Blood Flashcards
How much blood do we have in our body?
5L
What are the phagocytic leucocytes?
1) Neutrophils
2) Eosinophils
3) Monocytes/macrophages
What are the non-phagocytic leucocytes?
1) Lymphocytes
2) Basophils
What is the appearance of a neutrophil?
Multilobed nucleus
Blue Granules
What is the appearance of basophils?
Nucleus obscured by highly granular dark staining cytoplasm
What is the appearance of eosinophils?
Bi lobed nucleus
Pink cytoplasmic granules
‘Tomato wearing sunglasses’
What is the appearance of monocytes and macrophages?
Granular (blue) cytoplasm containing white vacuoles
Nucleus has a characteristic kidney shape
What is the appearance of lymphocytes?
Large nucleus
Very little cytoplasm
Dense purple nuclei, poorly stained cytoplasm
How do neutrophils protect against pathogens and how long do they survive?
Granules contain proteolytic enzymes - break down ingested material
Non specific as dont recognise specific pathogens
Mobile, phagocytic and chemotactic (respond to chemo attractants)
Defence against bacteria and fungi
Survive for 8-10 hours make up 50-70% of leucocytes
How do basophils protect against pathogens and how long do they survive?
Basophils circulate in blood, migrate to tissues and become mast cells
Mast cells possess receptors and when they get a signal spill there granular contents into peripheral blood
Survive 1-5 days, 0-1% of leucocytes
How do eosinophils protect against pathogens and how long do they survive?
Circulate in blood and migrate to tissues where they defend against parasitic infections - certain cytokines (chemicals that affect cell division/production of immune cells) stimulate increased production of eosinophils
Survive circulating in the blood for 4-5 hours and live in tissue for 8-12 days
How do monocytes and macrophages protect against pathogens and how long do they survive?
Monocytes circulate in the blood until they migrate to tissues and become macrophages
Ingest pathogenic material, can kill intracellular organisms and are also professional APC’s
Survive circulating in the blood for 1-3 days but have a long tissue life span
What is the life span of lymphocytes?
Years
What is the appearance of plasma cells?
Granular ‘clock faced nuclei’
Basophilic cytoplasm
Whats the appearance of platelets and whats there lifespan?
No nucleus, small, blue staining
Lifespan of 20 days
What are platelets made from?
Fragments of megakaryocytes that bud off in the bone marrow before entering the blood
What is the most abundant protein in the blood?
Albumin
What is the difference between serum and plasma?
Serum = plasma - clotting factors Plasma = serum + clotting factors (+clotting inhibitor)
How do you extract serum/plasma from the blood?
Using a centrifuge
What happens when incompatible groups of blood are mixed and when does this present a problem?
Ab react with Ag on the surface of the new RBC’s causing haemolysis
This presents a problem for pregnancy and transfusion
What are the 2 main classifications of blood groups?
1) ABO
2) Rh
How is your ABO blood group classified?
Based on a carbohydrate present in the RBC membrane A = Ag A B = Ag B AB = Ag A and AgB O = no Ag
Which ABO blood group is considered a universal donor and a universal recipient?
Universal donor = O
It has no Ag for you to have Ab against
Universal recipient = AB
Blood contains Ag for neither A nor B
Why, in terms of compatibility must you considered blood type when doing a plasma transfusion (not containing RBC’s)?
Because plasma contains Ab so must make sure plasma transfused doesn’t contain Ab to your RBC’s
What are the components of an acute haemolytic reaction (which occurs when incompatible blood is transfused)?
1) Haemolysis
2) Hypotension to keep up with haemolysis
3) Kidney failure - must excrete haem and iron products from haemolysis - haemoglobinuria (free Hb in urine)
4) Systemic symptoms (fever and chills)
5) Pain in lumbar region (loins and lower back)
6) Constricting pain in chest
7) Heat sensation in transfused vein
8) DIC (disseminated intravascular coagulation)
How is youre Rhesus blood group classified?
Based on a transmembrane protein (ion channel) in RBC membrane called D antigen
Rh+ is with the Ag
Rh- is without the Ag
When does haemolytic disease of the newborn occur?
During pregnancy of a Rh+ child to a Rh- woman
Why does haemolytic disease of the newborn tend to present in second pregnancies?
1) Sensitisation - mixing of mothers and foetus blood during birth of the first child which triggers an immune response
2) In future pregnancies, Ab are able to cross the placenta and cause haemolysis in the Rh+ foetus and thus potentially lethal aneamia in the foetus
How can haemolytic disease of the new born be prevented?
Prevention with intramuscular Rh IgG (Ab that mop up Ag) injections at 28,34 and 72 hours after delivery (passive immunity) - can do an intrauterine injection if necessary
What colour do RBC’s and eosinophil granules stain?
Pink/red
What colour do DNA and RNA stain?
Blue/purple
What colour do platelets and other granules (other than eosinophil granules) stain?
Blue/purple
What are the 2 main processes involved in stemming bleeding?
1) Vasoconstriction (peptides/hormones lead to the contraction of smooth muscle cells in the vessel wall eg.
- Thromboxane (produced by platelets)
- Vasopressin (produced by anterior pituitary)
- Angiotensin 2 (precursor produced by liver)
- Serotonin (secreted by activated platelets)
2) Haemostasis
- Primary haemostasis: platelet activation and agregation
- Secondary haemostasis: coagulation pathway activation
What is a thrombocyte?
Another name for platelets
What 2 types of granules do platelets contain?
Alpha granules and dense granules
What is the shape change that platelets undergo when they are activated and what is it?
Pseudopodia
Little extensions from the membrane
Stretch and bind together and from a platelet plug
What structures/substances/enzymes are found within platelets?
Mitochondria: source of ADP for activation
Glycogen: source of energy
Canicular system (invaginations): increased surface area for activation
COX1 and TX synthase: leads to production of thromboxane
What role does thromboxane have in activating platelets?
Auto activation loop
Activated platelets produce thromboxane which further activates other platelets
What type of molecules are ADP and Thromboxane (TxA2)?
Autocrine molecules (secreted by platelets and activate platelets)
What is the ligand for aIIB1 and GPVI receptors and what are they involved in?
Collagen (important for adhesion)
What is the ligand for PAR-1, PAR-4 receptors and what kind of receptors are they and what are they involved in?
GPCR’s
Ligand is Thrombin
Involved in activation
What is the ligand for P2Y1 and P2Y12 receptors and what kind of receptors are they?
GPCR’s
ADP
Involved in activation
What is the ligand for the TP receptor, what kind of receptor is it and what is it involved in?
GPCR
Ligand is thromboxane (TXA2)
Involved in activation
What does the aIIIbB3 receptor bind and what is it important for?
Binds fibrinogen and VWF
Important for aggregation
Platelets in close proximity are able to bind to eachother via fibrinogen and VWF
From what granules in the platelet is ADP released?
Dense granules
What occurs to get the inactivated platelets to bind at the site of injury?
1) No injury - platelet circulate
2) Subendothelial matrix is rich in collagen, when an injury occurs to the endothelium this collagen is exposed and binds to receptors on the platelets activating them aswell as binding platelets at the sight of injury
3) Activated platelets release thromboxane and serotonin which cause local vasoconstriction
4) VWF present in the blood can bind platelets and collagen, fibrinogen binds inbetween platelets all helping to strengthen the platelet plug (once a2B3 receptor is activated)
5) Activated platelets also release ADP, thrombin and thromboxane which serve to recruit and activate other platelets
Although platelets can aggregate and change shape, aggregation is still reversible until what occurs?
Release of granules
What does the word limited in ‘limited proteolysis’ refer to?
The fact that the proteolysis is specific, one type of protein: one cut
What is the difference between the intrinsic and extrinsic coagulation pathways?
Intrinsic - Nothing needs to be added to the blood, coagulation is triggered by factor FXII within the blood coming into contact with a negative surface eg. glass
Extrinsic - Need to add something to the blood in order to activate it to coagulate eg. tissue factor
Which organ is rich in tissue factor and how could you explain that?
Brain - tissue factor triggers the extrinsic coagulation cascade - this is the last place you want internal beeding!
Where is tissue factor located and how does it trigger coagulation?
Located in the endothelium of blood vessels, damage to blood vessels will lead to exposure of TF in the blood, TF is found on the membranes of perivascular cells (smooth muscle cells and fibroblasts)
FVII autoactivates when bound to TF
This plays a role in thrombosis, when a plaque ruptures lots of TF released
What factor are haemophilia A sufferers deficient in?
FVIII
What factor are haemophilia B sufferers deficient in?
FIX
What factors are involved in the consolidation pathway?
Thrombane activates:
FV, FVIII, FXI, FXIII
What co factor is needed to convert prothrombin to thrombin?
Ca2+
What additional substance needs to be present with FXIIIa to form transglutaminase cross links in fibrin clot?
Ca2+
What is hereditary angiodema?
Recurrent episodes of severe oedema in various parts of the body
Types, 1,2 and 3 (type 1 = most common)
Caused by lack of complex blood proteins
What is Leukopenia?
Reduction in the number of WBC’s in the blood
What is thrombocytopenia?
Deficiency in platelets - leads to slow clotting time
What is infectious mononucleosis?
Glandual fever: prolonged lassitude (weariness/lack of energy), viral, swelling of lymph glands
What is disseminated intravascular coagulation?
Widespread activation of the clotting cascade, lots of small clots form, but this consumes platelets and clotting factors, disrupt normal clotting so bleeding can occur
What is factor V leiden?
inherited thrombophilia - increased tendency to form blood clots
What is thrombocythaemia and what can it cause?
High platelet levels, can cause thrombosis
What is hypercoagulability?
Inhibitor deficiencies mean increased risk of thrombosis
HTLV-1 (a retrovirus) has been associated with what cancer?
Leukaemia
Burkitt’s lymphoma is associated with what kind of genetic mutation?
Translocation
How are haematological malignancies classified?
According to blood cell lineage: 1) MYELOID neoplasm or 2) LYMPHOID neoplasm According to location: 1) In the blood = LEUKAEMIA 2) In the lymph nodes = LYMPHOMA Also according to time: ACUTE (blasts) CHRONIC (years - mature cells)
What are myeloproliferative disorders?
Bone marrow makes too many WBC’s or RBC’s or platelets
Slow growing blood cancers which often remain stable or progress quite slowly
What is myelofibrosis?
Increased megakaryocytes - intense bone marrow fibrosis
What is the philadelphia chromosome?
Abnormal small chromosome found in leucocytes of sufferers of leukaemia
What is polycythaemia?
Increased RBC’s - increase in Hb conc, packed cell volume and red cell count
What kind of blood cell is increased in chronic myeloid leukaemia?
Granulocytes
What happens in leukaemia?
1) Accumulation of WBC in the bone marrow and peripheral blood
2) RBC count decreased, platelet count decreased and WBC in the blood increases (abnormal cells though)
3) Leads to bone marrow failure in advanced disease, meaning WBC levels fall
What are the blood symptoms in leukaemia?
1) Blood hyperviscosity due to white cells, causing respiratory or neurological symtoms
2) Infection if white cells fall (bone marrow failure)
3) Tiredness/anaemia
4) Bleeding (platelet count decreased)
5) Bone pain in children
What happens in lymphoma?
T or B lymphocyte neoplasia
Non hodgkin/hodgkin (characterised by reed-steinberg cell - generally originate from B cells which become enlarged and multinucleated or have a bilobed nucleus and have lost the ability to make antibodies
What type of growth factor is involved in the haemapoiesis of myeloid cells including RBCs?
Colony stimulating factors
What type of growth factor is involved in the haemapoiesis of lymphocytes and natural killer cells (the lymphoid line)?
Lymphokines
What is the role of Epo (erythropoietin) in haemapoesis and where is it produced?
Stimulates the formation of bust forming units which form RBCs
Produced by interstitial fibroblasts in the kidneys
Renal failure can lead to anaemia
How is the production of Epo by the kidney controlled?
By negative feedback
high RBCs inhibits the production of Epo by the kidney
What kind of anaemia does iron deficiency lead to and what happens to the RBCs produced?
Microcytic anaemia (pale and small RBCs due to reduced Hb Hypochromic (less Hb in each RBC) Increased anisocytosis (variation in size) and poikilocytosis (variation in shape) - some may be elongated (pencil cells)
Why does VitB12 (or folate) deficiency lead to anaemia?
Vit B12 and folate involved in DNA replication. Deficiency in either causes problems with mitosis of proerythroblast
What kind of anaemia is caused by Vit B12 or folate deficiency?
Megaloblastic or macrocytic anaemia (large RBCs)
Includes the formation of macroovalocytes (enlarged oval shaped RBCs) and also may lead to hypersegmented neutrophils (due to disordered nuclear maturation
What kind of anaemia does blood loss lead to?
Normocytic anaemia (no abnormalities in production)
What are the possible causes of folate deficiency?
1) Poor nutrition
2) Alcoholism
3) Malabsorption
4) Certain drugs (sedatives, certain Abx and anti-epileptics)
Haemolytic syndrome in the new born is an immune cause of aquired haemolytic anaemia, what are the non immune causes?
1) Drug induced
2) Snake venom
3) Mechanical (heart valves)
4) Infections, malaria, septicaemia
What are the 3 problems in inherited haemolytic anaemia?
1) RBC cytoskeleton defects
Mutations in alpha or beta spectrin = hereditary spherocytosis
2) RBC enzyme defects
G6PD deficiency, involved in NADPH metabolism
3) Hb defects
Sickle cells diease
Where are the Hb alpha and beta gene clusters?
Alpha - chromosome 16
Beta - chromosome 11
What are the 3 types of Hb present in adults?
1) HbA (alpha2beta2)
2) HbA2 (alpha2delta2)
3) HbF (alpha2gamma2)
What kind of Hb is found in the foetus?
HbF
What happens in alpha thalassaemia?
Generally large deletions of alpha globin genes
- a/aa and a-/a- = mild
- a/– = severe
- -/– = fatal
What is beta thalassaemia?
Point mutations in the beta-globin gene
If both alleles are affected patient has HbF = beta thalassaemia major
What are the major components in a venous thrombus?
Fibrin
Erythrocytes
What are the 3 points of the triangle on Virchows triangle and what do they define?
1) Circulatory stasis
2) Endothelial injury
3) Hypercoaguability state
Define the 3 factors that contribute to thrombosis
What are the 4 natural inhibitors of coagulation and what do they do?
1) Antithrombin (AT) - direct inhibitor of thrombin, FXa and FIXa
2) Tissue factor pathway inhibitor (TFPI) - direct inhibitor of FVII/TF complex and FXa
3) Activated protein C (aPC)
Proteolytically inactivates FVa and FVIIIa (aPC is a Vit K dependent serine protease, only cuts active forms of the factors
4) Protein S (PS) - cofactor for aPC in the inactivation of FVa/FVIIIa
What is idiopathic venous thrombosis and what is it generally caused by?
Venous thrombosis without any clear cause
Factor V leidens
Deficiency in natural inhibitors of coagulation
What is the mechanism behind Factor V leiden?
Inherited protein C resistance
Substitution mutation in FV gene which increases the risk of DVT
(Cuts FV at 3 arginine bases, one of these arginine bases is replaced by glutamine)
What is fibrinolysis?
Physiological system which helps to break down fibrin when its not needed
Which enzyme breaks down the fibrin clot?
Plasmin
What enzymes are involved in activating plasminogen to plasmin?
tPA and uPA
tPA is secreted by endothelial cells
uPA is important in pregnancy
What substance enhances conversion of plasminogen to plasmin and what does this ensure?
Enhanced by fibrin - this ensures fibrin degradation only occurs at the right place
PAI-1, alpha 2 antiplasmin, TAF1 are all fibrinolytic drugs, what are there targets?
PAI-1 (plasmin activation inhibitor 1) binds to tPA active site
Alpha2antiplasmin - direct inhibitor of plasmin
TAF1 inhibits the enhancement of conversion of plasminogen to plasmin by fibrin
What is the main component of arterial thrombus?
Platelets
What is the process of plaque formation?
1) Plaque forms between tunica media and endothelium
2) Accumulation of foam cells in core (macrophages which have eaten lots of fat)
3) Foam cells produce TF
4) TF, collagen and LPA accumulate in the core
5) Cap of plaque is prone to rupture
6) LPA, and collagen activate platelets
7) TF activates coagulation cascade
How can disseminated intravascular coagulation be caused?
By infection
Sepsis, as a consequence of the infection blood cells expose TF on there membranes
TF activates the coagulation cascade
Microvascular clots
Consumes clotting factors and platelets which leads to bleeding
Get thrombosis and bleeding at the same time
If treatment is ineffective, multiple organ failure occurs
What are the vit K dependent clotting factors?
FVII, FIX and FX, Protein C and Protein S
How are FVII, FIX and FX vitamin K dependent?
1) These clotting factors undergo post translational modification of Glu to gamma-carboxyglutamic acid (Gla) in a Vitamin K dependent reaction
2) Gla binds to activated clotting factors (negatively charged phospholipids) via Ca2+
3) This increases the catalytic efficiency of the limited proteolysis dramatically (so much so it needs this to work)
What enzyme is inhibited by warfarin and what effect does this have?
VKOR, cant regenerate Vit K after it has converted 1 Glu to Gla
What is the cause of Vitamin K deficiency?
Fat malabsorption
May occur in alcoholic liver cirrhosis
May occur in newborn infants
Can occur due to oral anticoagulant over dosage
How are haemophilia A and B inherited?
Sex linked (X-linked recessive)
What stage of thrombin generation is affected in haemophilia A and B?
Consolidation phase
What is the clinical presentation of haemophilia?
Bleeding in knees joints and muscles
What are the 2 different standard coagulation assays and what deficiencies are they prolonged in?
1) PROTHROMBIN TIME (PT)
Uses TF as a trigger
Measures factors in the extrinsic pathway
Prolonged in FVII deficiency
Used in INR monitoring of oral anticoagulants
2) ACTIVATED PARTIAL THROMBOPLASTIN TIME (APTT)
Uses silica as a trigger
Measures factors in intrinsic pathway
Prolonged in FVIII, FIX, FXI and FXII deficiency
-Both are sensitive to deficiencies in the common pathway
What is the possible prophylactic treatment for haemophilia?
Recombinant or plasma factor concentrates
NB. patient may develop an inhibitor against factor concentrates after prolonged treatment
What is Von Willebrand disease and what are the different types?
Deficiency in vWF
1) Type 1: heterozygous disease (autosomal dominant) - commonest and most mild type, reduced level in blood
2) Type 2: functional deficiency (autosomal dominant) - milder than type 3 but more severe than type 1
3) Type 3: complete deficiency (autosomal recessive)
severe
4) Platelet type: mutation in GP1 (receptor for vWF) called pseudo wVF as its clinical presentation is similar to von willebrand disease
Other than its involvement in platelet adhesion and aggregation what else does vWF do?
Stabilises FVIII, without it have less FVIII available
Where is vWF produced?
Produced by endothelial cells and packaged in weibel palade bodies
Also produced by megakaryocytes
Upon stimulation the endothelial cells will secrete it
What does the drug desmopressin do in the treatment of vW disease?
Releases wVF from the weibel palade bodies in endothelial cells
What is thrombasthenia?
dysfunctioning platelets
CAMT (congenital amegakaryocytic thrombocytopenia) and Fanconi’s anaemia causes of?
Fanconi’s anaemia is involved in haematological malignancy and bone marrow failure
Both causes of thrombocytopaenia
Glanzmann thrombasthenia and Bernard-Soulier syndrome are causes of what?
Thrombasthenia
Is the bleeding in thrombocytopenia or thrombasthenia more severe than in haemophilia?
Less severe
What is the treatment for thrombocytopenia/thrombasthenia?
Focuses on the underlying cause
1) Corticosterois in ITP
2) Platelet transfusions
3) Splenectomy (immune suppression)
Immune thrombocytopenic purpura (ITP) is a cause of what?
Thrombocytopenia
