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MEH > 5. Haemopoeisis, Spleen And Bone Marrow > Flashcards

5. Haemopoeisis, Spleen And Bone Marrow Flashcards

1
Q

Where does the production of blood cells occur?

A

Bone marrow
In adult: pelvis, sternum, skull, ribs, vertebrae
In infant: extensive throughout skeleton

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2
Q

What is differentiation of haemopoietic stem cells determined by?

A

Hormones
Transcription factors
Interactions with non-haemopoietic cell types

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3
Q

What is the role of erythropoietin?

A

Secreted by kidney and stimulates red blood cell production

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4
Q

What is the role of thrombopoietin?

A

Produced by liver and kidney and regulates production of platelets

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5
Q

What are the 2 progenitor cell types?

A

Common myeloid

Common lymphoid

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6
Q

What do common myeloid progenitors differentiate into?

A

Megakaryocytes (platelets)
Erythrocytes
Myeloblasts

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7
Q

What do myeloblasts differentiate into?

A

Basophils
Neutrophils
Eosinophils
Monocytes -> macrophage

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8
Q

What do common lymphoid progenitors differentiate into?

A

Small lymphocytes

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9
Q

What do small lymphocytes differentiate into?

A

B lymphocytes

T lymphocytes

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10
Q

What are the features of haemopoietic stem cells?

A

Capable of self-renewal

Given appropriate stimuli can differentiate into variety of specialised cells

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11
Q

What is extramedullary haematopoiesis?

A

In pathological conditions such as myelofibrosis or thalassaemia haemopoietic stem ells can mobilise into circulating blood to colonise other tissues

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12
Q

What is the reticuloendothelial system (RES)?

A

Part of immune system and made up of monocytes in blood and a network of tissues which contain phagocytic cells

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13
Q

What is the role of the RES?

A

To remove dead or damaged cells and identify and destroy foreign antigens in blood and tissues

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14
Q

What are the main organs of the RES?

A

Spleen and liver

RES cells in spleen dispose of blood cells

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15
Q

What are the functions of the spleen in adults?

A

Sequestration and phagocytosis
Blood pooling (platelets and RBC can be rapidly mobilised during bleeding)
Extramedullary haemopoeisis
Immunological function

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16
Q

What can cause splenomegaly?

A

Back pressure - portal hypertension in liver disease
Over work (red or white pulp)
Extramedullary haemopoeisis
Expanding as infiltrated by cells (cancer)
Expanding as infiltrated by other material

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17
Q

What is hypersplenism?

A

Low blood counts occur due to pooling of blood in enlarged spleen

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18
Q

What is hyposplenism?

A

Lack of functioning splenic tissue

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19
Q

What can cause hyposplenism?

A

Splenectomy
Sickle cell disease
Gastrointestinal diseases (coeliac, Crohns, ulcerative colitis)
Autoimmune diseases (systemic lupus, rheumatoid arthritis)

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20
Q

What are Howell Jolly bodies?

A

RBC with DNA remnants - normally removed by spleen

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21
Q

What are patients with hyposplenism at risk of?

A

Sepsis from encapsulated bacteria
E.g. streptococcus pneumonia, haemophilus influenzae, meningococcus
Patients must be immunised and given life long antibiotic prophylaxis

22
Q

What happens when there are changes to the RBC plasma membrane?

A

Causes cell to become less derformable and more fragile

23
Q

What proteins are involved in hereditary spherocytosis?

A

Spectrin
Ankyrin
Band 3
Protein 4.2

24
Q

What is spectrin?

A

Actin crosslinking and molecular scaffold protein that links plasma membrane to actin cytoskeleton

25
Q

What is ankyrin?

A

Links integral membrane proteins to the underlying spectrin-actin cytoskeleton

26
Q

What is band 3 protein?

A

Facilitates chloride and bicarbonate exchange across membrane and also involve in physical linkage of membrane to cytoskeleton (binds wit ankyrin and protein 4.2?

27
Q

What is protein 4.2?

A

ATP-binding protein which may regulate the association of band 3 with ankyrin

28
Q

Describe the degradation of haem

A

Senescent RBC engulfed by macrophage in reticuloendothelial system
Haem is recycled as Fe2+ or converted to bilirubin
Unconjugated bilirubin transported in blood bound to albumin
Some bilirubin taken up by liver ad conjugated with glucuronic acid
Conjugated bilirubin secreted in bile into duodenum
Either into faeces or reabsorbed and excreted in urine

29
Q

What is the conjugated form of bilirubin?

A

Bilirubin diglucoronide

30
Q

What form of bilirubin is in faeces?

A

Stercobilin

31
Q

What form of bilirubin is in urine?

A

Urobilin

32
Q

What is cytopenia?

A

A reduction in the number of blood cells

33
Q

What does …cytosis or …philia at the end of a word mean?

A

An increase in the number of blood cells

34
Q

What are neutrophils?

A

First-responder phagocyte
Most common white cel
Essential part of innate immune system
Circulate in bloodstream and invade tissues (lifespan 1-4 days)

35
Q

What is the maturation of neutrophils controlled by?

A

The hormone G-CSF, a glycoproteins growth factor and cytokine

36
Q

What does G-CSF do?

A

Increases production of neutrophils
Speeds up releas of mature cells from BM
Enhances chemotaxis
Enhances phagocytosis and killing of pathogens

37
Q

When is recombinant G-CSF administered?

A

When more neutrophils are needed

E.g. a patient with severe neutropenia and sepsis after chemotherapy

38
Q

What is neutrophilia?

A

An increase in the absolute number of circulating neutrophils

39
Q

What can cause neutrophilia?

A 
Infection
Tissue damage
Smoking
Myeloproliferative diseases 
Cancer
Acute haemorrhage
40
Q

How does acute haemorrhage cause neutrophilia?

A

Neutrophils usually stick to endothelial cells of vessels

These are released in haemorrhage increasing the number of circulating neutrophils

41
Q

What are the consequences of neutropenia?

A

Severe life threatening bacterial infection
Severe life threatening fungal infection
Mucosal ulceration

42
Q

What causes reduced production of neutrophils and therefore neutropenia?

A 
B12/folate deficiency
Aplastic anaemia
Viral infection
Congential
Drugs
Radiation
43
Q

What causes increased removal or use of neutrophils and therefore neutropenia?

A

Immune destruction
Sepsis
Splenic pooling

44
Q

What are the features of monocytes?

A

Largest cells in blood
In tissues differentiate into macrophages or dendritic cells
Phagocytose microorganism and breakdown/remove cellular debris
Antigen presenting role to lymphocytes
Defence against chronic bacterial infections

45
Q

What are the causes of monocytosis?

A

Bacterial infection
Inflammatory conditions
Carcinoma
Myeloproliferative disorders and leukaemias

46
Q

What are the features of eosinophils?

A

Responsible for immune response against multicellular parasites
Mediator of allergic responses
Granules contain array of cytotoxic proteins
Phagocytosis of antigen-antibody complexes

47
Q

What are the common causes of eosinophilia?

A

Allergic diseases
Parasitic infection
Drug hypersensitivity
Skin diseases

48
Q

What are basophils?

A

Large dense granules containing histamine, heparin, hyaluronic acid, serotonin
Granules stain deep blue
Active in allergic reactions and inflammatory conditions

49
Q

What are the 3 types of lymphocytes?

A

Bc ells
T cells
Natural killer cells

50
Q

What can cause lymphocytosis?

A 
Viral infections
Bacterial infections
Stress related: MI/cardiac arrest
Post splenectomy
Smoking
Leukaemia
Lymphoma

MEH (22 decks)

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