemolysis
- Treat underlying condition
Life span of neutrophils?
3-4 days unless digesting bacteria
Life span of eosinophils?
3 weeks
Life span of basophils?
3-10 days
Life span of B cells?
4 days to 5 weeks
Life span of T cells?
Couple days to months
Life span of monocytes?
1 week
Life span of platelets?
7-10 days
Lymphoid stem cells develop into?
Lymphoblast, which then develops into:
- B lymphocyte
- T lymphocyte
- Natural killer cells
Myeloid stem cells develop into?
- Red blood cells
- Platelets
- Myeloblast which develop into: granulocytes (basophils, eosinophils, neutrophils)
0-2 months foetus blood production?
In yolk sac
2-7 months foetus blood production?
Liver, spleen
5-9 months foetus blood production?
Bone marrow
Infants blood production where?
Mostly bone marrow (long and flat bones)
Adults blood production where?
- Bone marrow in all regions of flat bones and extremities of long bones (e.g. vertebrae, ribs, sternum, skull, sacrum and pelvis, proximal ends of femur)
- Extra-medullary depends on need
Mature RBC does not have?
- No DNA
- No RNA
- Cannot synthesize Hb
Reticulocytes does not have?
- Doesn’t have nucleus,
- Reduced size
- Still contains some RNA
Reticulocyte moves into peripheral blood and final maturation by?
Repeated passage through spleen/marrow in peripheral blood circulation ~ 48 hours
Orthochromatophilic erythroblast/normoblast haemoglobin percentage?
35%
What are basophilic erythroblast?
Nucleus condensing, haemoglobin formation
What are polychromatophilic erythroblast?
Cells getting smaller, losing organelles, nucleus shrinking, producing Hb
Haemoglobin is broken down into ?
Globin and heme, and amino acids.
Heme becomes bilirubin, which is?
Bilirubin is picked up from blood by liver, secreted into intestine in bile, metabolized to stercobilin by bacteria and excreted in feces.
Iron is stored as?
Ferritin and haemosiderin in liver
Essential factors of erythropoiesis?
- Hypoxia inducible factors
- Haematinics (e.g. b12, cobalamin, B9, folic acid/folates, iron - transferrin - macrophages
Control of erythropoiesis:
- Hypoxia, anaemia
- Thyroid hormones, androgens, growth hormone, corticosteroids
Essential organs of erythropoiesis?
- Bone marrow
- Kidney, liver, spleen, gastrointestinal
Destruction of erythrocytes?
Macrophages, haem breaks down to iron and bilirubin (colour)
Critical biosynthesis in erythropoiesis?
DNA synthesis, Hb synthesis
Causes of iron deficiency anaemia?
- Increased iron requirements: growth demands
- Limited external supply: poor intake, malabsorption
- Blood loss: bleeding, venesection
Stain for haemoglobin?
Hb is basic component, so use acidic dye (eosin) - red/orange .
Stain for DNA?
DNA is acidic, so use basic dye (methylene) - blue
MCV is?
Mean corpuscular volume or the average volume of red cells.
Causes of microcytic anaemia?
- Iron deficiency anaemia
- Thalassaemia (genetic disorder, abnormal Hb)
Describe vitamin b12 absorption
- Dietary B12 intake,
- Dietary protein separated from B12 due to HCl and pepsin secretion
- Haptocorrin binds to B12 protein
- Complex goes to intestine where B12 binds to intrinsic factor
- B12- intrinsic factor complex binds to cubman receptor which then allows it to separate, and be absorbed through MDR1 channel into blood vessels.
Vitamin B12 or folate deficiency leads to?
Macrocytic anaemia due to impaired DNA synthesis
Lack of Vitamin B12 or folate are caused by?
- Insufficient intake
- Deficient absorption: due to gastrectomy and/or autoimmune attack such as pernicious anaemia
Causes of normocytic anaemia?
- Decreased production: anaemia of chronic disease (common)
- Increased destruction or loss: acute bleeding, hypersplenism, haemolytic disorders
- Increased plasma volume: pregnancy
What are the prevalence of anaemia?
- ~8% of preschool children
- 12% of pregnant women
- 15% of non-pregnant women of reproductive age
- Highly prevalent in Indigenous communities
Symptoms of anaemia? (subjective phenomenon)
- Tiredness
- Dizziness
- Palpitation
- Headache
Signs of anaemia (objective phenomenon)
- Pallor: conjunctivae, skin, oral mucosa
- Jaundice
- Koilonychia (spoon nails)
What does atrophic glossitis look like? (due to anaemia)
- Smooth glossy appearance with red or pink background tongue
What does angular cheilitis as a oral manifestation of anaemia?
- Inflamed and cracked skin at the angles of the mouth