Blood Flashcards
What are the components of blood?
Plasma; clotting/coagulation factors, albumin, antibodies
Buffy coat; platelets, white cells/leucocytes
Red blood cells
What are the functions of blood?
Transport
Maintenance of vascular integrity
Protection from pathogens
Describe transport in blood
Red blood cells transport gases: CO2 and O2
Plasma transports nutrients, waste and messages
Describe blood involvement in maintenance of vascular integrity
Prevention of leaks; platelets and clotting factors
Prevention of blockages; anticoagulants and fibrinolytics
Describe blood involvement in protection from pathogens
Phagocytosis and killing; granulocytes/monocytes
Antigen reception and antibody formation; lymphocytes
What are some haematological abnormalities and how can they occur
High levels;
- raised production
- (decreased rate of loss)
Low levels
- decreased production
- increased rate of loss
Altered function
Describe stem cells
Totipotent
Self-renewal
Home to marrow niche
Binary fission and flux through differentiation pathways amplify numbers
Flux regulated by hormones/growth factors
What is the anatomy of bone marrow?
Where is it?
- bones; mostly in children, axial in elderly
What does it look like?
- stroma and sinusoids
Describe erythroid differentiation
Erythroblast - reticulocyte - erythrocyte
Erythropoeitin; made in kidney in response to hypoxia
Where is erythropoetin made?
kidney
What is the reticulocyte count?
A measure of red cell production
What are consequences of anaemia?
poor gas transfer; dyspnoea, fatigue
What are haematinics?
iron folate vit B12
Deficiency in anaemia
How many RBCs can you make in a day?
~10g/L/day
What is the function of platelets?
Haemostasis and immune
How is production of platelets regulated?
By thrombopoetin
- produced in liver- regulation by platelet mass feedback
- agonists (romiplostim, eltrombopag) used therapeutically
What is the lifespan of platelets?
7 days
What is the function of neutrophils?
Ingest and destroy pathogens, especially bacteria and fungi
Interleukins (between white cells) and CSFs (colony stim factors)
Regualtion by immune responses; macrophages, IL-17
What is the lifespan of neutrophils?
1-2 days
What is the response speed of neutrophils?
few hours
Describe neutrophil differentiation
- Blast
- Promyelocyte
- Myelocyte
- Metamyelocyte
- Neutrophil
When does neutrophilia occur?
Infection
Inflammation; MI, post-op, rheum arthritis
Production regulated by granulocyte-colony stim factor
When is G-CSF used therapeutically?
Granulocyte- colony stim factor
Used in neutropenia and mobilisation of stem cells
What causes neutropenia?
“racial”
Decreased production; drugs, marrow failure
Increased consumption; sepsis, autoimmune
Altered function; chronic granulomatous disease
What are monocytes?
Subset migrate into tissues and become macrophages
Dendritic cells
Function is to ingest and destroy pathogens especially bacteria and funghi
What is the lifespan of macrophages?
many months
What is the lifespan of dendritic cells?
weeks
What are lymphocytes?
Subtypes;
- B cells
- T cells
- NK cells
Circulate in blood, lymph and lymph nodes
Differentiate into effector cells in secondary lymphoid organs; lymph nodes or mucosal associated lymphoid tissue
Describe positive and negative selection
In bone marrow
- if gene rearrangement results in functional receptor cell selected to survive (positive)
- if receptor recognises self antigens cells triggered to die (negative)
Describe human leucocyte antigen
HLA
Class I; displays internal antigens on all nucleated cells (MHCI)
Class II; displays antigens eaten by professional antigen presenting cells (MHCII)
Describe FBC
Haemoglobin RBC Platelets WBC Neutrophils Lymphocytes; monocytes, eosinophils, basophils
What are some infectious causes of splenomegaly
- acute e.g. EBV, CMV
- chronic bactericidal e.g. TB, brucella, SBE
- chronic parasitic e.g. malaria, leishmaniasis, schistosomiasis
