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MEH * > 3.1 Haemopoiesis, The Spleen And The Bone Marrow > Flashcards

3.1 Haemopoiesis, The Spleen And The Bone Marrow Flashcards

1
Q

What is haemopoiesis and where does it occur?

A

Production of blood cells occurs in the bone marrow

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2
Q

What would a biopsy of the pelvis look like?

A

Bony trabeculae with fat cells between them

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3
Q

What makes the haemopoietic stem cell (HPSC) so special?

A
  • can differentiate into RBC

- has the greatest power of self renewal compared to any other adult tissue

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4
Q

What are the sources of HPSC?

A
  • bone marrow

- G-CSF (a hormone that controls haemopoiesis) mobilised stem cells

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5
Q

What is the reticuloendothelial system?

A
  • a network in blood and tissues which is part of the immune system containing phagocytic cells.
  • cells of the RES can identify and mount an appropriate immune response to foreign antigens
  • main organs = the spleen and the liver
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6
Q

What does the spleen consist of and how does this influence blood flow?

A

Red pulp - sinuses lined by endothelial macrophages and cords. Red cells preferentially pass through here.

White pulp - similar structure to lymphoid follicles. White cells and plasma preferentially pass through here.

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7
Q

What is the role of the portal vein in relation to the spleen?

A

Takes look to liver from splenic vein

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8
Q

What is the function of the spleen in adults?

A
  • sequestration and phagocytosis of old/abnormal red cells, removed by macrophages
  • blood pooling - platelets and red cells rapidly mobilised during bleeding
  • extramedullary haemopoiesis - spleen swells and makes blood when bone marrow cant
  • immunological function - has some t and B cells
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9
Q

What is splenomegaly and where may it be felt?

A

Abnormal enlargement of the spleen - never normal to palpate it below the costal margin
Feel in the right iliac fossa

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10
Q

Why would the spleen grow?

A
  • back pressure
  • overworking red pulp
  • over working white pulp
  • reverting to what it use to do (extramedullary haemopoiesis)
  • expanding as infiltrated by cells which should e there e.g cancer cells of blood origin such as leukaemia or by other cancer metastasis.
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11
Q

What part of the spleen do cancer cells of blood origin effect?

A

Expand white pulp

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12
Q 
What could possibly be behind
- massive
- moderate
- mild 
Splenomegaly?
A
  • massive: chronic myeloid leukaemia, myelofibrosis, malaria, schistosomiasis
  • moderate: above as well as lymphoma, leukaemia, liver cirrhosis with portal hypertension, infection such as glandular fever
  • mild: above as well as infections e.g hepatitis, endocarditis, autoimmune disorders, etc.
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13
Q

Why should you avoid physical activity in cases of splenomegaly?

A

Rupture of spleen - can lead to a haematoama or infarction.

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14
Q

What is hypersplenism?

A

Pooling of blood in enlarged spleen(as a result get a low blood count)

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15
Q

What’s a Howell jolly body and where is it found?

A

Will see in hyposplenism

A cluster of DNA in circulating red blood cells.

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16
Q

How is haemoglobin synthesised?

A
  • on chromosome 11 and 16, switches at different stages in life.
  • switch from foetal to adult haemoglobin occurs at 3-6 months of age
  • defect in cell membrane components = red cells less deformable and recognised by the spleen as abnormal = shorter life cycle = haemolytic anaemia
17
Q

How does erythropoietin work in a negative feedback loop?

A
  • patient = anaemic so reduced pO2 detected interstitial cells in kidney
  • increased production of erythropoietin by kidney
  • erythropoietin stimulates maturation and release of red cells from marrow
  • total red cells and so haemoglobin rises
  • more oxygen can be delivered = pO2 rises
  • as a result erythropoietin production falls
18
Q

What is cytopenia and what are the 5 main forms?

A

Cytopenia = reduction in the number of blood cells.

Low red cells = anaemia
Low white cells = leukopenia 
Low neutrophil = neutropenia
Low platelet = thrombocytopenia 
Low red cells, white cella and platelets = pancytopenia

So, ends in -penia, means a reduction

19
Q

What does it mean when a blood syndrome ends with -cystosis or -philia?

A 
An increase in the number of blood cells.
Red cells =erythroytosis
White = leucocytosis 
Neutrophils = neutrophilia
Lymphocytes = lymphocytosis
High platelet count = thrombocytosis
20
Q

What is neutrophil maturation controlled by?

A

Hormone G-CSF
- increases neutrophil production and decreases time to release mature cells from bone marrow

NB: if you need more neutrophils in a patient with severe neutropenia and sepsis after chemotherapy, administer recombinant G-CSF.

21
Q

What can cause neutrophilia?

A
  • cancer
  • acute haemorrhage
  • tissue damage
  • myeloproliferative disorders (marrow working too hard)
  • G -CSF
  • smoking
22
Q

What are the causes of neutropenia?

A
  • b12/folate deficiency
  • infiltration f bone marrow by malignancy or fibrosis = no room for production
  • aplastic anaemia = empty marrow, no precursors
  • radiation = mature cells killed, precursors stunned
  • drugs = poison on the marrow
  • congenital disorders
23
Q

What are the consequences of neutropenia?

A
  • bacterial and fungal infections = life threatening
  • muscles also ulceration

NB: neutropenic sepsis is a medical emergency. Intravenous antibiotics must be given immediately.

24
Q

What is the role of monocytes?

A
  • response to inflammation and antigenic stimuli

- migrate to tissue like macrophages

25
Q

What is monocytosis and what are the causes?

A 
Overproduction of monocytes 
Caused by 
- carcinoma
- chronic infection 
- chronic inflammatory conditions
26
Q

What are eosinophils and how are they distinctive??

A

Eosinophils deal with parasites and are a mediator of allergic response

Look granular with red dots and darker purple dots in the middle

27
Q

What are the causes of eosinophilia?

A
  • allergic diseases e,g, asthma, hay fever, eczema etc.
  • drug hypersensitivity e.g penicillin
  • parasite infection
  • skin diseases

Rarer

  • myeloproliferative disorders
  • Hodgkin lymphoma
28
Q

What are basophils and what makes them distinctive?

A

Active in inflammatory conditions and allergic granules

Are dark, purple and blobby like blackberries. Contain histamine, heparin, hyaluronic acid and serotonin.

29
Q

What are the 3 lymphocytes?

A

B cells
T cells
NK cells

30
Q

What causes lymphocytosis?

A
  • viral/bacterial infections
  • stress related e.g MI
  • post splenectomy
  • smoking
31
Q

Name 3 lymphoproliferative disorders.

A
  • chronic lymphocytic leukaemia
  • T/NK cell leukaemia
  • lymphoma (cells “spill” out of bone marrow)

MEH * (21 decks)

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