Blood Cells Flashcards
Where are blood cells made?
Bone marrow.
Lifespan of neutrophil
7-10 hours.
What are blood cells derived from?
Pluripotent haemopoietic stem cells
What is haemopoiesis?
Formation and development of blood cells.
What are the two essential characteristics of HSC’s?
Some daughter cells remain as HSC’s and so pool of HSC’s isn’t depleted. Can follow a differentiation pathway.
Sites of haemopoiesis throughout life?
Yolk sac. Liver (principal source of blood in foetus) and spleen. Bone marrow.
What regulates Haemopoiesis?
Genes, transcription factors, growth factors and microenvironment.
Disruption to the regulation of haemopoeisis can cause what? How can regulation be disrupted?
A disturbance in the balance between proliferation and differentiation which can lead to leukaemia or bone marrow failure.
What is erythropoiesis?
Production of red blood cells.
Where is TPO produced?
Liver.
What does TPO (Thrombopoietin) do?
Stimulates megakaryocyte and platelet production.
What do G-CSF, G-M CSF do?
Stimulate granulocyte and monocyte production.
What does the word ‘blast’ mean?
Immature. Erythroblast = immature red blood cell.
What would you see if you stain erythroblasts with methylene blue?
Will appear blue due to RNA content but erythrocytes wouldn’t appear blue.
Name of condition if you have lots of reticulocytes?
Polychromasia.
What is required for erythropoiesis?
Iron, Folic acid, Vitamin B12 and Erythropoietin
What is microcytic anaemia?
Small red blood cells.
What is macrocytic anaemia?
Large red blood cells.
What causes microcytic anaemia?
Iron deficiency or a reduction in iron availability.
What causes an iron deficiency?
Blood loss, insufficient intake, increased requirement.
What causes Macrocytic anaemia?
B12, folic acid deficiency, liver disease or ethanol toxicity..
What is erythropoietin?
A growth factor that is required in erythropoiesis.
Where is erythropoietin produced?
Kidney.
When is erythropoietin produced?
In response to hypoxia to boost red blood cell production in order to carry oxygen to tissues. In response to anaemia.
Which is the best absorbed form of iron?
Ferrous (Fe2+)
How is the amount of iron in the blood controlled?
Iron absorption is controlled. Liver stores a small amount. Most of the iron is recycled (creation and destruction of red blood cells).
What destroys red blood cells?
Splenic macrophages.
What does hepcidin do?
Blocks absorption of iron and blocks release of storage iron from the liver.
When is hepcidin released?
In response to high storage iron in the liver.
What happens when iron storage is low?
Hepcidin production is downregulated. More iron is absorbed and released from iron storage in liver.
What controls rate of erythropoeisis?
EPO increases rate. Low levels of iron (due to hepcidin) and proinflammatory cytokines (IL6, TNF, IFN) decrease rate.
What causes megaloblastic anaemia?
A deficiency in vitamin b12 and folic acid.
How is megaloblastic anaemia caused?
Vitamin b12 and folic acid are required for DNA synthesis. Needed for Deoxythymidine triphosphate. One of the four nucleoside triphosphates in DNA.
What do you see in megaloblastic anaemia?
Red blood cells grow in size but can’t divide.
What causes a b12 deficiency?
Inadequate intake. Malabsorption. Lack of stomach acid.
How is B12 absorbed?
Gastric parietal cells release intrinsic factor (IF) which binds to B12. IF - B12 complex is absorbed.
What is pernicous anaemia?
Destruction of gastric parietal cells. No release of intrinsic factor and so no absorption of B12
Breaking down of haem group gives?
Bilirubin (excreted in bile).
Breaking down of globin gives?
Amino acids (reused).
What affects red blood cell function?
Cellular metabolism, Integrity of the membrane ,haemoglobin structure and function
Why is red blood cell biconcave structure important?
Increased manouverability in capillaries.
What is the cause of spherocytes?
Disruption in vertical linkages - spectrin and ankyrin
Spherocyte feature on blood film?
Lack central pallor. Round, regular outline.
What is the cause of eliptocytes?
Disruption in horizontal linkages.
What causes eliptocytes to be present in blood?
Hereditary Elliptocytosis. Iron deficiency
Why is G6PD important?
Protects red blood cells from oxidation by producing glutathione.
What can G6PD deficiency cause? What can you see in a blood film?
Severe intravascular haemolysis. Bite cells.
What are heinz bodies?
Clumps of irreversibly denatured hemoglobin seen in bite cells when you stain with methylene blue.
What is polycthaemia?
Too many red blood cells.
Polycthaemia causes?
Blood doping, High altitude, Splenomegaly (due to hypoxia), kidney carcinoma and polycthaemia vera.
Difference between polycthaemia vera and polycthaemia?
Polycthaemia vera is independent of EPO. Myeloproliferative disorder.
MCV equation?
Hct (l/l) *1000 / RBC
MCH equation?
Hb / RBC
MCHC equation?
Hb/Hct
What is anaemia?
Reduction in haemoglobin.
Two principle causes of anaemia?
Failure of production or destruction of red blood cells.
What is poikilocytosis?
Abnormal-shaped red blood cells in the blood.
Low iron blood test result?
Low ferritin and high transferrin.
Thalassaemia key markers.
Raised HBA2, increased RBC, normal MCHC, normal Hb (slightly decreased).
Anaemia of chronic disease markers?
High CRP, high ferritin (due to increased hepcidin in inflammatory state) and low transferrin.
What is Thalassaemia?
Defect in globin.
Tests for macrocytic anaemia?
Liver function test. B12 and folic acid tests.
What does polychromasia indicate?
Haemolytic anaemia (destruction of red blood cells).
What can be observed in megaloblastic anaemia?
Hypersegmented neutrophils.
Sickle cell disease markers?
Increased HbS and HbF and no HbA. Increased reticulocytes. Low Hb.
What may a sickle cell patient require?
Prophylactic antibiotics as they are functionally hyposplenic. Folic acid supplements as there is increased red cell turnover.
Normocytic anaemia causes?
Gastrointestinal haemorrhage, bone marrow failure or hypersplenism.
Polycthaemia risks?
Thrombosis.
When may howell jolly bodies be present in a person’s blood?
Hyposplenic individuals such as sickle cell disease patients.
What are leukocytes derived from?
Myeloblast.
What are the granulocytes?
Neutrophil, Eosinophil and basophil.
What does a neutrophil look like?
Multilobed ( 3-5 lobes).
What does an eosinophil look like?
Pink colour. Bi-lobed.
What does a basophil look like?
Very granulated. Bi-lobed.
What does a monocyte look like?
Kidney shaped lobe.
What pathogen do neutrophils target?
Bacteria and fungi.
What are eosinophils involved in?
Parasite infections and allergens. Regulate type I hypersensitivity by inactivating histamines and leukotrienes.
What are basophils involved in?
Allergy. Type I hypersensitivity.
Basophils and mast cell difference?
Basophils are in circulation while mast cells are tissue resident.
How do basophils modulate inflammatory responses?
By releasing heparin and proteases.
What does transient leukocytosis indicate?
Infection.
What does persistent leukocytosis indicate?
Blood cell disorder.
What cell has the biggest impact on white blood cell count?
Neutrophils.
Causes of neutrophilia?
Infection, inflammation, tissue damage and CML.
Normal physiological causes of neutrophilia?
Pregnancy and excercise.
What may neutrophilia be accompanied with?
Left shift (increase in non segmented neutrophils). Toxic granulation.
What are non segmented neutrophils called?
Band forms.
What is toxic granulation?
Present when there is an increase in the number of large cytoplasmic granules within circulating neutrophils.
Neutropenia causes?
Chemotherapy, radiotherapy, autoimmune disorders or severe infection.
Eosinophilia causes?
Parasitic infection or allergy. CML.
Basophilia causes?
CML.
Monocytosis causes?
Infection or chronic inflammation.
Lymphopenia causes?
HIV, radiotherapy, chemotherapy or use of corticosteroids.
Transient low lymphocyte cause?
Severe infection.
Persistent high lymphocyte cause?
Chronic lymphocytic leukaemia.
Leukemia symptoms?
Hepatomegaly, splenomegaly and leukocytosis.
What would be seen in acute lymphoblastic leukemia?
Lymphoblasts.
What would be seen in acute myeloid leukemia?
Myeloblasts.
What would be seen in chronic lymphocytic leukemia?
Mature lymphoid cells.
What would be seen in chronic myeloid leukemia?
Mature myeloid cells
Most abundant cytoskeletal protein in erythrocytes?
Spectrin.
What does hepcidin bind to in the duodenum?
Ferroportin.
