Blood 2 Flashcards
What are the main causes of bleeding and thrombosis?
Bleeding:
- Injury
- Chronic e.g. in ulcers and diverticular disease
- Liver disease (as the liver produces clotting factors)
- Vitamin K disease
- Drugs
- Infection/sepsis - DIC
- Aneurysm rupture
- Low platelet count (Thrombocytopenia)
- coagulation deficiencies e.g. haemophilia A
Thrombosis:
In the arteries:
- Atherosclerosis
In the vein:
- Cancer
- Surgery
- Immobilisation - pooling of the blood in the lower extremities, which can lead to thrombosis
- Hyper coagulability - usually a genetic factor
- Thrombocythemia
What does the suffix ‘-(p)enia’ suggest? Give an example
A decrease
anaemia - decrease in red blood cell number
Leukopenia - decrease in white blood cell number
Thrombopenia - decrease in number of platelets
What does the suffix ‘-cytosis’ suggest? Give an example
Increase in number
Erythrocytosis - Increase in red blood cell number
Leukocytosis - increase in white blood cell number
Thrombocytosis (also Thrombocythemia) - increase in number of platelets
Describe how haematological malignancies can be classed
Classified according to blood cell lineage:
- myeloid neoplasm
- lymphoid neoplasm
Also categorised according to their location:
- Leukaemia (blood)
- Lymphoma (Lymph nodes)
What is neoplasia caused by?
- Uncontrolled cell growth
- Oncogenes
- Mutated tumour suppressor genes
Describe the prognosis of leukaemia
- Leukaemia result in the accumulation of white blood cells.
- As a result the blood becomes less viscous, leading to problems with circulation.
- Since lots of WBC are being produced, less RBC and platelets are being produced in the bone marrow. As a result oxygen carrying capacity and coagulation capacity is reduced.
- Eventually the bone marrow goes into bone marrow failure and so the individual is prone to infection.
- Result in anaemia as less RBC are being produced.
- Prone to bleeding as not enough platelets are being produced.
How can lymphoma be classified?
Lymphoma is due to the over production of T and B lymphocytes, and NK cells.
Non-Hodgkin lymphoma - Linked to the Epstein-Barr Virus. This virus causes chronic fatigue and is difficult to get rid of. Some families are more susceptible to the virus and so more susceptible to this form of lymphoma.
Hodgkin Lymphoma - Caused by other infections mainly viral but not linked to the EBV. Leads to over enlarged B cells that do not function properly.
What are the main causes of acquired anaemia? How can these be recognised on a blood film?
Main causes of acquired anaemia is iron deficiency, anaemia of chronic disease (renal), folate and vitamin B12 deficiency.
Iron deficiency - microcytic anaemia. cells are pale and small due to reduced haemoglobin production
Vitamin B12 or Folate deficiency - Megablastic or macrocytic anaemia. The red blood cells are large, deformed and not functioning.
What is the role of erythropoietin?
Erythropoietin is a growth factor made by the kidney that signals the myeloid common progenitor to differentiate into red blood cells.
(For platelets it is thrombopoietin - it is the ratio of these factors that tell us which cells are produced and how much)
What is haemolytic anaemia?
Anaemia that results in the break down of red blood cells.
What is the main differences between iron deficiency and folate or vitamin B12 deficiency
Iron deficiency: Required for haem. Insufficient iron means, insufficient haemoglobin is produced and so the RBC cannot function properly. The main cause is dietary - others include blood loss, infection and growth spurts)
Vitamin B12 and folate need to be acquired form the diet. Deficiency of either causes problems with mitosis of the proerythroblast. This causes megablastic or microcytic anaemia. Common in alcoholics, malnutrition, malabsorption and certain drugs.
Describe causes for acquired and inherited haemolytic anaemia
Acquired caused:
- Maleria
- Sepsis
- Reaction to blood transfusion
- Drug induced
- tumours
- cancers e.g. chronic lymphocytic leukaemia and non-Hodgkin’s lymphoma
- Viruses
Inherited causes:
- Glucose-6-phosphate dehydrogenase (G6PDH) deficiency
- Autoimmune haemolytic anaemia
Discuss the underlying mechanisms which cause sickle cell anaemia
A point mutation in gene coding for the beta globin. A Glutamine is swapped for a Valine residue. As a result, the protein is mis-folds to fold a sickle shape and a sticky surface is produced. The misshaped red blood cells polymerise and clog small blood vessels.
Describe the cause of a sickle cell crisis
The polymerised red blood cells clog the arteries, this leads to the tissue becomes anoxic. This causes extreme pain. These crises last for around 20 days as this is how long the sickle cells last in the blood before being removed at the spleen.
What are the difference between the different forms of haemoglobin (foetal, adult)?
Foetal hemoglobin is composed of two α chains and two γ chains, in contrast to adult hemoglobin, which contains two α and two β chains. This difference results in fetal hemoglobin having a higher oxygen affinity than adult hemoglobin.
