Session 3- Haemopoesis, the Spleen and Bone Marrow Flashcards
what is haemopoiesis
production of blood cells in the bone marrow
bone marrow extensive throughout the skeleton in infant
where is bone marrow found in adults
pelvis sternum skull ribs vertebrae
what are HPSC
haemopoietic stem cells
capable of self-renewal
can differentiate into variety of speacilised cells
not normally seen in the blood
what is the RES
reticuloendothelial system
part if immune system and made up of monocytes in blood and a network of tissues which contain phagocytic cells ]
role: to remove dead or damaged cells and identify and destroy foreign antigens in blood and tissues
main organs of RES
spleen and liver
what is the spleen made up of
red pulp- sinuses lined by endothelial macrophages and cords- where RBCs go through
white pulp- similar structure to lymphoid follicles- white cells and plasma preferentially pass through the white pulp
function of 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 haemopoesis- pluripotent stem cells proliferate during haematological stress or if marrow fails
immunological function- 25% of T cells and 15% of B cells are present in spleen
how does blood enter the spleen
splenic artery
what is splenomegaly
abnormal growth of the spleen
what causes splenomagaly
back pressure- portal hypertension in liver disease
over work- red or white pulp
reverting to what it used to do- extramedullary haemopoesis
expanding as infiltrated by cells- cancer cells or metastases
expanding as infiltrated by other material- sarcoidosis - granuloma
how do you examine the spleen
it is never normal for the spleen to be palpable below the costal margin
start to palpate in Right Iliac Fossa
feel for spleen edge moving towards your hand on inspiration
feel for splenic notch
measure in cm from costal margin in mid-clavicular line
what causes massive splenomegaly
chronic myeloid leukaemia
myelofibrosis
malaria
schistosomiasis
moderate splenomegaly
lymphoma leukaemia myeloproliferative disorders liver cirrhosis with portal hypertension infections such as Glandular fever
and everything for massive splenomegaly
mild splenomegaly
infectious hepatitis
endocarditis
infiltrative disorders such as sarcodosis
autoimmune diseases
hypersplenism
low blood counts can occur due to pooling of blood in enlarged spleen
hyposplenism
lack of functioning splenic tissue or no spleen
howell-jolly inclusion bodies- DNA remnants
risk of sepsis from encapsulated bacteria
- streptococcus pneumonia
- haemophilus influenzae
- meningococcus
patients must be immunised and given life long antibiotic prophylaxis
causes of hyposplenism
splenonectomy
sickle cells disease
gastrointestinal disease
autoimmune disease
degradation of haem
senescent red blood cells engulfed by macrophages in reticuloendothelial system
components broken down
the iron from Haem is recycled
haem converted into unconjugated bilirubin
bilirubin diglucoronide by being conjugated with glucoronic acid then secreted in Bile into duodenum
bilirubin converted to urobilinogen which is subsequently oxidised to sterocobilin which is comes out in faeces
some urobilinogen absorbed into blood and transported to kidney. Oxidised to Urobilin and excreted in urine
cytopenia
a reduction in the number of blood cells
cytosis or philia
increase in the number of blood cells
neutrophilia
increase in absolute number of circulating neutrophils
causes
- infection
- myeloproliferative diseases
- Cytokines- G-CSF
- tissue damage
neutropenia
low white cell count causes reduced production -B12/ folate deficiency -aplastic anaemia -viral infection -congenital -infiltration -radiation -drugs
increased removal or use
-sepsis
-immune destruction
splenic pooling
consequences of neutropenia
severe life threatening bacterial infection
severe life threatening fungal infection
mucosal ulceration
monocytosis
increase in monocytes
- bacterial infections
- carcinoma
- myeloproliferative disorders and Leukaemia
