Flashcards in MEH - The Spleen Deck (38):
What is 'red pulp' in the spleen?
Sinuses lined by endothelial macrophages and cords. Red cells pass through this preferentially
What is 'white pulp' in the spleen?
Similar structure to lymphoid follicles. White cells pass through this preferentially
Does an enlarged spleen cause pain in most cases?
No, it usually causes a feeling of fullness
What are the functions of the spleen in adults?
- sequestration and phagocytosis (old/abnormal red cells removed by macrophages)
- blood pooling (platelets and red cells can be rapidly mobilised during bleeding)
- extramedullary haemopoiesis (pluripotential stem cells proliferate during haematological stress/if bone marrow fails)
- immunological function
How should splenomegaly be palpated?
Start to palpate in right iliac fossa and feel the edge of the spleen move towards your hand on inspiration. Feel for splenic notch and measure in cm from costal margin in mid-clavicular line
Give some reasons for splenomegaly
- back pressure, eg due to portal hypertension in liver disease
- overworking red/white pulp
- extramedullary haemopoiesis
- expanding as infiltrated by foreign material/cells eg cancers, sarcoidosis
What are the three categories of splenomegaly?
Massive, moderate and mild
What is hyposplenism?
Lack of functioning splenic tissue - may be due to splenectomy, sickle cell disease, coeliac disease.
What is a risk of hyposplenism?
Patients are at risk of overwhelming sepsis, particularly from encapsulated organisms, eg. Pneumococcus
What are Howell Jolly bodies?
DNA remnants seen inside cells on a blood film which appear as dark spots. They suggest that the spleen has been removed.
What is cytopenia?
Umbrella term for a reduction in the number of blood cells.
What is the difference between anaemia and erythrocytosis?
Anaemia = low red cell count
Erythrocytosis = high red cell count
What is the difference between leucopenia and leucocytosis?
Leucopenia = low white blood cells
Leucocytosis = high white blood cells
What is the difference between neutropenia and neutrophilia?
Neutropenia = low neutrophil count
Neutrophilia = high neutrophil count
What is the term for a high lymphocyte count?
What is pancytopenia?
Low red blood cells, white blood cells and platelets
What is the difference between thrombocytopenia and thrombocytosis?
Thrombocytopenia = low platelet count
Thrombocytosis = high platelet count
How do neutrophils appear on a slide?
Stain pink, have 3-5 segments
What does the hormone G-CSF do?
- increases production of neutrophils
- decreases time to release of mature cells from bone marrow
- enhances chemotaxis
- enhances phagocytosis and killing of pathogens
How long do neutrophils live for?
Why might recombinant G-CSF be injected post-chemotherapy?
Increases amount of neutrophils, so can reduce neutropenic infections
Give some examples of things which may cause neutropenia
- B12/folate deficiency
- infiltration of bone marrow by malignancy/fibrosis
- aplastic anaemia
- drugs (chemotherapy, antibiotics, anti-epileptics etc.)
- viral infection
- congenital disorders
What are the roles of monocytes?
- respond to inflammation and antigenic stimuli
- migrate to tissues where they become macrophages and phagocytose pathogens
What is contained within lysosomes in monocytes?
Lysozyme, complement, interleukins, arachidonic acid, CSF
What may cause monocytosis?
Chronic inflammatory conditions, chronic infection, carcinoma, leukemias
How long do eosinophils live for?
8-12 days, of which 3-8 hours are spent in the circulation
What are the roles of eosinophils?
- deal with some parasites
- mediator of allergic response
- migrate to epithelial surfaces
- phagocytosis of antigen-antibody complexes
- mediate hypersensitivity reactions
What is contained in the granules of eosinophils?
Arginine, phospholipid, enzymes
How do eosinophils appear histologically?
Stain pink with two purple central segments
What can cause eosinophilia?
- allergic diseases, eg. asthma
- drug hypersensitivity
- parasitic infection
- skin diseases
How do basophils appear histologically?
Stain purple, look a bit like blackberries. They are the largest immune cell
When are basophils active?
In allergic reactions and inflammatory conditions
What is contained within the granules of basophils?
Histamine, heparin, hyaluronic acid, serotonin
How do lymphocytes appear histologically?
Stain pink with a large pink/purple centre
Give some reactive causes of lymphocytosis
- viral infections
- bacterial infections
- stress related (MI/cardiac arrest)
Pnacytopenia can result due to increased removal of blood cells. Give some reasons for increased removal
Immune destruction, splenic pooling, haemophagocytosis
What is aplastic anaemia?
Pancytopenia with a hypocellular bone marrow in the absence of an abnormal infiltrate and with no increase in reticulin